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  <title>JrDong’s Blog</title>
  
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  <link href="http://ibat.xyz/"/>
  <updated>2019-01-18T03:00:00.849Z</updated>
  <id>http://ibat.xyz/</id>
  
  <author>
    <name>JrDong</name>
    
  </author>
  
  <generator uri="http://hexo.io/">Hexo</generator>
  
  <entry>
    <title>重构-在对象之间搬移特性</title>
    <link href="http://ibat.xyz/2019/01/18/%E9%87%8D%E6%9E%84-%E5%9C%A8%E5%AF%B9%E8%B1%A1%E4%B9%8B%E9%97%B4%E6%90%AC%E7%A7%BB%E7%89%B9%E6%80%A7/"/>
    <id>http://ibat.xyz/2019/01/18/重构-在对象之间搬移特性/</id>
    <published>2019-01-18T02:52:15.000Z</published>
    <updated>2019-01-18T03:00:00.849Z</updated>
    
    <content type="html"><![CDATA[<h1 id="重构-在对象之间搬移特性"><a href="#重构-在对象之间搬移特性" class="headerlink" title="重构-在对象之间搬移特性"></a>重构-在对象之间搬移特性</h1><p>《重构：改善既有代码的设计》一书学习笔记。</p>
<h2 id="原则"><a href="#原则" class="headerlink" title="原则"></a>原则</h2><ol>
<li>不要让一个类承担太多责任</li>
<li>迪米特法则：一个对象应该对其他对象保持最少的了解，类与类之间的关系越密切，耦合度越大，当一个类发生改变时，对另一个类的影响也越大。  </li>
<li>能复用的代码尽量抽取，引入外加函数或引入本地扩展</li>
</ol>
<h2 id="方法"><a href="#方法" class="headerlink" title="方法"></a>方法</h2><h3 id="Move-Method（搬移函数）"><a href="#Move-Method（搬移函数）" class="headerlink" title="Move Method（搬移函数）"></a>Move Method（搬移函数）</h3><p>A类中有个函数a,并且含有一个类引用B,如果a函数的逻辑与B相关比较大，则可以考虑将a函数搬移到B中。</p>
<h3 id="Move-Field（搬移字段）"><a href="#Move-Field（搬移字段）" class="headerlink" title="Move Field（搬移字段）"></a>Move Field（搬移字段）</h3><p>对于一个字段，在其所驻类之外的另一个类中有更多的函数使用它，则考虑搬移该字段。或者搬移另一个类的函数，这取决于实际情况。</p>
<h3 id="Extract-Class（提炼类）"><a href="#Extract-Class（提炼类）" class="headerlink" title="Extract Class（提炼类）"></a>Extract Class（提炼类）</h3><p>一个类应该是一个清楚的抽象，处理一些明确的责任。但是在实际开发中，随着业务越来越大，类会不断扩展。当给某个类加一个新的责任时，你会觉得这点责任不足以为它新增一个类，于是随着责任不断增加，这个类就会变得过分复杂。</p>
<h4 id="做法"><a href="#做法" class="headerlink" title="做法"></a>做法</h4><ul>
<li>决定如果分解类的责任</li>
<li>建立一个新类，用以承载旧类的某些责任。</li>
<li>建立从旧类访问新类的连接关系，有可能是双向连接，但是尽量不要建立新类到旧类的连接。</li>
</ul>
<h4 id="范例"><a href="#范例" class="headerlink" title="范例"></a>范例</h4><pre><code>class Person...
   public String getName() {
       return _name;
   }
   public String getTelephoneNumber() {
       return (&quot;(&quot; + _officeAreaCode + &quot;) &quot; + _officeNumber);
   }
   String getOfficeAreaCode() {
       return _officeAreaCode;
   }
   void setOfficeAreaCode(String arg) {
       _officeAreaCode = arg;
   }
   String getOfficeNumber() {
       return _officeNumber;
   }
   void setOfficeNumber(String arg) {
       _officeNumber = arg;
   }
   private String _name;
   private String _officeAreaCode;
   private String _officeNumber;
</code></pre><p>可以将电话号码相关的内容抽取出来，变为TelephoneNumber类 如下：</p>
<pre><code>class Person...
    private String _name;
   private TelephoneNumber _officeTelephone = new TelephoneNumber();
   public String getName() {
       return _name;
   }
   public String getTelephoneNumber(){
       return _officeTelephone.getTelephoneNumber();
   }
   TelephoneNumber getOfficeTelephone() {
       return _officeTelephone;
   }

class TelephoneNumber...
   private String _number;
   private String _areaCode;
   public String getTelephoneNumber() {
       return (&quot;(&quot; + _areaCode + &quot;) &quot; + _number);
   }
   String getAreaCode() {
       return _areaCode;
   }
   void setAreaCode(String arg) {
       _areaCode = arg;
   }
   String getNumber() {
       return _number;
   }
   void setNumber(String arg) {
       _number = arg;
   }
</code></pre><p>这样做后TelephoneNumber便成了Person的一个属性，但是还需要思考一个问题，要不要把TelephoneNumber暴露出去，如果暴露出去，那么其他类直接改TelephoneNumber的内容,Pserson是不知情的，这就会带来一些问题。所以非必要情况下，可以只暴露某些方法，或者只暴露给部分用户，也就是protect或者default作用域下的</p>
<h3 id="Inline-Class（将类内联化）"><a href="#Inline-Class（将类内联化）" class="headerlink" title="Inline Class（将类内联化）"></a>Inline Class（将类内联化）</h3><p>你的某个class没有做太多事情（没有承担足够责任）。<br>将class的所有特性搬移到另一个class中，然后移除原class。<br>与提炼类正好相反，如果一个class不再承担足够 责任、不再有单独存在的理由〔这通常是因为此前的重构动作移走了这个class的 责任），这时候找出与这个class关联最频繁的class，将两个class合并成一个。与上述相同，不做赘述了。  </p>
<h3 id="Hide-Delegate（隐藏「委托关系」）"><a href="#Hide-Delegate（隐藏「委托关系」）" class="headerlink" title="Hide Delegate（隐藏「委托关系」）"></a>Hide Delegate（隐藏「委托关系」）</h3><p>「封装」意味每个对象都应该尽可能少了解系统的其他部分。如此一来，一旦发生变化，需要了解这一 变化的对象就会比较少——这会使变化比较容易进行。<br>这个原则有点像迪米特法则，即一个对象应该对其他对象保持最少的了解。<br>我们从一个例子来理解</p>
<pre><code>class Person {
  Department _department;
  public Department getDepartment() {
      return _department;
  }
  public void setDepartment(Department arg) {
      _department = arg;
  }
}
class Department {
  private String _chargeCode;
  private Person _manager;
  public Department (Person manager) {
      _manager = manager;
  }
  public Person getManager() {
      return _manager;
  }
...
</code></pre><p>如果客户希望知道某人的经理是谁，他必须先取得Department对象：  </p>
<pre><code>manager = john.getDepartment().getManager();
</code></pre><p>这样的编码就是对客户揭露了Department的工作原理，于是客户知道：Department用以追踪「经理」这条信息。如果对客户隐藏Department，可以减少耦合（coupling）。 为了这一目的，我在Person中建立一个简单的委托函数：  </p>
<pre><code>public Person getManager() {
  return _department.getManager();
   }
</code></pre><p>现在，我得修改Person的所有客户，让它们改用新函数：</p>
<pre><code>manager = john.getManager();
</code></pre><p>只要完成了对Department所有函数的委托关系，并相应修改了Person的所有客 户，我就可以移除Person中的访问函数getDepartment()了。</p>
<h3 id="Remove-Middle-Man（移除中间人）"><a href="#Remove-Middle-Man（移除中间人）" class="headerlink" title="Remove Middle Man（移除中间人）"></a>Remove Middle Man（移除中间人）</h3><p>某个class做了过多的简单委托动作（simple delegation）。<br>让客户直接调用delegate（受托类）。<br>这个与上面的隐藏委托关系正好相反。这个很好理解，如果一个类委托了另一个类的所有方法，那么就没必要设置委托了。  </p>
<h3 id="Introduce-Foreign-Method（引入外加函数）"><a href="#Introduce-Foreign-Method（引入外加函数）" class="headerlink" title="Introduce Foreign Method（引入外加函数）"></a>Introduce Foreign Method（引入外加函数）</h3><p>你正在使用一个class，它真的很好，为你提供了你想要的所有服务。而后，你又需要一项新服务，这个class却无法供应。于是你开始咒骂：「为什么不能做这件事？」如果可以修改源码，你便可以自行添加一个新函数； 如果不能，你就得在客户端编码，补足你要的那个函数。<br>如果client class只使用这项功能一次，那么额外编码工作没什么大不了，甚至可能根本不需要原本提供服务的那个class。然而如果你需要多次使用这个函数，你就得不断重复这些代码，这些重复性代码应该被抽出来放进同一个函数中。如果你发现自己为一个server class建立了大量外加函数，或如果你发现有许多classes都需要同样的外加函数，你就不应该再使用本项重构，而应该使用 Introduce Local Extension。  </p>
<pre><code>Date newStart = new Date (previousEnd.getYear(),previousEnd.getMonth(), previousEnd.getDate() + 1);
</code></pre><p>为了避免每次像上面这样写，可以引入外加函数  </p>
<pre><code>  Date newStart = nextDay(previousEnd);
private static Date nextDay(Date arg) {
    return new Date (arg.getYear(),arg.getMonth(), arg.getDate() + 1);
} 
</code></pre><h3 id="Introduce-Local-Extension（引入本地扩展）"><a href="#Introduce-Local-Extension（引入本地扩展）" class="headerlink" title="Introduce Local Extension（引入本地扩展）"></a>Introduce Local Extension（引入本地扩展）</h3><p>同样的，当一个类中，没有你需要的函数时,但是这个函数需要被大量的classes使用，这时候就需要使用本方法。如果这个类可以修改其源码，那么可以直接在源码中修改，但是大部分情况应该是不可以修改的。这时候就可以建立一个新class，使它包含这些额外函数。可以成为source class的subclass （子类〕或wrapper（外覆类）  </p>
<h4 id="使用subclass"><a href="#使用subclass" class="headerlink" title="使用subclass"></a>使用subclass</h4><p>首先，我要建立一个新的DateSub class来表示「日期」，并使其成为Date的subclass：  </p>
<pre><code>class DateSub extends Date{
    Date nextDay() {
        return new Date (getYear(),getMonth(), getDate() + 1);
      }
  }
</code></pre><p>当需要获得nextDay时，就可调用DateSub中的nextDay();</p>
<h4 id="使用wrapper"><a href="#使用wrapper" class="headerlink" title="使用wrapper"></a>使用wrapper</h4><p>声明一个wrapping class：  </p>
<pre><code>class DateWrapper {
   private Date _original;
   public DateWrapper (String dateString) {
      _original = new Date(dateString);
      };
 }
</code></pre>]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;重构-在对象之间搬移特性&quot;&gt;&lt;a href=&quot;#重构-在对象之间搬移特性&quot; class=&quot;headerlink&quot; title=&quot;重构-在对象之间搬移特性&quot;&gt;&lt;/a&gt;重构-在对象之间搬移特性&lt;/h1&gt;&lt;p&gt;《重构：改善既有代码的设计》一书学习笔记。&lt;/p&gt;
&lt;h2 
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
  </entry>
  
  <entry>
    <title>重构-重新组织函数</title>
    <link href="http://ibat.xyz/2019/01/17/%E9%87%8D%E6%9E%84-%E9%87%8D%E6%96%B0%E7%BB%84%E7%BB%87%E5%87%BD%E6%95%B0/"/>
    <id>http://ibat.xyz/2019/01/17/重构-重新组织函数/</id>
    <published>2019-01-17T02:52:15.000Z</published>
    <updated>2019-01-17T02:58:55.788Z</updated>
    
    <content type="html"><![CDATA[<h1 id="重新组织函数"><a href="#重新组织函数" class="headerlink" title="重新组织函数"></a>重新组织函数</h1><p>《重构：改善既有代码的设计》一书学习笔记。<br>并没有完全写出书中所有例子，只摘抄了自己认为比较常用的一些，如果感兴趣可以阅读书籍.</p>
<h2 id="原则"><a href="#原则" class="headerlink" title="原则"></a>原则</h2><ol>
<li>代码的命名和函数应该让程序员看到后就像注释一样，可以不看这段代码的逻辑就知道这段代码是做什么的。</li>
<li>一个函数只做一件事情，如果函数超过一定行数，比如说一屏，那么这段代码一定做了不止一件事情，可以将函数进行拆分。</li>
</ol>
<h2 id="方法"><a href="#方法" class="headerlink" title="方法"></a>方法</h2><h3 id="提取临时变量"><a href="#提取临时变量" class="headerlink" title="提取临时变量"></a>提取临时变量</h3><p>例如:</p>
<pre><code>private double getPrice(){
    int basePrice = quantity * itemPrice;
    double discontFactor;
    if (basePrice &gt; 1000){
        discontFactor = 0.85;
    } else{
        discontFactor = 0.95;
    }
    return basePrice * discontFactor;
}
</code></pre><p>step1<br>basePrice是一个通用的计算方式，数量*单价，所以为了保证其他函数也可以调用，我们把临时变量basePrice抽取成basePrice()，结果如下:</p>
<pre><code>private double getPrice(){
    double discontFactor;
    if (basePrice() &gt; 1000){
        discontFactor = 0.85;
    } else{
        discontFactor = 0.95;
    }
    return basePrice() * discontFactor;
}

private int basePrice(){
    return quantity * itemPrice;
}
</code></pre><p>step2<br>变量discontFactor，也可以用类似方法提取  </p>
<pre><code>private double getPrice(){
    return basePrice() * discontFactor();
}

private int basePrice(){
    return quantity * itemPrice;
}

private double getDiscontFactor(){
    if (basePrice() &gt; 1000){
        return 0.85;
    } else{
        return 0.95;
    }

}
</code></pre><p>ok,经过上面的提取，我们直接看getPrice方法，可以一眼明确，价格 = 总价 * 折扣,甚至我们根本不用关心总价和折扣是怎么来的，总之我要的只是一个价格.</p>
<h3 id="加入解释性变量"><a href="#加入解释性变量" class="headerlink" title="加入解释性变量"></a>加入解释性变量</h3><p>例如，我们经常可以看到，if判断语句中做了复杂的判断，一般令人难以理解，这时候应该将复杂的判断用一个解释行的变量来代替</p>
<pre><code>if((platform.toUpperCase().indexOf(&quot;MAC&quot;)))
        ||(platform.toUpperCase().indexOf(&quot;WINDOWS&quot;)){

}
</code></pre><p>乍一看很长一段判断，不容易让人一眼看明白，我们就可以加入解释性变量解决</p>
<pre><code>boolean isMacOs = platform.toUpperCase().indexOf(&quot;MAC&quot;) &gt; -1;
boolean isWindowsOs = platform.toUpperCase().indexOf(&quot;WINDOWS&quot;);
if(isMacOs || isWindowsOs){

}
</code></pre><p>这样同样的我们不用关心是怎么判断是mac还是windows的，if语句变得清晰明了.</p>
<h3 id="移除对参数的赋值"><a href="#移除对参数的赋值" class="headerlink" title="移除对参数的赋值"></a>移除对参数的赋值</h3><p>如果不必要，不要直接对函数的参数赋值，但有些时候是需要的，个人感觉不是很强制.<br>例1,容易让人误会的赋值,赋值对基本数据类型无效,所以新命名一个变量比较好理解:  </p>
<pre><code>public static void main(String[] args){
    int x = 5;
    triple(x);
    print(&quot;x = &quot; + x);
}

private static void triple(int x){
    x = x * 3;
    print(&quot;x = &quot; + x);
}
</code></pre><p>例2，对对象赋值</p>
<pre><code>public static void main(String[] args){
    Date d1 = new Date(&quot;1 Apr 98&quot;);
    nextDateUpdate(d1);
    print(&quot;d1 after nextDay&quot; + d1);

    Date d2 = new Date(&quot;1 Apr 98&quot;);
    nextDateReplace(d2);
    print(&quot;d2 after nextDay&quot; + d2);
}

private static void nextDateUpdate(Date date){
    date.setDate(date.getDate() + 1);
    print(&quot;date in nextDay&quot; + date);
}

private static void nextDateReplace(Date date){
    date = new Date(date.getYear(), date.getMonth(), date.getDate() + 1);
    print(&quot;date in nextDay&quot; + date);
}
</code></pre><h3 id="替换算法"><a href="#替换算法" class="headerlink" title="替换算法"></a>替换算法</h3><p>替换更清晰的算法,例如:</p>
<pre><code>private String foundPerson(String[] people){
    for (int i = 0 ; i &lt; people.length ; i++){
        if(&quot;Don&quot;.equals(people[i])){
            return &quot;Don&quot;;
        }
        if(&quot;John&quot;.equals(people[i])){
            return &quot;John&quot;;
        }
        if(&quot;Kent&quot;.equals(people[i])){
            return &quot;Kent&quot;;
        }
    }
    return &quot;&quot;;
}
</code></pre><p>看起来似乎也比较清晰，但是试想一下，person变成了10个，甚至更多怎么办，是不是要写10个if判断。所以我们采用另一种方式</p>
<pre><code>private String foundPerson(String[] people){
    List candidates = Arrays.asList(new String[]{&quot;Don&quot;, &quot;John&quot;,&quot;Kent&quot;});
    for (int i = 0 ; i &lt; people.length ; i++){
        if(condidates.contains(people[i])){
            return people[i];
        }    
    }
    return &quot;&quot;;
}
</code></pre><p>这样如果加更多的人名，只需要往条件中添加就可以.</p>
]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;重新组织函数&quot;&gt;&lt;a href=&quot;#重新组织函数&quot; class=&quot;headerlink&quot; title=&quot;重新组织函数&quot;&gt;&lt;/a&gt;重新组织函数&lt;/h1&gt;&lt;p&gt;《重构：改善既有代码的设计》一书学习笔记。&lt;br&gt;并没有完全写出书中所有例子，只摘抄了自己认为比较常用的一些
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
  </entry>
  
  <entry>
    <title>Android setContentView与findViewById源码解析</title>
    <link href="http://ibat.xyz/2017/07/24/Android-setContentView%E4%B8%8EfindViewById%E6%BA%90%E7%A0%81%E8%A7%A3%E6%9E%90/"/>
    <id>http://ibat.xyz/2017/07/24/Android-setContentView与findViewById源码解析/</id>
    <published>2017-07-24T07:29:28.000Z</published>
    <updated>2017-07-24T12:48:19.000Z</updated>
    
    <content type="html"><![CDATA[<p>当我们给Activity设置布局时，都是直接调用setContentView来完成的，但具体Android是怎么把布局加载到window，又是怎么通过findViewById获取view对象的，我们可能并没有太关心，下面就结合源码来分析下这个过程。</p>
<h1 id="Android-setContentView"><a href="#Android-setContentView" class="headerlink" title="Android setContentView"></a>Android setContentView</h1><p>打开Activity的源码发现，setContentView有三个重载方法，  </p>
<ol>
<li>public void setContentView(int layoutResID);  </li>
<li>public void setContentView(View view);  </li>
<li>public void setContentView(View view, ViewGroup.LayoutParams params)<br>我们就来看下最常用的第一个方法:  </li>
</ol>
<pre><code class="java"><span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">setContentView</span><span class="params">(<span class="keyword">int</span> layoutResID)</span> </span>{
    getWindow().setContentView(layoutResID);
    initWindowDecorActionBar();
}
</code></pre>
<p>这个方法调用了,Window类中的setContentView()方法，其他方法也是调用了Window类中的setContentView()，但是Window是一个抽象类，在Activity的attach方法中被初始化，其实是一个PhoneWindow实例，所以这个setContentView方法在PhoneWindow中实现。      </p>
<pre><code class="java"><span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">setContentView</span><span class="params">(<span class="keyword">int</span> layoutResID)</span> </span>{
    <span class="comment">// Note: FEATURE_CONTENT_TRANSITIONS may be set in the process of installing the window</span>
    <span class="comment">// decor, when theme attributes and the like are crystalized. Do not check the feature</span>
    <span class="comment">// before this happens.</span>
    <span class="keyword">if</span> (mContentParent == <span class="keyword">null</span>) {
        installDecor();
    } <span class="keyword">else</span> <span class="keyword">if</span> (!hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
        mContentParent.removeAllViews();
    }

    <span class="keyword">if</span> (hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
        <span class="keyword">final</span> Scene newScene = Scene.getSceneForLayout(mContentParent, layoutResID,
                getContext());
        transitionTo(newScene);
    } <span class="keyword">else</span> {
        mLayoutInflater.inflate(layoutResID, mContentParent);
    }
    <span class="keyword">final</span> Callback cb = getCallback();
    <span class="keyword">if</span> (cb != <span class="keyword">null</span> &amp;&amp; !isDestroyed()) {
        cb.onContentChanged();
    }
}
</code></pre>
<p>首先判断mContentParent是否为空，如果为空的话则调用installDecor()方法，其次判断是否设置了FEATURE_CONTENT_TRANSITIONS属性，如果没有的话则移除所有view（从这里我们可以得出setContentView可以调用多次，反正会removeAllViews），然后调用LayoutInflater.inflate(),将我们设置的布局文件添加到mContentParent中。接着获取了一个Callback对象，那这个是在Activity的attach方法中设置的一个回调  </p>
<pre><code class="java">mWindow.setCallback(<span class="keyword">this</span>);
</code></pre>
<p>所以可以得出在Activity中一定有一个onContentChanged回调，我们来看下这个回调  </p>
<pre><code class="java"><span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">onContentChanged</span><span class="params">()</span> </span>{}
</code></pre>
<p> 额，空空如也。但是我们可以在自己的Activity中重写这个回调，用于在setContentView之后做一些事情，比如findViewById,但貌似实际场景也不需要。。。<br> 好了，现在我们回到上面提到的installDecor()方法，好长，我们捡重要的看吧。  </p>
<pre><code class="java"><span class="function"><span class="keyword">private</span> <span class="keyword">void</span> <span class="title">installDecor</span><span class="params">()</span> </span>{
              <span class="comment">//初始化decorView</span>
            <span class="keyword">if</span> (mDecor == <span class="keyword">null</span>) {
                mDecor = generateDecor();
                mDecor.setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
                mDecor.setIsRootNamespace(<span class="keyword">true</span>);
                <span class="keyword">if</span> (!mInvalidatePanelMenuPosted &amp;&amp; mInvalidatePanelMenuFeatures != <span class="number">0</span>) {
                    mDecor.postOnAnimation(mInvalidatePanelMenuRunnable);
                }
            }
            <span class="comment">//初始化mContentParent</span>
            <span class="keyword">if</span> (mContentParent == <span class="keyword">null</span>) {
                mContentParent = generateLayout(mDecor);
                  ......
                  <span class="comment">//设置一堆属性值</span>
            }
    }
</code></pre>
<p>看下PhoneWindow中的generateDecor()方法    </p>
<pre><code class="java"><span class="function"><span class="keyword">protected</span> DecorView <span class="title">generateDecor</span><span class="params">()</span> </span>{
          <span class="keyword">return</span> <span class="keyword">new</span> DecorView(getContext(), -<span class="number">1</span>);
    }
</code></pre>
<p>只是单纯的new了一个DecorView实例。这个DecorView是什么鬼。其实它是PhoneWindow的一个内部类，是整个window界面最顶层的view。包含ActionBar,内容块等。好了，现在我们缕一下Window,PhoneWindow，decorView的关系  </p>
<p>1.Window类是一个抽象类，提供了绘制窗口的一组通用API。可以将之理解为一个载体，各种View在这个载体上显示。<br>2.PhoneWindow是Window的一个子类，是Window的具体实现，包含一个内部类DecorView,PhoneWindow是将decorView进行了一定包装，并提供一些方法用于操作窗口。<br>3。DecorView继承自FrameLayout,是窗口的根view。  </p>
<p>好了，接着看mContentParent的初始化，generateLayout(mDecor).这里传入了上一部初始化好的DecorView. 又是一个长方法，我们还是挑出重要的部分。   </p>
<pre><code class="java"><span class="function"><span class="keyword">protected</span> ViewGroup <span class="title">generateLayout</span><span class="params">(DecorView decor)</span> </span>{
        <span class="comment">// Apply data from current theme.</span>

        TypedArray a = getWindowStyle();

        <span class="comment">//......</span>
        <span class="comment">//根据定义的style设置一些值，比如是否显示ActionBar,</span>

        <span class="comment">// Inflate the window decor.</span>

        <span class="keyword">int</span> layoutResource;
        <span class="keyword">int</span> features = getLocalFeatures();
        <span class="comment">//......</span>
        <span class="comment">//根据设定好的features值选择不同的窗口修饰布局文件,</span>
        <span class="comment">//得到layoutResource值，系统定义了不同的layout，比如  </span>
        <span class="comment">//R.layout.screen_custom_title,R.layout.screen_simple</span>

        <span class="comment">//把选中的窗口修饰布局文件添加到DecorView对象里，并且指定contentParent值</span>
        View in = mLayoutInflater.inflate(layoutResource, <span class="keyword">null</span>);
        decor.addView(in, <span class="keyword">new</span> ViewGroup.LayoutParams(MATCH_PARENT, MATCH_PARENT));
        mContentRoot = (ViewGroup) in;

        ViewGroup contentParent = (ViewGroup)findViewById(ID_ANDROID_CONTENT);
        <span class="keyword">if</span> (contentParent == <span class="keyword">null</span>) {
            <span class="keyword">throw</span> <span class="keyword">new</span> RuntimeException(<span class="string">"Window couldn't find content container view"</span>);
        }

        <span class="comment">//......</span>
        <span class="comment">//继续一堆属性设置,返回contentParent</span>
        <span class="keyword">return</span> contentParent;
    }
</code></pre>
<p>根据不同的features值，设定layoutResource，最终添加到decorView中，所以我们通过在xml中设置的theme，还有在代码中设置的requestWindowFeature,都是用来设置features值，这也是为什么requestWindowFeature方法必须在setContentView之前的原因。<br>这样看来，如果我们设置我们的Theme为NoTitleBar,最终layoutResource的值为R.layout.screen_simple   </p>
<pre><code class="xml"><span class="tag">&lt;<span class="name">LinearLayout</span> <span class="attr">xmlns:android</span>=<span class="string">"http://schemas.android.com/apk/res/android"</span>
    <span class="attr">android:layout_width</span>=<span class="string">"match_parent"</span>
    <span class="attr">android:layout_height</span>=<span class="string">"match_parent"</span>
    <span class="attr">android:fitsSystemWindows</span>=<span class="string">"true"</span>
    <span class="attr">android:orientation</span>=<span class="string">"vertical"</span>&gt;</span>
    <span class="tag">&lt;<span class="name">ViewStub</span> <span class="attr">android:id</span>=<span class="string">"@+id/action_mode_bar_stub"</span>
              <span class="attr">android:inflatedId</span>=<span class="string">"@+id/action_mode_bar"</span>
              <span class="attr">android:layout</span>=<span class="string">"@layout/action_mode_bar"</span>
              <span class="attr">android:layout_width</span>=<span class="string">"match_parent"</span>
              <span class="attr">android:layout_height</span>=<span class="string">"wrap_content"</span>
              <span class="attr">android:theme</span>=<span class="string">"?attr/actionBarTheme"</span> /&gt;</span>
    <span class="tag">&lt;<span class="name">FrameLayout</span>
         <span class="attr">android:id</span>=<span class="string">"@android:id/content"</span>
         <span class="attr">android:layout_width</span>=<span class="string">"match_parent"</span>
         <span class="attr">android:layout_height</span>=<span class="string">"match_parent"</span>
         <span class="attr">android:foregroundInsidePadding</span>=<span class="string">"false"</span>
         <span class="attr">android:foregroundGravity</span>=<span class="string">"fill_horizontal|top"</span>
         <span class="attr">android:foreground</span>=<span class="string">"?android:attr/windowContentOverlay"</span> /&gt;</span>
<span class="tag">&lt;/<span class="name">LinearLayout</span>&gt;</span>
</code></pre>
<p>来看下去处标题栏后的视图树  </p>
<p><img src="/img/setContentView1.png" alt="setContentView"> </p>
<p>所以installDecor主要是初始化了PhoneWindow中的DecorView.和contentParent,之后在setContentView()中通过mLayoutInflater.inflate(layoutResID, mContentParent);将layoutResId,add到初始化好的contentParent中。<br>大家是否好奇状态栏怎么被加载进DecorView的，我们来看下DecorView中的updateColorViewInt方法  </p>
<pre><code class="java"><span class="function"><span class="keyword">private</span> View <span class="title">updateColorViewInt</span><span class="params">(View view, <span class="keyword">int</span> sysUiVis, <span class="keyword">int</span> systemUiHideFlag,
            <span class="keyword">int</span> translucentFlag, <span class="keyword">int</span> color, <span class="keyword">int</span> height, <span class="keyword">int</span> verticalGravity,
            String transitionName, <span class="keyword">int</span> id, <span class="keyword">boolean</span> hiddenByWindowFlag)</span> </span>{
          ......
        <span class="keyword">if</span> (view == <span class="keyword">null</span>) {
            <span class="keyword">if</span> (show) {
                view = <span class="keyword">new</span> View(mContext);
                view.setBackgroundColor(color);
                view.setTransitionName(transitionName);
                view.setId(id);
                addView(view, <span class="keyword">new</span> LayoutParams(LayoutParams.MATCH_PARENT, height,
                        Gravity.START | verticalGravity));
            }
        } <span class="keyword">else</span> {
           ......
               }
        <span class="keyword">return</span> view;
    }
</code></pre>
<p>可以看到直接new了一个view，这个view就是状态栏，然后将状态栏添加到了DecorView,其实这个状态栏只是一个单纯的占位view。被updateColorViews方法调用，比如当我们调用setStatusBarColor时就是调用了updateColorViews这个方法。这里先不做过多介绍。</p>
<h1 id="findViewById"><a href="#findViewById" class="headerlink" title="findViewById"></a>findViewById</h1><p>那么将layout添加进decorView中后，我们是怎么通过findViewById找到View的呢？<br>看下Activity的findViewById方法  </p>
<pre><code class="java"><span class="comment">/**
 * Finds a view that was identified by the id attribute from the XML that
 * was processed in {<span class="doctag">@link</span> #onCreate}.
 *
 * <span class="doctag">@return</span> The view if found or null otherwise.
 */</span>
<span class="function"><span class="keyword">public</span> View <span class="title">findViewById</span><span class="params">(<span class="keyword">int</span> id)</span> </span>{
    <span class="keyword">return</span> getWindow().findViewById(id);
}
</code></pre>
<p>又是到了window中，看下window中的方法  </p>
<pre><code class="java"><span class="function"><span class="keyword">public</span> View <span class="title">findViewById</span><span class="params">(<span class="keyword">int</span> id)</span> </span>{
    <span class="keyword">return</span> getDecorView().findViewById(id);
}
</code></pre>
<p>是调用了getDecorView的findViewById，也就是调用了view的findViewById,我们来看下view类中  </p>
<pre><code class="java"><span class="function"><span class="keyword">public</span> <span class="keyword">final</span> View <span class="title">findViewById</span><span class="params">(<span class="keyword">int</span> id)</span> </span>{
    <span class="keyword">if</span> (id &lt; <span class="number">0</span>) {
        <span class="keyword">return</span> <span class="keyword">null</span>;
    }
    <span class="keyword">return</span> findViewTraversal(id);
}

<span class="function"><span class="keyword">protected</span> View <span class="title">findViewTraversal</span><span class="params">(<span class="keyword">int</span> id)</span> </span>{
    <span class="keyword">if</span> (id == mID) {
        <span class="keyword">return</span> <span class="keyword">this</span>;
    }
    <span class="keyword">return</span> <span class="keyword">null</span>;
}
</code></pre>
<p>到这我们就疑惑了，直接判断了id是否为view的id，是的话就返回。怎么也应该有一个循环或者递归查找啊，什么都没有。<br>这时我们来看下，mID是怎么初始化的    </p>
<pre><code class="java"> ....
 <span class="keyword">case</span> com.android.internal.R.styleable.View_id:
                 mID = a.getResourceId(attr, NO_ID);
                 <span class="keyword">break</span>;
...
</code></pre>
<p>喔，这个id就是我们在xml中设置的id。那会不会在ViewGroup中进行查找的呢？来看下  </p>
<pre><code class="java"><span class="function"><span class="keyword">protected</span> View <span class="title">findViewTraversal</span><span class="params">(<span class="keyword">int</span> id)</span> </span>{
    <span class="keyword">if</span> (id == mID) {
        <span class="keyword">return</span> <span class="keyword">this</span>;
    }

    <span class="keyword">final</span> View[] where = mChildren;
    <span class="keyword">final</span> <span class="keyword">int</span> len = mChildrenCount;

    <span class="keyword">for</span> (<span class="keyword">int</span> i = <span class="number">0</span>; i &lt; len; i++) {
        View v = where[i];

        <span class="keyword">if</span> ((v.mPrivateFlags &amp; PFLAG_IS_ROOT_NAMESPACE) == <span class="number">0</span>) {
            v = v.findViewById(id);

            <span class="keyword">if</span> (v != <span class="keyword">null</span>) {
                <span class="keyword">return</span> v;
            }
        }
    }

    <span class="keyword">return</span> <span class="keyword">null</span>;
}
</code></pre>
<p>果然， ViewGroup重写了View的findViewTraversal()方法，遍历了自己的child的findViewById方法，如果找到了返回View自身。<br>ok,到现在我们就理解了view是怎么findViewById的了。   </p>
<h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><p>上面我们介绍了，Activity setContentView和findViewById的流程，是不是又多了一层理解呢，接下来我们会介绍，LayoutInflater是怎么把资源文件inflate到view中的，还有view的加载机制。如果有漏掉的之后再进行补充</p>
]]></content>
    
    <summary type="html">
    
      &lt;p&gt;当我们给Activity设置布局时，都是直接调用setContentView来完成的，但具体Android是怎么把布局加载到window，又是怎么通过findViewById获取view对象的，我们可能并没有太关心，下面就结合源码来分析下这个过程。&lt;/p&gt;
&lt;h1 id=&quot;
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
      <category term="Android" scheme="http://ibat.xyz/tags/Android/"/>
    
      <category term="资源加载" scheme="http://ibat.xyz/tags/%E8%B5%84%E6%BA%90%E5%8A%A0%E8%BD%BD/"/>
    
  </entry>
  
  <entry>
    <title>Drawable mutations解析</title>
    <link href="http://ibat.xyz/2017/06/14/Drawable%20mutations%E8%A7%A3%E6%9E%90/"/>
    <id>http://ibat.xyz/2017/06/14/Drawable mutations解析/</id>
    <published>2017-06-14T15:19:06.000Z</published>
    <updated>2017-07-24T06:04:23.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="Drawable-mutations"><a href="#Drawable-mutations" class="headerlink" title="Drawable mutations"></a>Drawable mutations</h1><p>有没有遇到过这样一种情况，我们要加载同一资源到两个ImageView，但需要给其中一个资源改变颜色或者透明度。如下面的代码  </p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div></pre></td><td class="code"><pre><div class="line">ImageView imageView1 = (ImageView) view.findViewById(R.id.imageview);</div><div class="line">   ImageView imageView2 = (ImageView) view.findViewById(R.id.imageview2);</div><div class="line"></div><div class="line">   Drawable drawable = getResources().getDrawable(R.mipmap.ic_launcher);</div><div class="line">   drawable.setColorFilter(Color.RED, PorterDuff.Mode.SRC_ATOP);</div><div class="line">imageView.setImageDrawable(drawable);</div><div class="line"></div><div class="line">Drawable drawable1 = getResources().getDrawable(R.mipmap.ic_launcher);</div><div class="line">imageView2.setImageDrawable(drawable1);</div></pre></td></tr></table></figure>
<p>我们给imageView1设置ColorFilter改变一下图标的颜色，imageview2保持不变。这样会发生什么呢，看下面的图:  </p>
<p><img src="/img/drawable_mutate1.png" alt="mutate(1)">  </p>
<p>这时候奇怪的事情发生了，两个ImageView都被改变了颜色。这是因为Drawable使用在Android系统中使用范围比较广，系统对此作了优化，同一资源的drawable共享一个状态，叫做ConstantState.例如,上面的R.mipmap.ic_launcher,每次新建一个drawable都是一个不同的drawable实例,但他们共享一个状态,这个状态中包含bitmap image,所以所有的R.mipmap.ic_launcher都共享一个bitmap,这就是两个ImageView都改变颜色原因。 </p>
<blockquote>
<p>Because drawables are used so extensively throughout the system, Android optimizes them when they are loaded from resources. For instance, every time you create a Button, a new drawable is loaded from the framework resources (android.R.drawable.btn_default). This means all buttons across all the apps use a different drawable instance as their background. However, all these drawables share a common state, called the “constant state.” The content of this state varies according to the type of drawable you are using, but it usually contains all the properties that can be defined by a resource. In the case of a button, the constant state contains a bitmap image. This way, all buttons across all applications share the same bitmap, which saves a lot of memory.(摘抄自<a href="https://android-developers.googleblog.com/2009/05/drawable-mutations.html" target="_blank" rel="external">Android Developers Blog</a>)。如下图所示    </p>
</blockquote>
<p><img src="/img/drawable_mutate2.png" alt="mutate(2)"></p>
<p>但有没有办法解决呢，Drawable提供了一个mutate方法，我们来看下mutate方法的注释  </p>
<blockquote>
<p>Make this drawable mutable. This operation cannot be reversed. A mutable drawable is guaranteed to not share its state with any other drawable. This is especially useful when you need to modify properties of drawables loaded from resources. By default, all drawables instances loaded from the same resource share a common state; if you modify the state of one instance, all the other instances will receive the same modification. Calling this method on a mutable Drawable will have no effect.</p>
</blockquote>
<p>mutate不知道怎么翻译合适，姑且叫做可变的吧。这个mutate方法使得这个drawable变成可变的，这个操作不可逆转。调用了mutate方法，使得该drawable不和其他drawable共享状态。<br>我们来看下这个mutate的实现，发现在Drawable源码中，mutate方法只是返回了他自身。那我们来看下drawable子类有没有对该方法重写。我们找到BitmapDrawable  </p>
<pre><code class="java"> <span class="meta">@Override</span>
<span class="function"><span class="keyword">public</span> Drawable <span class="title">mutate</span><span class="params">()</span> </span>{
    <span class="keyword">if</span> (!mMutated &amp;&amp; <span class="keyword">super</span>.mutate() == <span class="keyword">this</span>) {
        mBitmapState = <span class="keyword">new</span> BitmapState(mBitmapState);
        mMutated = <span class="keyword">true</span>;
    }
    <span class="keyword">return</span> <span class="keyword">this</span>;
}
</code></pre>
<p>如果没有调用过mutate方法，会新建一个BitmapState，再将mMutated置为true。这样相当于做了一次状态的拷贝，就不会与其他drawable共享状态了。<br>接下来我们修改下上面的代码  </p>
<pre><code class="java">ImageView imageView1 = (ImageView) view.findViewById(R.id.imageview);
ImageView imageView2 = (ImageView) view.findViewById(R.id.imageview2);

Drawable drawable = getResources().getDrawable(R.mipmap.ic_launcher).mutate();
drawable.setColorFilter(Color.RED, PorterDuff.Mode.SRC_ATOP);
imageView.setImageDrawable(drawable);

Drawable drawable1 = getResources().getDrawable(R.mipmap.ic_launcher);
imageView2.setImageDrawable(drawable1);
</code></pre>
<p>运行效果:  </p>
<p><img src="/img/drawable_mutate3.png" alt="mutate3"><br>这次两个ImageView不相同了，下一节我们来学习下资源的加载机制，看Resources类是怎么加载资源的。</p>
]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;Drawable-mutations&quot;&gt;&lt;a href=&quot;#Drawable-mutations&quot; class=&quot;headerlink&quot; title=&quot;Drawable mutations&quot;&gt;&lt;/a&gt;Drawable mutations&lt;/h1&gt;&lt;p&gt;有没有遇到过
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
      <category term="Android" scheme="http://ibat.xyz/tags/Android/"/>
    
      <category term="Drawable" scheme="http://ibat.xyz/tags/Drawable/"/>
    
  </entry>
  
  <entry>
    <title>Android动态加载插件资源</title>
    <link href="http://ibat.xyz/2017/04/18/Android%E5%8A%A8%E6%80%81%E5%8A%A0%E8%BD%BD%E6%8F%92%E4%BB%B6%E8%B5%84%E6%BA%90/"/>
    <id>http://ibat.xyz/2017/04/18/Android动态加载插件资源/</id>
    <published>2017-04-18T08:30:28.000Z</published>
    <updated>2017-04-20T08:11:42.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="Android动态加载插件资源"><a href="#Android动态加载插件资源" class="headerlink" title="Android动态加载插件资源"></a>Android动态加载插件资源</h1><p>最近在看app的换肤功能。简单的来说就是动态读取插件apk中的资源，需要进行换肤的控件所用到的资源在主apk和插件apk中各维护了一份，且资源名称相同。<br>插件听起来高大上，但其实就是一个apk文件。所以我们所要做的，就是怎么样能让插件中的资源加载进本地，并且读取到。  </p>
<h1 id="Resource的创建"><a href="#Resource的创建" class="headerlink" title="Resource的创建"></a>Resource的创建</h1><p>在app内部加载资源使用的是context.getResources(),context中getResources()方法是一个抽象方法，具体的实现在ContextImpl类中。  </p>
<pre><code>Resources resources = packageInfo.getResources(mainThread);
</code></pre><p>参数packageInfo指向的是一个LoadedApk对象，这个LoadedApk对象描述的是当前正在启动的Activity组所属的Apk。  </p>
<p>进入到LoadedApk的getResources(mainThread)方法  </p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div></pre></td><td class="code"><pre><div class="line"><span class="function"><span class="keyword">public</span> Resources <span class="title">getResources</span><span class="params">(ActivityThread mainThread)</span> </span>&#123;</div><div class="line">        <span class="keyword">if</span> (mResources == <span class="keyword">null</span>) &#123;</div><div class="line">            mResources = mainThread.getTopLevelResources(mResDir, mSplitResDirs, mOverlayDirs,</div><div class="line">                    mApplicationInfo.sharedLibraryFiles, Display.DEFAULT_DISPLAY, <span class="keyword">this</span>);</div><div class="line">        &#125;</div><div class="line">        <span class="keyword">return</span> mResources;</div><div class="line">    &#125;</div></pre></td></tr></table></figure>
<p>LoadedApk类的成员函数getResources首先检查其成员变量mResources的值是否等于null。如果不等于的话，那么就会将它所指向的一个Resources对象返回给调用者，否则的话，就会调用参数mainThread的成员函数getTopLevelResources来获得这个Resources对象，然后再返回给调用者。 mainThread指向一个ActivityThread对象。</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div><div class="line">35</div><div class="line">36</div><div class="line">37</div><div class="line">38</div><div class="line">39</div><div class="line">40</div><div class="line">41</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">public</span> <span class="keyword">final</span> <span class="class"><span class="keyword">class</span> <span class="title">ActivityThread</span> </span>&#123;  </div><div class="line">    ......  </div><div class="line">    <span class="keyword">final</span> HashMap&lt;ResourcesKey, WeakReference&lt;Resources&gt; &gt; mActiveResources  </div><div class="line">            = <span class="keyword">new</span> HashMap&lt;ResourcesKey, WeakReference&lt;Resources&gt; &gt;();  </div><div class="line">      </div><div class="line">    <span class="function">Resources <span class="title">getTopLevelResources</span><span class="params">(String resDir, CompatibilityInfo compInfo)</span> </span>&#123;  </div><div class="line">        ResourcesKey key = <span class="keyword">new</span> ResourcesKey(resDir, compInfo.applicationScale);  </div><div class="line">        Resources r;  </div><div class="line">        <span class="keyword">synchronized</span> (mPackages) &#123;  </div><div class="line">            ......  </div><div class="line">            WeakReference&lt;Resources&gt; wr = mActiveResources.get(key);  </div><div class="line">            r = wr != <span class="keyword">null</span> ? wr.get() : <span class="keyword">null</span>;  </div><div class="line">            ......  </div><div class="line">            <span class="keyword">if</span> (r != <span class="keyword">null</span> &amp;&amp; r.getAssets().isUpToDate()) &#123;  </div><div class="line">                ......  </div><div class="line">                <span class="keyword">return</span> r;  </div><div class="line">            &#125;  </div><div class="line">        &#125;  </div><div class="line">        ......  </div><div class="line">        AssetManager assets = <span class="keyword">new</span> AssetManager();  </div><div class="line">        <span class="keyword">if</span> (assets.addAssetPath(resDir) == <span class="number">0</span>) &#123;  </div><div class="line">            <span class="keyword">return</span> <span class="keyword">null</span>;  </div><div class="line">        &#125;  </div><div class="line">        ......  </div><div class="line">        r = <span class="keyword">new</span> Resources(assets, metrics, getConfiguration(), compInfo);  </div><div class="line">        ......  </div><div class="line">        <span class="keyword">synchronized</span> (mPackages) &#123;  </div><div class="line">            WeakReference&lt;Resources&gt; wr = mActiveResources.get(key);  </div><div class="line">            Resources existing = wr != <span class="keyword">null</span> ? wr.get() : <span class="keyword">null</span>;  </div><div class="line">            <span class="keyword">if</span> (existing != <span class="keyword">null</span> &amp;&amp; existing.getAssets().isUpToDate()) &#123;  </div><div class="line">                <span class="comment">// Someone else already created the resources while we were  </span></div><div class="line">                <span class="comment">// unlocked; go ahead and use theirs.  </span></div><div class="line">                r.getAssets().close();  </div><div class="line">                <span class="keyword">return</span> existing;  </div><div class="line">            &#125;  </div><div class="line">            <span class="comment">// XXX need to remove entries when weak references go away  </span></div><div class="line">            mActiveResources.put(key, <span class="keyword">new</span> WeakReference&lt;Resources&gt;(r));  </div><div class="line">            <span class="keyword">return</span> r;  </div><div class="line">        &#125;  </div><div class="line">    &#125;  </div><div class="line">&#125;</div></pre></td></tr></table></figure>
<p>在其中创建了AssertManager对象，assets.addAssetPath(resDir)这句话的意思是把资源目录里的资源都加载到AssetManager对象中    如果我们把一个未安装的apk的路径传给这个方法，那么apk中的资源就被加载到AssetManager对象里面了。但它是一个隐藏方法，需要反射调用。有了AssertManager对象就能创建Resources对象了。  </p>
<h1 id="AssetManager介绍"><a href="#AssetManager介绍" class="headerlink" title="AssetManager介绍"></a>AssetManager介绍</h1><blockquote>
<p>Provides access to an application’s raw asset files; see Resources for the way most applications will want to retrieve their resource data. This class presents a lower-level API that allows you to open and read raw files that have been bundled with the application as a simple stream of bytes.  </p>
</blockquote>
<p>AssetManager提供了应用的原始资源，通过它可以让应用程序检索他们的资源数据。<br>在ResourcesImpl类中存在AssetManager的引用mAsset.举个例子看下Resources怎么通过AssetManager加载数据.看下Resources的getString()方法  </p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div></pre></td><td class="code"><pre><div class="line"><span class="function"><span class="keyword">public</span> String <span class="title">getString</span><span class="params">(@StringRes <span class="keyword">int</span> id)</span> <span class="keyword">throws</span> NotFoundException </span>&#123;</div><div class="line">        <span class="keyword">return</span> getText(id).toString();</div><div class="line">    &#125;</div><div class="line">    </div><div class="line">    </div><div class="line"><span class="function"><span class="keyword">public</span> CharSequence <span class="title">getText</span><span class="params">(@StringRes <span class="keyword">int</span> id)</span> <span class="keyword">throws</span> NotFoundException </span>&#123;</div><div class="line">        CharSequence res = mResourcesImpl.getAssets().getResourceText(id);</div><div class="line">        <span class="keyword">if</span> (res != <span class="keyword">null</span>) &#123;</div><div class="line">            <span class="keyword">return</span> res;</div><div class="line">        &#125;</div><div class="line">        <span class="keyword">throw</span> <span class="keyword">new</span> NotFoundException(<span class="string">"String resource ID #0x"</span></div><div class="line">                                    + Integer.toHexString(id));</div><div class="line">    &#125;</div></pre></td></tr></table></figure>
<p>Resources将资源id传给了AssetManager的getResourceText方法。从AssetManager中返回了资源数据。有兴趣大家可以深入研究一下，这里不做过多介绍。  接下来我们写一个小demo看看更换皮肤包的简单实现。  </p>
<h1 id="Demo"><a href="#Demo" class="headerlink" title="Demo"></a>Demo</h1><p>首先如果只加载本地皮肤包(带有皮肤资源的apk)的时候，我们将皮肤包放入assets文件夹内，再在初始化的时候加载进sdcard中。如果要下载皮肤包，则直接下载进sdcard指定目录中。我们现在只做本地皮肤包的更换。  </p>
<p>先进行初始化的操作：  </p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div><div class="line">35</div><div class="line">36</div><div class="line">37</div><div class="line">38</div><div class="line">39</div><div class="line">40</div><div class="line">41</div><div class="line">42</div><div class="line">43</div><div class="line">44</div><div class="line">45</div><div class="line">46</div><div class="line">47</div><div class="line">48</div><div class="line">49</div><div class="line">50</div></pre></td><td class="code"><pre><div class="line"><span class="comment">//先定义全局的名称和存储路径</span></div><div class="line"> <span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">final</span> String APK_NAME = <span class="string">"sample.apk"</span>;</div><div class="line"> <span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">final</span> String APK_DIR = Environment.</div><div class="line">            getExternalStorageDirectory() + File.separator + APK_NAME;</div><div class="line">	</div><div class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">init</span><span class="params">(Context context)</span> </span>&#123;</div><div class="line"></div><div class="line">        File pluginFile = <span class="keyword">new</span> File(APK_DIR);</div><div class="line">        <span class="keyword">if</span> (pluginFile.exists()) &#123;</div><div class="line">            pluginFile.delete();</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        InputStream is = <span class="keyword">null</span>;</div><div class="line">        FileOutputStream fos = <span class="keyword">null</span>;</div><div class="line"></div><div class="line">        <span class="keyword">try</span> &#123;</div><div class="line">            is = context.getAssets().open(APK_NAME);</div><div class="line">            fos = <span class="keyword">new</span> FileOutputStream(APK_DIR);</div><div class="line">            <span class="keyword">int</span> bytes;</div><div class="line">            <span class="keyword">byte</span>[] byteArr = <span class="keyword">new</span> <span class="keyword">byte</span>[<span class="number">1024</span> * <span class="number">4</span>];</div><div class="line">            <span class="keyword">while</span> ((bytes = is.read(byteArr, <span class="number">0</span>, <span class="number">1024</span> * <span class="number">4</span>)) != -<span class="number">1</span>) &#123;</div><div class="line">                fos.write(byteArr, <span class="number">0</span>, bytes);</div><div class="line">            &#125;</div><div class="line">			PackageManager mPm = context.getPackageManager();</div><div class="line">        	PackageInfo mInfo = mPm.getPackageArchiveInfo(APK_DIR, PackageManager.GET_ACTIVITIES);</div><div class="line">        	mSkinPackageName = mInfo.packageName;</div><div class="line"></div><div class="line">            AssetManager assetManager = AssetManager.class.newInstance();</div><div class="line">            Method method = assetManager.getClass().getMethod(<span class="string">"addAssetPath"</span>, String.class);</div><div class="line">            method.invoke(assetManager, pluginFile.getAbsolutePath());</div><div class="line"></div><div class="line">            mSuperResources = context.getResources();</div><div class="line">            mResources = <span class="keyword">new</span> Resources(assetManager, mSuperResources.getDisplayMetrics(),</div><div class="line">                    mSuperResources.getConfiguration());</div><div class="line"></div><div class="line">        &#125; <span class="keyword">catch</span> (Exception e) &#123;</div><div class="line">            e.printStackTrace();</div><div class="line">        &#125; <span class="keyword">finally</span> &#123;</div><div class="line">            <span class="keyword">try</span> &#123;</div><div class="line">                <span class="keyword">if</span> (is != <span class="keyword">null</span>) &#123;</div><div class="line">                    is.close();</div><div class="line">                &#125;</div><div class="line">                <span class="keyword">if</span> (fos != <span class="keyword">null</span>) &#123;</div><div class="line">                    fos.close();</div><div class="line">                &#125;</div><div class="line">            &#125; <span class="keyword">catch</span> (IOException e) &#123;</div><div class="line">                e.printStackTrace();</div><div class="line">            &#125;</div><div class="line">        &#125;</div><div class="line">    &#125;</div></pre></td></tr></table></figure>
<p>读取assets下的sample.apk，将其放进sdcard中。通过反射创建AssetManager,并调用addAssetPath方法，将apk的路径传入AssetManager中。再new 一个Resources对象，传入上步生成的AssetManager对象，这时就拿到了皮肤包apk的Resources对象。初始化完成。  </p>
<p>接下来在布局中放入一个TextView,动态替换TextView控件用到的资源。  </p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div></pre></td><td class="code"><pre><div class="line">&lt;TextView</div><div class="line">        android:id=<span class="string">"@+id/tv_name"</span></div><div class="line">        android:layout_width=<span class="string">"wrap_content"</span></div><div class="line">        android:layout_height=<span class="string">"wrap_content"</span></div><div class="line">        android:text=<span class="string">"@string/app_name"</span></div><div class="line">        android:textSize=<span class="string">"20sp"</span></div><div class="line">        android:layout_centerHorizontal=<span class="string">"true"</span></div><div class="line">        android:textColor=<span class="string">"@color/colorPrimaryDark"</span></div><div class="line">        android:background=<span class="string">"@mipmap/ic_launcher"</span></div><div class="line">        /&gt;</div></pre></td></tr></table></figure>
<p>代码实现</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div></pre></td><td class="code"><pre><div class="line">btnLoad = (Button) findViewById(R.id.btn_load);</div><div class="line">        tvName = (TextView) findViewById(R.id.tv_name);</div><div class="line">        btnLoad.setOnClickListener(<span class="keyword">new</span> View.OnClickListener() &#123;</div><div class="line">            <span class="meta">@Override</span></div><div class="line">            <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">onClick</span><span class="params">(View v)</span> </span>&#123;</div><div class="line"></div><div class="line">                tvName.setBackground(ResourceManager.getInstance()</div><div class="line">                        .loadMipmapResource(R.mipmap.ic_launcher));</div><div class="line"></div><div class="line">                tvName.setText(ResourceManager.getInstance()</div><div class="line">                        .loadStringResource(R.string.app_name));</div><div class="line"></div><div class="line">                tvName.setTextColor(ResourceManager.getInstance()</div><div class="line">                        .loadColorResource(R.color.colorPrimaryDark));</div><div class="line"></div><div class="line">            &#125;</div><div class="line">        &#125;);</div></pre></td></tr></table></figure>
<p>ok,这时候我们看下ResourceManager.getInstance().loadMipmapResource(R.mipmap.ic_launcher)的实现；</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div></pre></td><td class="code"><pre><div class="line"><span class="function"><span class="keyword">public</span> Drawable <span class="title">loadMipmapResource</span><span class="params">(<span class="keyword">int</span> resId)</span></span>&#123;</div><div class="line">       <span class="keyword">return</span> mResources.getDrawable(findTrueResId(resId,<span class="string">"mipmap"</span>));</div><div class="line">&#125;</div><div class="line"></div><div class="line">   <span class="comment">/**</span></div><div class="line">    * 找到插件app中rescource的真正id</div><div class="line">    * <span class="doctag">@param</span> resId 主app中的资源id</div><div class="line">    */</div><div class="line">   <span class="function"><span class="keyword">private</span> <span class="keyword">int</span> <span class="title">findTrueResId</span><span class="params">(<span class="keyword">int</span> resId,String defType)</span></span>&#123;</div><div class="line">       String entryName = mSuperResources.getResourceEntryName(resId);</div><div class="line">       Log.e(TAG, <span class="string">"entryName "</span> + entryName);</div><div class="line">       String resourceName = mSuperResources.getResourceName(resId);</div><div class="line">       Log.e(TAG, <span class="string">"resourceName "</span> + resourceName);</div><div class="line">       <span class="keyword">int</span> trueResId = mResources.getIdentifier(entryName, defType,mSkinPackageName);</div><div class="line">       Log.e(TAG, <span class="string">"trueResId "</span> + trueResId);</div><div class="line"></div><div class="line">       <span class="keyword">return</span> trueResId;</div><div class="line">   &#125;</div></pre></td></tr></table></figure>
<p>上面的代码,mSuperResources是当前apk的Resources对象，通过getResourceEntryName(resId)，拿到resId对应的名称.<br>还有一个方法，getResourceName，这个和getResourceEntryName的区别在于，getResourceName拿到的全名包括包名，getResourceEntryName拿到的是简短名称.这里我们使用getResourceEntryName方法。<br>调用皮肤包的Resources对象的getIdentifier方法，会返回资源在皮肤包中的真实id，将真实id拿到后，就可以调用getDrawable（trueId）来加载资源了。来看下打印出来的日志。  </p>
<pre><code>xyz.ibat.pluginsloader E/DONG: entryName ic_launcher
xyz.ibat.pluginsloader E/DONG: resourceName xyz.ibat.pluginsloader:mipmap/ic_launcher
xyz.ibat.pluginsloader E/DONG: trueResId 2130903047
</code></pre><p>加载string和color和上述方法原理相同。我们来看下最终效果。  </p>
<p>换肤前：</p>
<figure class="image-bubble">
                <div class="img-lightbox">
                    <div class="overlay"></div>
                    <img src="/img/Android动态加载资源1.png" alt="换肤前" title="">
                </div>
                <div class="image-caption">换肤前</div>
            </figure>  
<p>换肤后：  </p>
<p><img src="/img/Android动态加载资源2.png" alt="换肤后">  </p>
<h1 id="参考资料"><a href="#参考资料" class="headerlink" title="参考资料"></a>参考资料</h1><p><a href="http://blog.csdn.net/luoshengyang/article/details/8791064" target="_blank" rel="external">Android应用程序资源管理器（Asset Manager）的创建过程分析</a><br><a href="http://blog.csdn.net/singwhatiwanna/article/details/24532419" target="_blank" rel="external">Android源码分析-资源加载机制</a></p>
]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;Android动态加载插件资源&quot;&gt;&lt;a href=&quot;#Android动态加载插件资源&quot; class=&quot;headerlink&quot; title=&quot;Android动态加载插件资源&quot;&gt;&lt;/a&gt;Android动态加载插件资源&lt;/h1&gt;&lt;p&gt;最近在看app的换肤功能。简单的来说
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
      <category term="Android" scheme="http://ibat.xyz/tags/Android/"/>
    
      <category term="插件化" scheme="http://ibat.xyz/tags/%E6%8F%92%E4%BB%B6%E5%8C%96/"/>
    
  </entry>
  
  <entry>
    <title>自定义自适应弹出位置的PopupWindow</title>
    <link href="http://ibat.xyz/2017/04/12/%E8%87%AA%E5%AE%9A%E4%B9%89%E8%87%AA%E9%80%82%E5%BA%94%E5%BC%B9%E5%87%BA%E4%BD%8D%E7%BD%AE%E7%9A%84PopupWindow/"/>
    <id>http://ibat.xyz/2017/04/12/自定义自适应弹出位置的PopupWindow/</id>
    <published>2017-04-12T03:48:04.000Z</published>
    <updated>2017-04-12T12:32:28.000Z</updated>
    
    <content type="html"><![CDATA[<p>项目地址： <a href="https://github.com/JrDong/FitPopupWindow" target="_blank" rel="external">https://github.com/JrDong/FitPopupWindow</a><br>效果图：<br><img src="/img/popupwindow.gif" alt="效果图"></p>
<h1 id="简介"><a href="#简介" class="headerlink" title="简介"></a>简介</h1><p>项目是仿照网易新闻或者今日头条的不感兴趣功能。现在很多应用都加入了feed流，对自己不感兴趣的条目可以删除。<br>考虑到两个因素：1.每个item中叉号的位置并不是固定的，所以我们要根据点击的位置来判断弹框气泡的位置。2.list滑动时，当我想点击下面的item，则弹框应该向上弹出，反之亦然，所以要判断弹出的方向。<br>功能实现的话选择PopupWindow来实现。</p>
<h1 id="PopupWindow"><a href="#PopupWindow" class="headerlink" title="PopupWindow"></a>PopupWindow</h1><p>首先我们来自定义一个PopupWindow,先对PopupWindow进行初始化 </p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div></pre></td><td class="code"><pre><div class="line"></div><div class="line"><span class="function"><span class="keyword">private</span> <span class="keyword">void</span> <span class="title">init</span><span class="params">(Activity context, <span class="keyword">int</span> width, <span class="keyword">int</span> height)</span> </span>&#123;</div><div class="line">       <span class="keyword">this</span>.context = context;</div><div class="line">       </div><div class="line">       setWidth(width);</div><div class="line">       setHeight(height);</div><div class="line">       <span class="comment">//点击空白处让PopupWindow消失</span></div><div class="line">       setBackgroundDrawable(<span class="keyword">new</span> ColorDrawable(<span class="number">0x00000000</span>));</div><div class="line">       setOutsideTouchable(<span class="keyword">true</span>);</div><div class="line">       <span class="comment">//PopupWindow弹出后，所有的触屏和物理按键都有PopupWindows处理</span></div><div class="line">       setFocusable(<span class="keyword">true</span>);</div><div class="line">       <span class="comment">//设置消失的监听</span></div><div class="line">       setOnDismissListener(<span class="keyword">this</span>);</div><div class="line">       <span class="comment">//设置动画</span></div><div class="line">       setAnimationStyle(R.style.popp_anim);</div><div class="line">   &#125;</div></pre></td></tr></table></figure>
<p>初始化好之后，就需要进行计算弹出的位置了。定义PopupWindow弹窗位置有三个方法：</p>
<p>showAsDropDown(View anchor)：在某个控件正下方，无偏移  </p>
<p>showAsDropDown(View anchor, int xoff, int yoff)：相对某个控件的位置，有偏移</p>
<p>showAtLocation(View parent, int gravity, int x, int y)：第一个参数官方文档”a parent view to get the android.view.View.getWindowToken() token from“,这个parent的作用应该是调用其getWindowToken()方法获取窗口的Token,所以，只要是该窗口上的控件就可以了。gravity控制弹出位置，x,y分别控制偏移量。</p>
<p>接下来，计算偏移量：  </p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div><div class="line">35</div><div class="line">36</div><div class="line">37</div><div class="line">38</div><div class="line">39</div><div class="line">40</div></pre></td><td class="code"><pre><div class="line"><span class="comment">/**</span></div><div class="line">    * <span class="doctag">@param</span> anchorView  弹出window的view</div><div class="line">    * <span class="doctag">@param</span> contentView PopupWindow的内容布局</div><div class="line">    * <span class="doctag">@return</span> window显示的左上角的xOff, yOff坐标</div><div class="line">    */</div><div class="line">   <span class="keyword">protected</span> <span class="keyword">int</span>[] calculatePopWindowPos(<span class="keyword">final</span> View anchorView, <span class="keyword">final</span> View contentView) &#123;</div><div class="line">       <span class="keyword">final</span> <span class="keyword">int</span> windowPos[] = <span class="keyword">new</span> <span class="keyword">int</span>[<span class="number">2</span>];</div><div class="line">       <span class="keyword">final</span> <span class="keyword">int</span> anchorLoc[] = <span class="keyword">new</span> <span class="keyword">int</span>[<span class="number">2</span>];</div><div class="line">       <span class="comment">// 获取锚点View在屏幕上的左上角坐标位置</span></div><div class="line">       anchorView.getLocationOnScreen(anchorLoc);</div><div class="line">       <span class="keyword">final</span> <span class="keyword">int</span> anchorHeight = anchorView.getHeight();</div><div class="line">       <span class="keyword">final</span> <span class="keyword">int</span> anchorWidth = anchorView.getWidth();</div><div class="line">       mXCoordinate = anchorLoc[<span class="number">0</span>];</div><div class="line">       <span class="comment">// 获取屏幕的高宽</span></div><div class="line">       <span class="keyword">final</span> <span class="keyword">int</span> screenHeight = ScreenUtils.getScreenHeight(anchorView.getContext());</div><div class="line">       <span class="keyword">final</span> <span class="keyword">int</span> screenWidth = ScreenUtils.getScreenWidth(anchorView.getContext());</div><div class="line">       contentView.measure(View.MeasureSpec.UNSPECIFIED, View.MeasureSpec.UNSPECIFIED);</div><div class="line">       <span class="comment">// 计算contentView的高宽</span></div><div class="line">       <span class="keyword">int</span> windowHeight = contentView.getMeasuredHeight();</div><div class="line">       mWindowWidth = mWindowWidth &gt; <span class="number">0</span> ? mWindowWidth : contentView.getMeasuredWidth();</div><div class="line"></div><div class="line">       <span class="comment">// 判断需要向上弹出还是向下弹出,如果要改变弹出策略,改变此处即可</span></div><div class="line">       <span class="comment">// 目前是根据屏幕的一半进行判断</span></div><div class="line">       <span class="keyword">final</span> <span class="keyword">boolean</span> isNeedShowUp = (screenHeight - anchorLoc[<span class="number">1</span>] - anchorHeight &lt; screenHeight / <span class="number">2</span>);</div><div class="line"></div><div class="line">       <span class="comment">// 判断需要向左弹出还是向右弹出</span></div><div class="line">       <span class="keyword">final</span> <span class="keyword">boolean</span> isNeedShowLeft = (anchorLoc[<span class="number">0</span>] &lt; mWindowWidth / <span class="number">2</span>);</div><div class="line">       </div><div class="line">	 <span class="comment">//分别设置水平竖直弹出位置</span></div><div class="line">       setHorizontal(isNeedShowLeft ? FitPopupWindowLayout.LEFT : FitPopupWindowLayout.RIGHT);</div><div class="line">       setVertical(isNeedShowUp ? FitPopupWindowLayout.UP : FitPopupWindowLayout.DOWN);</div><div class="line">	 </div><div class="line">       windowPos[<span class="number">0</span>] = (screenWidth - mWindowWidth) / <span class="number">2</span>;</div><div class="line"></div><div class="line">       windowPos[<span class="number">1</span>] = isNeedShowUp ?</div><div class="line">               anchorLoc[<span class="number">1</span>] - windowHeight - PADDING - FitPopupWindowLayout.SHARP_HEIGHT</div><div class="line">               : anchorLoc[<span class="number">1</span>] + anchorHeight + PADDING;</div><div class="line"></div><div class="line">       <span class="keyword">return</span> windowPos;</div><div class="line">   &#125;</div></pre></td></tr></table></figure>
<p>设置View的方法</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div></pre></td><td class="code"><pre><div class="line">／**</div><div class="line">  * <span class="meta">@contentView</span> 内容布局</div><div class="line">  * <span class="meta">@anchorView</span> 目标view，比如叉号</div><div class="line">  *／</div><div class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">setView</span><span class="params">(View contentView, View anchorView)</span> </span>&#123;</div><div class="line">      <span class="keyword">this</span>.anchorView = anchorView;</div><div class="line">      <span class="comment">//计算偏移坐标</span></div><div class="line">      windowPos = calculatePopWindowPos(anchorView, contentView);</div><div class="line"> <span class="comment">//自定义带气泡的布局，最外层</span></div><div class="line">      mFitPopupWindowLayout = <span class="keyword">new</span> FitPopupWindowLayout(context);</div><div class="line">      RelativeLayout.LayoutParams layoutParams = <span class="keyword">new</span> RelativeLayout.LayoutParams(</div><div class="line">              ViewGroup.LayoutParams.MATCH_PARENT, getHeight() - FitPopupWindowLayout.SHARP_HEIGHT);</div><div class="line">      layoutParams.bottomMargin = FitPopupWindowLayout.SHARP_HEIGHT;</div><div class="line"></div><div class="line">      contentView.setLayoutParams(layoutParams);</div><div class="line">      <span class="comment">//给起泡布局设置方向，左上，右下等，并设置x方向上的偏移量</span></div><div class="line">      mFitPopupWindowLayout.setOrientation(getHorizontal(), getVertical(), getXCoordinate());</div><div class="line">      <span class="comment">//将内容布局添加到自定义的气泡布局中</span></div><div class="line">      mFitPopupWindowLayout.addView(contentView);</div><div class="line">      <span class="comment">//设置PopupWindow布局</span></div><div class="line">      setContentView(mFitPopupWindowLayout);</div><div class="line">  &#125;</div></pre></td></tr></table></figure>
<p>显示PopupWindow</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div></pre></td><td class="code"><pre><div class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">show</span><span class="params">()</span> </span>&#123;</div><div class="line">      showAtLocation(anchorView, Gravity.TOP | Gravity.END</div><div class="line">              , windowPos[<span class="number">0</span>], windowPos[<span class="number">1</span>]);</div><div class="line">      update();</div><div class="line">      <span class="comment">//弹出PopupWindow时让背景置灰,在onDismiss()回调中再将背景恢复</span></div><div class="line">      Window window = context.getWindow();</div><div class="line">      WindowManager.LayoutParams lp = window.getAttributes();</div><div class="line">      lp.alpha = <span class="number">0.7f</span>;</div><div class="line">      window.setAttributes(lp);</div><div class="line"></div><div class="line">  &#125;</div></pre></td></tr></table></figure>
<p>接下来我们看下自定义气泡布局</p>
<p>气泡布局由两部分组成，一个是圆角矩形，一个是贝塞尔曲线画成的尖角。我们直接看下onDraw方法</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div></pre></td><td class="code"><pre><div class="line"></div><div class="line"><span class="meta">@Override</span></div><div class="line">   <span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">onDraw</span><span class="params">(Canvas canvas)</span> </span>&#123;</div><div class="line">	 <span class="comment">//添加圆角矩形</span></div><div class="line">       mPath.addRoundRect(<span class="keyword">new</span> RectF(<span class="number">0</span>, <span class="number">0</span>, getMeasuredWidth(), getMeasuredHeight() - SHARP_HEIGHT)</div><div class="line">               , RECT_CORNER, RECT_CORNER, Path.Direction.CW);</div><div class="line">       mPath.addPath(makeSharpPath());</div><div class="line">       canvas.drawPath(mPath, mPaint);</div><div class="line">	 <span class="comment">//此处的mHorizontal和mVertical是上面PopupWindow计算出弹出位置后设置进来的</span></div><div class="line">       <span class="keyword">if</span> (mHorizontal == LEFT &amp;&amp; mVertical == UP) &#123;</div><div class="line">           setScaleX(<span class="number">1</span>);</div><div class="line">           setScaleY(<span class="number">1</span>);</div><div class="line">       &#125; <span class="keyword">else</span> <span class="keyword">if</span> (mHorizontal == LEFT &amp;&amp; mVertical == DOWN) &#123;</div><div class="line">           setScaleX(<span class="number">1</span>);</div><div class="line">           setScaleY(-<span class="number">1</span>);</div><div class="line">           scaleChild(<span class="number">1</span>, -<span class="number">1</span>);</div><div class="line">       &#125; <span class="keyword">else</span> <span class="keyword">if</span> (mHorizontal == RIGHT &amp;&amp; mVertical == UP) &#123;</div><div class="line">           setScaleX(-<span class="number">1</span>);</div><div class="line">           setScaleY(<span class="number">1</span>);</div><div class="line">           scaleChild(-<span class="number">1</span>, <span class="number">1</span>);</div><div class="line">       &#125; <span class="keyword">else</span> <span class="keyword">if</span> (mHorizontal == RIGHT &amp;&amp; mVertical == DOWN) &#123;</div><div class="line">           setScaleX(-<span class="number">1</span>);</div><div class="line">           setScaleY(-<span class="number">1</span>);</div><div class="line">           scaleChild(-<span class="number">1</span>, -<span class="number">1</span>);</div><div class="line">       &#125;</div><div class="line"></div><div class="line">   &#125;</div><div class="line">   </div><div class="line">    <span class="function"><span class="keyword">private</span> Path <span class="title">makeSharpPath</span><span class="params">()</span> </span>&#123;</div><div class="line">       mSharpPath.moveTo(mXoffset, getMeasuredHeight() - SHARP_HEIGHT);</div><div class="line">       mSharpPath.cubicTo(mXoffset, getMeasuredHeight(), mXoffset, getMeasuredHeight() - SHARP_HEIGHT,</div><div class="line">               SHARP_WIDTH + mXoffset, getMeasuredHeight() - SHARP_HEIGHT);</div><div class="line">       <span class="keyword">return</span> mSharpPath;</div><div class="line">   &#125;</div></pre></td></tr></table></figure>
<p>默认是按照左上角的位置画出的，也就是说先画出一个尖角在左上角的气泡view,<br>再根据偏移量用setScaleX，和 setScaleY进行旋转，但注意，旋转的话其中的子view也会跟着一起旋转，所以之后我们要再把其中的子view旋转回来。<br>mHorizontal和mVertical是上面PopupWindow计算出弹出位置后设置进来的。<br>这样一个带气泡的view就画好了。</p>
<p>我们再来整理一遍:<br>1.传入一个目标view，计算出PopupWindow的弹出方向，和x轴上的偏移量。<br>2.绘制一个气泡view，根据计算出来的方向和偏移量，画出气泡的方向。<br>3.传入一个内容布局，这个可以根据项目需求自定义。add到气泡ViewGroup中。<br>4.向上还是向下由showAtLocation方法决定，尖角的位置取决于通过目标view计算出来的方向和x轴偏移量，有了x轴的偏移量，就可以保证尖角在目标view的正下方。</p>
<p>以上就是自适应位置的全部思路，全部源码参考<a href="https://github.com/JrDong/FitPopupWindow" target="_blank" rel="external">https://github.com/JrDong/FitPopupWindow</a>    </p>
]]></content>
    
    <summary type="html">
    
      &lt;p&gt;项目地址： &lt;a href=&quot;https://github.com/JrDong/FitPopupWindow&quot; target=&quot;_blank&quot; rel=&quot;external&quot;&gt;https://github.com/JrDong/FitPopupWindow&lt;/a&gt;&lt;br&gt;效
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
      <category term="Android" scheme="http://ibat.xyz/tags/Android/"/>
    
      <category term="PopupWindow" scheme="http://ibat.xyz/tags/PopupWindow/"/>
    
  </entry>
  
  <entry>
    <title>分治法——快速排序，归并排序</title>
    <link href="http://ibat.xyz/2017/03/12/%E5%88%86%E6%B2%BB%E6%B3%95%E2%80%94%E2%80%94%E5%BF%AB%E9%80%9F%E6%8E%92%E5%BA%8F%EF%BC%8C%E5%BD%92%E5%B9%B6%E6%8E%92%E5%BA%8F/"/>
    <id>http://ibat.xyz/2017/03/12/分治法——快速排序，归并排序/</id>
    <published>2017-03-12T01:32:21.000Z</published>
    <updated>2017-03-12T09:08:28.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="分治法"><a href="#分治法" class="headerlink" title="分治法"></a>分治法</h1><blockquote>
<p>分治法是一种很重要的算法，也就是“分而治之”的意思，就是把一个复杂的问题分解成两个或者多个相似的子问题，直到最后子问题可以简单的直接求解，原问题的解即子问题的解的合并。</p>
</blockquote>
<p>比如二分搜索算法，排序算法中的快速排序和归并排序都属于分治法的一种。下面我们来看看归并排序和快速排序算法的实现。</p>
<h1 id="归并排序"><a href="#归并排序" class="headerlink" title="归并排序"></a>归并排序</h1><h2 id="简介"><a href="#简介" class="headerlink" title="简介"></a>简介</h2><figure class="image-bubble">
                <div class="img-lightbox">
                    <div class="overlay"></div>
                    <img src="/img/Merge-sort-anim2.gif" alt="MergeSort2" title="">
                </div>
                <div class="image-caption">MergeSort2</div>
            </figure>  
<p>(维基百科)<br><strong>归并排序</strong>（Merge sort）,是创建在归并操作上的一种有效的排序算法，效率为O(n log n)。最优时间复杂度，O(n),平均时间复杂度为O(n log n)。由上图我们可以了解到归并排序的过程。  </p>
<h2 id="实例分析"><a href="#实例分析" class="headerlink" title="实例分析"></a>实例分析</h2><p>以数组6 5 3 1 8 7 2 4为例。首先递归的将数组一分为2，并对子数组排序  </p>
<pre><code>[6, 5, 3, 1]  [8, 7, 2, 4]

[6, 5]  [3, 1]  [8, 7]  [2, 4]

[6], [5]  [4], [3]  [7], [8]  [2], [4]
</code></pre><p>然后向上回溯，将两个数组合并成有序数组</p>
<pre><code>[6], [5]  [4], [3]  [7], [8]  [2], [4]

[5, 6]  [3, 4]  [7, 8]  [2, 4]

[3, 4, 5, 6] [2, 4, 7, 8]           

[1, 2, 3, 4, 5, 6, 7, 8]
</code></pre><p>动图如下所示<br><img src="/img/Merge-sort-anim.gif" alt="MergeSort"><br>(维基百科)</p>
<h2 id="两个有序数组排序"><a href="#两个有序数组排序" class="headerlink" title="两个有序数组排序"></a>两个有序数组排序</h2><figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div></pre></td><td class="code"><pre><div class="line"><span class="comment">/**</span></div><div class="line">    *</div><div class="line">    * <span class="doctag">@param</span> a 有序数组a</div><div class="line">    * <span class="doctag">@param</span> b 有序数组b</div><div class="line">    * <span class="doctag">@param</span> result 结果数组</div><div class="line">    */</div><div class="line">   <span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">merge2</span><span class="params">(<span class="keyword">int</span>[] a,<span class="keyword">int</span> [] b, <span class="keyword">int</span>[] result)</span></span>&#123;</div><div class="line"></div><div class="line">       <span class="keyword">int</span> i = <span class="number">0</span> , j = <span class="number">0</span> , k = <span class="number">0</span> ;</div><div class="line">       <span class="keyword">while</span> (i &lt; a.length &amp;&amp; j &lt; b.length)&#123;</div><div class="line">           <span class="keyword">if</span> (a[i] &lt; b[j])&#123;</div><div class="line">               result[k++] = a[i++];</div><div class="line">           &#125;<span class="keyword">else</span> &#123;</div><div class="line">               result[k++] = b[j++];</div><div class="line">           &#125;</div><div class="line">       &#125;</div><div class="line"></div><div class="line">       <span class="keyword">while</span> (i &lt; a.length)&#123;</div><div class="line">           result[k++] = a[i++];</div><div class="line">       &#125;</div><div class="line"></div><div class="line">       <span class="keyword">while</span> (j &lt; b.length)&#123;</div><div class="line">           result[k++] = b[j++];</div><div class="line">       &#125;</div><div class="line">       print(result);</div><div class="line">   &#125;</div></pre></td></tr></table></figure>
<p>看会了两个有序数组的排序,则知道了如何实现归并排序</p>
<h2 id="Java代码实现"><a href="#Java代码实现" class="headerlink" title="Java代码实现"></a>Java代码实现</h2><figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div></pre></td><td class="code"><pre><div class="line"><span class="function"><span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">merge</span><span class="params">(<span class="keyword">int</span>[] arr, <span class="keyword">int</span>[] result, <span class="keyword">int</span> start, <span class="keyword">int</span> end)</span> </span>&#123;</div><div class="line"></div><div class="line">        <span class="keyword">if</span> (start &gt;= end) <span class="keyword">return</span>;</div><div class="line"></div><div class="line">        <span class="keyword">int</span> center = (start + end) / <span class="number">2</span>;</div><div class="line">        <span class="keyword">int</span> start1 = start, end1 = center;</div><div class="line">        <span class="keyword">int</span> start2 = center + <span class="number">1</span>, end2 = end;</div><div class="line">        merge(arr, result, start1, end1);</div><div class="line">        merge(arr, result, start2, end2);</div><div class="line">        <span class="keyword">int</span> k = start1;</div><div class="line">        <span class="keyword">while</span> (start1 &lt;= end1 &amp;&amp; start2 &lt;= end2) &#123;</div><div class="line">            <span class="keyword">if</span> (arr[start1] &lt; arr[start2]) &#123;</div><div class="line">                result[k++] = arr[start1++];</div><div class="line">            &#125; <span class="keyword">else</span> &#123;</div><div class="line">                result[k++] = arr[start2++];</div><div class="line">            &#125;</div><div class="line">        &#125;</div><div class="line">        <span class="keyword">while</span> (start1 &lt;= end1) &#123;</div><div class="line">            result[k++] = arr[start1++];</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        <span class="keyword">while</span> (start2 &lt;= end2) &#123;</div><div class="line">            result[k++] = arr[start2++];</div><div class="line">        &#125;</div><div class="line">        <span class="keyword">for</span> (k = start; k &lt;= end; k++) &#123;</div><div class="line">            arr[k] = result[k];</div><div class="line">        &#125;</div><div class="line">        print(arr);</div><div class="line"></div><div class="line">    &#125;</div></pre></td></tr></table></figure>
<h1 id="快速排序"><a href="#快速排序" class="headerlink" title="快速排序"></a>快速排序</h1><h2 id="简介-1"><a href="#简介-1" class="headerlink" title="简介"></a>简介</h2><figure class="image-bubble">
                <div class="img-lightbox">
                    <div class="overlay"></div>
                    <img src="/img/Sorting_quicksort_anim.gif" alt="quickSort" title="">
                </div>
                <div class="image-caption">quickSort</div>
            </figure>  
<p>(使用快速排序法对一列数字进行排序的过程——维基百科)  </p>
<p><strong>快速排序</strong>（Quicksort），是一种排序算法，最坏情况复杂度：Ο(n2)，最优时间复杂度：Ο(n log n)，平均时间复杂度：Ο(n log n)。快速排序的基本思想也是用了分治法的思想：找出一个元素X，在一趟排序中，使X左边的数都比X小，X右边的数都比X要大。然后再分别对X左边的数组和X右边的数组进行排序，直到数组不能分割为止。   </p>
<h2 id="具体操作"><a href="#具体操作" class="headerlink" title="具体操作"></a>具体操作</h2><p>ok,我们来看一下具体操作：  </p>
<p>1.设置一个长度为n的数组A,定义两个变量i = 0,j = n - 1;<br>2.从数组中挑选出一个元素作为基准元素，复制给key；<br>3.从j开始从后向前搜索，j–,找到比key小的值，将A[j]与A[i]互换；<br>4.从i 开始向后搜索，i++,找到比key大的值，将A[i]与A[j]互换；<br>5.递归的，重复2，3，4步，直到i == j ;  </p>
<p>举个栗子：  </p>
<ul>
<li>存在一个数组A：6 2 7 3 8 9  ,创建i = 0 ; j = 5,选择一个基准元素 k = 6  </li>
<li>j 从右向左查找比k小的元素，发现，当 j = 3 时，发现元素3比k小，则另A[i] 与 A[j]交换，得到3 2 7 6 8 9;  </li>
<li>i 从左向右进行查找，当 i = 2时，发现元素 7 比k大，则另A[i] 与A[j]进行交换，得到 3 2 6 7 8 9;  </li>
<li>接着，再减小j，重复上面的循环。  </li>
<li>但是我们发现，在本例中，一次循环后j与i就相等了，他们的下标同时指向了2.这时候，我们就进行分组，将3 2分为一组，7 8 9分为一组继续上述的比较，最终得到排序好的数组。</li>
</ul>
<h2 id="Java代码实现-1"><a href="#Java代码实现-1" class="headerlink" title="Java代码实现"></a>Java代码实现</h2><figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div><div class="line">35</div></pre></td><td class="code"><pre><div class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">quickSort</span><span class="params">(<span class="keyword">int</span>[] arr, <span class="keyword">int</span> start, <span class="keyword">int</span> end)</span> </span>&#123;</div><div class="line">        <span class="keyword">if</span> (start &gt;= end)</div><div class="line">            <span class="keyword">return</span>;</div><div class="line"></div><div class="line">        <span class="keyword">int</span> mid = arr[end];</div><div class="line">        <span class="keyword">int</span> left = start;</div><div class="line">        <span class="keyword">int</span> right = end - <span class="number">1</span>;</div><div class="line"></div><div class="line">        <span class="keyword">while</span> (left &lt; right) &#123;</div><div class="line">            <span class="keyword">while</span> (arr[left] &lt;= mid &amp;&amp; left &lt; right) &#123;</div><div class="line">                left++;</div><div class="line">            &#125;</div><div class="line">            <span class="keyword">while</span> (arr[right] &gt;= mid &amp;&amp; left &lt; right) &#123;</div><div class="line">                right--;</div><div class="line">            &#125;</div><div class="line">            swap(arr, left, right);</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        <span class="keyword">if</span> (arr[left] &gt;= arr[end]) &#123;</div><div class="line">            swap(arr, left, end);</div><div class="line">        &#125; <span class="keyword">else</span> &#123;</div><div class="line">            left++;</div><div class="line">        &#125;</div><div class="line">        quickSort(arr, start, left - <span class="number">1</span>);</div><div class="line">        quickSort(arr, left + <span class="number">1</span>, end);</div><div class="line"></div><div class="line">        print(arr);</div><div class="line">    &#125;</div><div class="line">    </div><div class="line">    </div><div class="line">    <span class="function"><span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">swap</span><span class="params">(<span class="keyword">int</span>[] arr, <span class="keyword">int</span> x, <span class="keyword">int</span> y)</span> </span>&#123;</div><div class="line">        <span class="keyword">int</span> temp = arr[x];</div><div class="line">        arr[x] = arr[y];</div><div class="line">        arr[y] = temp;</div><div class="line">    &#125;</div></pre></td></tr></table></figure>
<h1 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h1><p>可以看出分治法的策略还是递归的去解决问题，基本分为三个步骤：  </p>
<p>分解：将原问题分解为若干个规模较小，相互独立，与原问题形式相同的子问题；  </p>
<p>解决：若子问题规模较小而容易被解决则直接解，否则递归地解各个子问题；  </p>
<p>合并：将各个子问题的解合并为原问题的解。  </p>
]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;分治法&quot;&gt;&lt;a href=&quot;#分治法&quot; class=&quot;headerlink&quot; title=&quot;分治法&quot;&gt;&lt;/a&gt;分治法&lt;/h1&gt;&lt;blockquote&gt;
&lt;p&gt;分治法是一种很重要的算法，也就是“分而治之”的意思，就是把一个复杂的问题分解成两个或者多个相似的子问题，直
    
    </summary>
    
      <category term="算法" scheme="http://ibat.xyz/categories/%E7%AE%97%E6%B3%95/"/>
    
    
  </entry>
  
  <entry>
    <title>单例模式--双重检验锁真的线程安全吗</title>
    <link href="http://ibat.xyz/2017/03/10/%E5%8D%95%E4%BE%8B%E6%A8%A1%E5%BC%8F--%E5%8F%8C%E9%87%8D%E6%A3%80%E9%AA%8C%E9%94%81%E7%9C%9F%E7%9A%84%E7%BA%BF%E7%A8%8B%E5%AE%89%E5%85%A8%E5%90%97/"/>
    <id>http://ibat.xyz/2017/03/10/单例模式--双重检验锁真的线程安全吗/</id>
    <published>2017-03-10T14:56:48.000Z</published>
    <updated>2017-03-10T17:19:57.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="单例模式–双重检验锁真的线程安全吗"><a href="#单例模式–双重检验锁真的线程安全吗" class="headerlink" title="单例模式–双重检验锁真的线程安全吗"></a>单例模式–双重检验锁真的线程安全吗</h1><p>单例模式是我们最熟悉不过的一种设计模式，用来保证内存中只有一个对象的实例。虽然容易，但里面的坑也有很多，比如双重检验锁模式(double checked locking pattern)真的是线程安全的吗？ </p>
<h2 id="起因"><a href="#起因" class="headerlink" title="起因"></a>起因</h2><p>在对项目进行PMD静态代码检测时，遇到了这样一个问题  </p>
<blockquote>
<p>Partially created objects can be returned by the Double Checked Locking pattern when used in Java. An optimizing JRE may assign a reference to the baz variable before it calls the constructor of the object the reference points to.  </p>
<p>Note: With Java 5, you can make Double checked locking work, if you declare the variable to be volatile.</p>
</blockquote>
<p>大概意思是，使用双重检验锁模式，可能会返回一个部分初始化的对象。可能大家有些疑虑，什么是部分初始化的对象，我们下面继续分析  </p>
<h2 id="什么是双重检验锁模式"><a href="#什么是双重检验锁模式" class="headerlink" title="什么是双重检验锁模式"></a>什么是双重检验锁模式</h2><figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div></pre></td><td class="code"><pre><div class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">static</span> Singleton <span class="title">getSingleton</span><span class="params">()</span> </span>&#123;</div><div class="line">    <span class="keyword">if</span> (instance == <span class="keyword">null</span>) &#123;                        </div><div class="line">        <span class="keyword">synchronized</span> (Singleton.class) &#123;</div><div class="line">            <span class="keyword">if</span> (instance == <span class="keyword">null</span>) &#123;                 </div><div class="line">                instance = <span class="keyword">new</span> Singleton();</div><div class="line">            &#125;</div><div class="line">        &#125;</div><div class="line">    &#125;</div><div class="line">    <span class="keyword">return</span> instance ;</div><div class="line">&#125;</div></pre></td></tr></table></figure>
<p>我们看到，在同步代码块的内部和外部都判断了instance == null，这时因为，可能会有多个线程同时进入到同步代码块外的if判断中，如果在同步代码块内部不进行判空的话，可能会初始化多个实例。  </p>
<h2 id="问题所在"><a href="#问题所在" class="headerlink" title="问题所在"></a>问题所在</h2><p>这种写法看似完美无缺，但它却是有问题的，或者说它并不担保一定完美无缺。主要原因在于instance = new Singleton();并不是原子性的操作。<br>创建一个对象可以分为三部：  </p>
<pre><code>1.分配对象的内存空间
2.初始化对象
3.设置instance指向刚分配的内存地址
当instance指向分配地址时，instance不为空
</code></pre><p>但是，2、3部之间，可能会被重排序，造成创建对象顺序变为1-3-2.试想一个场景：<br>线程A第一次创建对象Singleton，对象创建顺序为1-3-2；<br>当给instance分配完内存后，这时来了一个线程B调用了getSingleton()方法<br>这时候进行instance == null的判断，发现instance并不为null。<br>但注意这时候instance并没有初始化对象，线程B则会将这个未初始化完成的对象返回。那B线程使用instance时就可能会出现问题，这就是双重检查锁问题所在。</p>
<h2 id="使用volatile"><a href="#使用volatile" class="headerlink" title="使用volatile"></a>使用volatile</h2><p>对于上述的问题，我们可以通过把instance声明为volatile型来解决  </p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">Singleton</span></span>&#123;</div><div class="line">	<span class="keyword">private</span> <span class="keyword">volatile</span> <span class="keyword">static</span> Singleton instance;</div><div class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">static</span> Singleton <span class="title">getSingleton</span><span class="params">()</span> </span>&#123;</div><div class="line">	    <span class="keyword">if</span> (instance == <span class="keyword">null</span>) &#123;                        </div><div class="line">	        <span class="keyword">synchronized</span> (Singleton.class) &#123;</div><div class="line">	            <span class="keyword">if</span> (instance == <span class="keyword">null</span>) &#123;                 </div><div class="line">	                instance = <span class="keyword">new</span> Singleton();</div><div class="line">	            &#125;</div><div class="line">	        &#125;</div><div class="line">	    &#125;</div><div class="line">	    <span class="keyword">return</span> instance ;</div><div class="line">	&#125;</div><div class="line">&#125;</div></pre></td></tr></table></figure>
<p>但是必须在JDK5版本以上使用。</p>
<h2 id="静态内部类"><a href="#静态内部类" class="headerlink" title="静态内部类"></a>静态内部类</h2><figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">Singleton</span> </span>&#123;  </div><div class="line">    <span class="keyword">private</span> <span class="keyword">static</span> <span class="class"><span class="keyword">class</span> <span class="title">SingletonHolder</span> </span>&#123;  </div><div class="line">        <span class="keyword">private</span> <span class="keyword">static</span> <span class="keyword">final</span> Singleton INSTANCE = <span class="keyword">new</span> Singleton();  </div><div class="line">    &#125;  </div><div class="line">    <span class="function"><span class="keyword">private</span> <span class="title">Singleton</span> <span class="params">()</span></span>&#123;&#125;  </div><div class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">final</span> Singleton <span class="title">getInstance</span><span class="params">()</span> </span>&#123;  </div><div class="line">        <span class="keyword">return</span> SingletonHolder.INSTANCE; </div><div class="line">    &#125;  </div><div class="line">&#125;</div></pre></td></tr></table></figure>
<p>这种写法是目前比较推荐的一种写法，采用静态内部类的方式，即实现了懒加载又不会出现线程安全问题。而且减少了synchronized的开销。</p>
<h2 id="Learn-more"><a href="#Learn-more" class="headerlink" title="Learn more"></a>Learn more</h2><p><a href="http://www.infoq.com/cn/articles/double-checked-locking-with-delay-initialization" target="_blank" rel="external">双重检查锁定与延迟初始化</a><br><a href="https://pmd.github.io/pmd-5.5.4/pmd-java/rules/java/basic.html" target="_blank" rel="external">PMD-DoubleCheckedLocking</a><br><a href="http://www.javaworld.com/article/2074979/java-concurrency/double-checked-locking--clever--but-broken.html" target="_blank" rel="external">Double-checked locking: Clever, but broken</a></p>
]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;单例模式–双重检验锁真的线程安全吗&quot;&gt;&lt;a href=&quot;#单例模式–双重检验锁真的线程安全吗&quot; class=&quot;headerlink&quot; title=&quot;单例模式–双重检验锁真的线程安全吗&quot;&gt;&lt;/a&gt;单例模式–双重检验锁真的线程安全吗&lt;/h1&gt;&lt;p&gt;单例模式是我们最熟悉
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
  </entry>
  
  <entry>
    <title>浅谈HashMap中的hash算法</title>
    <link href="http://ibat.xyz/2017/02/16/%E6%B5%85%E8%81%8AHashMap%E4%B8%AD%E7%9A%84hash%E7%AE%97%E6%B3%95/"/>
    <id>http://ibat.xyz/2017/02/16/浅聊HashMap中的hash算法/</id>
    <published>2017-02-16T14:19:15.000Z</published>
    <updated>2017-03-05T08:40:39.000Z</updated>
    
    <content type="html"><![CDATA[<h2 id="浅谈HashMap中的hash算法"><a href="#浅谈HashMap中的hash算法" class="headerlink" title="浅谈HashMap中的hash算法"></a>浅谈HashMap中的hash算法</h2><p>HashMap是我们常见的一种数据结构，实现Map接口，用来存储键值对,允许null键/值、非同步、不保证有序(比如插入的顺序)。那HashMap中最核心的部分就是哈希函数，又称散列函数。也就是说，哈希函数是通过把key的hash值映射到数组中的一个位置来进行访问。比如：  </p>
<pre><code>存在一组哈希值 10，13，7，5，4，20
存在一个长度为10的数组 arrays
定义一个hash函数 int index = h % arrays.length; 

10 % 10 = 0 那么 哈希值为10的对象放在数组索引为0的位置上；
13 % 10 = 3 那么 哈希值为13的对象放在数组索引为3的位置上；
......
20 % 10 = 0 那么 哈希值为13的对象放在数组索引为0的位置上；
</code></pre><p>这时候大家看出了一个问题，哈希值为10的对象和哈希值为20的对象，放在了一个索引上。发生了碰撞，那么怎么解决这样碰撞呢，有很多种方式，这里不展开叙述。HashMap中维护了一个链表组成的数组。如果冲突的话就添加到链表中，下面来看下hashmap中的hash算法，以Java8源码为例。</p>
<pre><code>static final int hash(Object key) {
        int h;
        return (key == null) ? 0 : (h = key.hashCode()) ^ (h &gt;&gt;&gt; 16);
    }
</code></pre><p>其中，key.hashCode（）是Key自带的hashCode()方法，返回一个int类型的散列值。我们大家知道，32位带符号的int表值范围从-2147483648到2147483648。这样只要hash函数松散的话，一般是很难发生碰撞的，因为HashMap的初始容量只有16。但是这样的散列值我们是不能直接拿来用的。用之前需要对数组的长度取模运算。得到余数才是索引值。我们来看下HashMap中怎么实现的。  </p>
<pre><code>int index = hash &amp; (arrays.length-1);
</code></pre><p>那么这也就明白了为什么HashMap的数组长度是2的整数幂。比如以初始长度为16为例，16-1 = 15，15的二进制数位00000000 00000000 00001111。可以看出一个基数二进制最后一位必然位1，当与一个hash值进行与运算时，最后一位可能是0也可能是1。但偶数与一个hash值进行与运算最后一位必然为0，造成有些位置永远映射不上值。<br>但是这时，又出现了一个问题，即使散列函数很松散，但只取最后几位碰撞也会很严重。这时候hash算法的价值就体现出来了，<br><img src="/img/hash算法1.png" alt="扰动函数"><br>hashCode右移16位，正好是32bit的一半。与自己本身做异或操作（相同为0，不同为1）。就是为了混合哈希值的高位和地位，增加低位的随机性。并且混合后的值也变相保持了高位的特征。</p>
<p>HashMap中用到的编码思想确实很值得我们学习。HashMap在Java1.8后又进行了优化，比如引入红黑树的数据结构和扩容的优化等。有机会我们再结合Java1.8聊聊，HashMap get()和put（）实现原理，装载因子，resize()方法还有红黑树等。</p>
]]></content>
    
    <summary type="html">
    
      &lt;h2 id=&quot;浅谈HashMap中的hash算法&quot;&gt;&lt;a href=&quot;#浅谈HashMap中的hash算法&quot; class=&quot;headerlink&quot; title=&quot;浅谈HashMap中的hash算法&quot;&gt;&lt;/a&gt;浅谈HashMap中的hash算法&lt;/h2&gt;&lt;p&gt;HashMap是我们
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
  </entry>
  
  <entry>
    <title>TextView进阶用法</title>
    <link href="http://ibat.xyz/2017/02/06/TextView%E8%BF%9B%E9%98%B6%E7%94%A8%E6%B3%95/"/>
    <id>http://ibat.xyz/2017/02/06/TextView进阶用法/</id>
    <published>2017-02-06T15:30:15.000Z</published>
    <updated>2017-02-07T14:04:04.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="TextView进阶用法"><a href="#TextView进阶用法" class="headerlink" title="TextView进阶用法"></a>TextView进阶用法</h1><p>在Android中TextView是我们最熟悉不过的控件了，但是它的进阶用法你知道多少呢？下面就来聊一聊TextView的进阶用法。</p>
<h3 id="1-显示多种颜色"><a href="#1-显示多种颜色" class="headerlink" title="1.显示多种颜色"></a>1.显示多种颜色</h3><p>在做项目中经常会遇到一行字显示多种颜色的需求。用两个或多个TextView也可以实现，但这样比较费事，而且可能还要多一级布局嵌套。接下来我们需要用到SpannableStringBuilder这个类。</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div></pre></td><td class="code"><pre><div class="line"></div><div class="line">TextView textView = (TextView) findViewById(R.id.textview);</div><div class="line"></div><div class="line">String text = <span class="string">"TextView进阶用法"</span>;</div><div class="line"></div><div class="line">SpannableStringBuilder ssb = <span class="keyword">new</span> SpannableStringBuilder(text);</div><div class="line">ssb.setSpan(<span class="keyword">new</span> ForegroundColorSpan(Color.RED),<span class="number">0</span>,<span class="number">8</span>, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);</div><div class="line">ssb.setSpan(<span class="keyword">new</span> ForegroundColorSpan(Color.GREEN),<span class="number">8</span>,text.length(),Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);</div><div class="line"></div><div class="line">textView.setText(ssb);</div></pre></td></tr></table></figure>
<p>效果如下:<br><img src="/img/TextView进阶用法-1.png" alt="textview多种颜色"><br>SpannableStringBuilder类实现了CharSequence接口，所以可以直接通过setText()设置值，它更像一个StringBuilder，同时也有append()方法。这样的话无论要指定多少颜色，都可以通过setSpan()来根据字符串的索引长度来解决。<br>注意：   </p>
<pre><code>1.参数start为闭区间，end为开区间。即本例中的0，8实际代表从0～7的长度。  
2.int flags：取值有如下四个  
  Spannable.SPAN_EXCLUSIVE_EXCLUSIVE：前后都不包括，即在指定范围的前面和后面插入新字符都不会应用新样式   
  Spannable.SPAN_EXCLUSIVE_INCLUSIVE：前面不包括，后面包括。即仅在范围字符的后面插入新字符时会应用新样式  
  Spannable.SPAN_INCLUSIVE_EXCLUSIVE：前面包括，后面不包括。  
  Spannable.SPAN_INCLUSIVE_INCLUSIVE：前后都包括。 

大家可以自己试下取不同flags时的效果，可以用EditText试验。  
</code></pre><h3 id="2-显示不同大小"><a href="#2-显示不同大小" class="headerlink" title="2.显示不同大小"></a>2.显示不同大小</h3><p>将ForegroundColorSpan改为AbsoluteSizeSpan。  </p>
<pre><code>ssb.setSpan(new AbsoluteSizeSpan(80),0,8,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
</code></pre><h3 id="3-删除线（StrikethroughSpan）"><a href="#3-删除线（StrikethroughSpan）" class="headerlink" title="3.删除线（StrikethroughSpan）"></a>3.删除线（StrikethroughSpan）</h3><pre><code>ssb.setSpan(new StrikethroughSpan(),0,8,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
</code></pre><h3 id="4-下划线（UnderlineSpan）"><a href="#4-下划线（UnderlineSpan）" class="headerlink" title="4.下划线（UnderlineSpan）"></a>4.下划线（UnderlineSpan）</h3><pre><code>ssb.setSpan(new UnderlineSpan(),0,8,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
</code></pre><h3 id="5-加粗斜体（StyleSpan）"><a href="#5-加粗斜体（StyleSpan）" class="headerlink" title="5.加粗斜体（StyleSpan）"></a>5.加粗斜体（StyleSpan）</h3><pre><code>粗体：
ssb.setSpan(new StyleSpan(Typeface.BOLD),0,8,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
斜体：
ssb.setSpan(new StyleSpan(Typeface.ITALIC),0,8,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
</code></pre><h3 id="6-设置点击事件"><a href="#6-设置点击事件" class="headerlink" title="6.设置点击事件"></a>6.设置点击事件</h3><pre><code>ssb.setSpan(new ClickableSpan() {
        @Override
        public void onClick(View widget) {
            Toast.makeText(getApplicationContext(),&quot;被点击了&quot;,Toast.LENGTH_SHORT).show();
        }
    },0,8,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

//须调用此方法，不然点击无效
textView.setMovementMethod(LinkMovementMethod.getInstance());
</code></pre><p>最终效果如下：<br><img src="/img/TextView进阶用法-2.png" alt="textview多种颜色"> </p>
<p>当然，如果你想及设置点击又设置颜色或下划线的话，ClickableSpan也提供了一个回调方法来设置颜色下划线等属性。</p>
<pre><code>@Override
public void updateDrawState(TextPaint ds) {
            ds.setColor(Color.RED);
            ds.setUnderlineText(true);
}
</code></pre><h3 id="附上完整代码"><a href="#附上完整代码" class="headerlink" title="附上完整代码"></a>附上完整代码</h3><figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div></pre></td><td class="code"><pre><div class="line">TextView textView = (TextView) findViewById(R.id.textview);</div><div class="line"></div><div class="line">      String text = <span class="string">"TextView进阶用法"</span>;</div><div class="line"></div><div class="line">      SpannableStringBuilder ssb = <span class="keyword">new</span> SpannableStringBuilder(text);</div><div class="line">      ssb.setSpan(<span class="keyword">new</span> ForegroundColorSpan(Color.RED),<span class="number">0</span>,<span class="number">8</span>, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);</div><div class="line">      ssb.setSpan(<span class="keyword">new</span> ForegroundColorSpan(Color.GREEN),<span class="number">8</span>,text.length(),Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);</div><div class="line">      ssb.setSpan(<span class="keyword">new</span> AbsoluteSizeSpan(<span class="number">80</span>),<span class="number">0</span>,<span class="number">8</span>,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);</div><div class="line">      ssb.setSpan(<span class="keyword">new</span> StrikethroughSpan(),<span class="number">0</span>,<span class="number">8</span>,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);</div><div class="line">      ssb.setSpan(<span class="keyword">new</span> UnderlineSpan(),<span class="number">0</span>,<span class="number">8</span>,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);</div><div class="line">      ssb.setSpan(<span class="keyword">new</span> StyleSpan(Typeface.BOLD),<span class="number">0</span>,<span class="number">8</span>,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);</div><div class="line">      ssb.setSpan(<span class="keyword">new</span> StyleSpan(Typeface.ITALIC),<span class="number">0</span>,<span class="number">8</span>,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);</div><div class="line"></div><div class="line">      ssb.setSpan(<span class="keyword">new</span> ClickableSpan() &#123;</div><div class="line">          <span class="meta">@Override</span></div><div class="line">          <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">onClick</span><span class="params">(View widget)</span> </span>&#123;</div><div class="line">              Toast.makeText(getApplicationContext(),<span class="string">"被点击了"</span>,Toast.LENGTH_SHORT).show();</div><div class="line">          &#125;</div><div class="line"></div><div class="line">          <span class="meta">@Override</span></div><div class="line">          <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">updateDrawState</span><span class="params">(TextPaint ds)</span> </span>&#123;</div><div class="line">              ds.setColor(Color.RED);</div><div class="line">              ds.setUnderlineText(<span class="keyword">true</span>);</div><div class="line">          &#125;</div><div class="line"></div><div class="line">      &#125;,<span class="number">0</span>,<span class="number">8</span>,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);</div><div class="line"></div><div class="line">      <span class="comment">//须调用此方法，不然点击无效</span></div><div class="line">      textView.setMovementMethod(LinkMovementMethod.getInstance());</div><div class="line">      textView.setText(ssb);</div></pre></td></tr></table></figure>
<p>这样就不用担心一段话要写多个TextView的问题了。一个TextView统统搞定！</p>
]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;TextView进阶用法&quot;&gt;&lt;a href=&quot;#TextView进阶用法&quot; class=&quot;headerlink&quot; title=&quot;TextView进阶用法&quot;&gt;&lt;/a&gt;TextView进阶用法&lt;/h1&gt;&lt;p&gt;在Android中TextView是我们最熟悉不过的控件了，
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
  </entry>
  
  <entry>
    <title>2017年，我的小目标</title>
    <link href="http://ibat.xyz/2017/02/05/2017%E5%B9%B4%EF%BC%8C%E6%88%91%E7%9A%84%E5%B0%8F%E7%9B%AE%E6%A0%87/"/>
    <id>http://ibat.xyz/2017/02/05/2017年，我的小目标/</id>
    <published>2017-02-05T13:34:21.000Z</published>
    <updated>2017-03-05T07:06:53.000Z</updated>
    
    <content type="html"><![CDATA[<p>2016，一路平淡的走过。仔细想想，虽然做了很多项目，也涉猎了几本技术书籍，和一些用到的新技术，但并没有更深入的了解，更没有一个模块化的知识体系。所以是时候给自己定个目标了，让2017年更加充实。   </p>
<ul>
<li><p>Java</p>
<ul>
<li>Java编程思想，目前看了一小半，今年争取把这本神书看完</li>
<li>Effective Java </li>
</ul>
</li>
<li><p>数据结构与算法</p>
<ul>
<li><a href="http://open.163.com/special/opencourse/algorithms.html" target="_blank" rel="external">麻省理工学院公开课：算法导论</a></li>
<li>数据结构与算法-Java语言描述</li>
</ul>
</li>
<li><p>Android </p>
<ul>
<li>将现有知识再进行深度扩展，了解更低层的一些东西。</li>
<li>插件化开发，热更新原理及实践。</li>
<li>坚持看鸿洋和郭霖的技术公众号，积累技术干货。</li>
<li>掌握Android技术新动向</li>
</ul>
</li>
<li><p>其他</p>
<ul>
<li>至少1500个英语单词</li>
<li>看两本以上非技术书籍</li>
<li>GitHub上有一个上百Star的项目</li>
<li>每个月至少两篇技术博客</li>
<li>了解下机器学习人工智能方向的知识，这个可能是以后的热点。 </li>
</ul>
</li>
</ul>
<p>先暂时写这么多吧，一年后看看自己的成果。每做完一件事更新下状态，并标注日期。激励下自己，每天进步一点点。(Ps.地铁上是一段可以很好利用的时间，与其看新闻，不如背单词或者看看技术文章)。</p>
]]></content>
    
    <summary type="html">
    
      &lt;p&gt;2016，一路平淡的走过。仔细想想，虽然做了很多项目，也涉猎了几本技术书籍，和一些用到的新技术，但并没有更深入的了解，更没有一个模块化的知识体系。所以是时候给自己定个目标了，让2017年更加充实。   &lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;&lt;p&gt;Java&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;J
    
    </summary>
    
      <category term="学习笔记" scheme="http://ibat.xyz/categories/%E5%AD%A6%E4%B9%A0%E7%AC%94%E8%AE%B0/"/>
    
    
  </entry>
  
  <entry>
    <title>理解RSA算法</title>
    <link href="http://ibat.xyz/2016/08/23/%E7%90%86%E8%A7%A3RSA%E7%AE%97%E6%B3%95/"/>
    <id>http://ibat.xyz/2016/08/23/理解RSA算法/</id>
    <published>2016-08-23T13:34:21.000Z</published>
    <updated>2019-01-17T02:58:46.860Z</updated>
    
    <content type="html"><![CDATA[<h1 id="理解RSA算法"><a href="#理解RSA算法" class="headerlink" title="理解RSA算法"></a>理解RSA算法</h1><blockquote>
<p>本文是看完阮一峰的”RSA算法原理”后所做的笔记,有兴趣的同学可以移步至:<a href="http://www.ruanyifeng.com/blog/2013/06/rsa_algorithm_part_one.html" target="_blank" rel="external">RSA算法原理–阮一峰</a></p>
<h2 id="一-简介"><a href="#一-简介" class="headerlink" title="一.简介"></a>一.简介</h2><p><strong>非对称加密算法:非对称加密需要两个密钥,公钥和私钥.</strong><br>1.乙方生成两把密钥(公钥和私钥).公钥是公开的,任何人都可以获得,私钥是保密的<br>2.甲方获取乙方的公钥,然后用它对信息加密<br>3.乙方得到加密后的信息,用私钥解密    </p>
</blockquote>
<p>如果公钥加密的信息只有私钥解得开,只要私钥不泄露,通信就是安全的.</p>
<h2 id="二-欧拉函数"><a href="#二-欧拉函数" class="headerlink" title="二.欧拉函数"></a>二.欧拉函数</h2><p><a href="https://zh.wikipedia.org/wiki/%E6%AC%A7%E6%8B%89%E5%87%BD%E6%95%B0" target="_blank" rel="external">欧拉函数</a>,在数论中，对正整数n，欧拉函数φ(n)是小于或等于n的正整数中与n互质的数的数目.例如:φ(8) = 4,因为1,3,5,7均与8互质.  </p>
<p>通式:<br><img src="/img/rsatongshi.jpeg" alt="欧拉函数公式(1)"><br>其中p1,p2….pn为x的所有质因数,x为不为0的整数.注意：<strong>每种质因数只一个</strong>。<br>比如:12 = 2×2×3 那么 φ（12）=12<em>（1-1/2）</em>(1-1/3)=4  </p>
<h3 id="第一种情况"><a href="#第一种情况" class="headerlink" title="第一种情况"></a>第一种情况</h3><p>如果n=1，则 φ(1) = 1 。因为1与任何数（包括自身）都构成互质关系。</p>
<h3 id="第二种情况"><a href="#第二种情况" class="headerlink" title="第二种情况"></a>第二种情况</h3><p>如果n是质数，则 φ(n)=n-1 。因为质数与小于它的每一个数，都构成互质关系。比如5与1、2、3、4都构成互质关系。</p>
<h3 id="第三种情况"><a href="#第三种情况" class="headerlink" title="第三种情况"></a>第三种情况</h3><p>如果n是质数的某一个次方，即 n = p^k (p为质数，k为大于等于1的整数)，则<br><img src="/img/rsa3.jpeg" alt="欧拉函数公式(2)"><br>这是因为只有当一个数不包含质数p，才可能与n互质。而包含质数p的数一共有p^(k-1)个，即1×p、2×p、3×p、…、p^(k-1)×p，把它们去除，剩下的就是与n互质的数。</p>
<h3 id="第四种情况"><a href="#第四种情况" class="headerlink" title="第四种情况"></a>第四种情况</h3><p>如果n可以分解成两个互质的整数之积<br><strong>n = p1 × p2</strong>   则  <strong>φ(n) = φ(p1p2) = φ(p1)φ(p2)</strong></p>
<h2 id="三-欧拉定理"><a href="#三-欧拉定理" class="headerlink" title="三.欧拉定理"></a>三.欧拉定理</h2><p>如果两个正整数a和n互质，则n的欧拉函数 φ(n) 可以让下面的等式成立：<br><img src="/img/ouladingli.jpeg" alt="欧拉定理"><br>也就是说，a的φ(n)次方被n除的余数为1。或者说，a的φ(n)次方减去1，可以被n整除。比如，3和7互质，而7的欧拉函数φ(7)等于6，所以3的6次方（729）减去1，可以被7整除（728/7=104）。<br>欧拉定理有一个特殊情况。<br>假设正整数a与质数p互质，因为质数p的φ(p)等于p-1，则欧拉定理可以写成<br><img src="/img/ouladingli2.jpeg" alt="欧拉定理">  </p>
<h2 id="四-模反元素"><a href="#四-模反元素" class="headerlink" title="四.模反元素"></a>四.模反元素</h2><p>如果两个正整数a和n互质，那么一定可以找到整数b，使得 ab-1 被n整除，或者说ab被n除的余数是1。</p>
<blockquote>
<p>###<strong>ab ≡ 1( mod n )</strong>  </p>
</blockquote>
<p>这时，b就叫做a的”模反元素”。<br>比如，3和11互质，那么3的模反元素就是4，因为 (3 × 4)-1 可以被11整除。显然，模反元素不止一个， 4加减11的整数倍都是3的模反元素 {…,-18,-7,4,15,26,…}，即如果b是a的模反元素，则 b+kn 都是a的模反元素。</p>
<h2 id="五-RSA算法原理"><a href="#五-RSA算法原理" class="headerlink" title="五.RSA算法原理"></a>五.RSA算法原理</h2><h3 id="1-密钥生成步骤"><a href="#1-密钥生成步骤" class="headerlink" title="1.密钥生成步骤"></a>1.密钥生成步骤</h3><p>比如,老张和老王是两名地下工作者,老张要向老王传达一个机密的文件.这时老张想到了RSA算法.<br><strong>(1)  随机选择两个不相等的质数p,q.</strong><br>这时,老张选择了61和53.<br><strong>(2)  计算p和q的乘积n.</strong>  </p>
<pre><code>n = p * q = 61 * 53 = 3233.  
</code></pre><p>n的长度就是密钥长度。3233写成二进制是110010100001，一共有12位，所以这个密钥就是12位。实际应用中，RSA密钥一般是1024位，重要场合则为2048位。<br><strong>(3)  计算n的欧拉函数φ(n).</strong><br>根据上面所介绍的欧拉定理第四种情况:</p>
<pre><code>φ(n) = φ(3233) = φ(61) * φ(53) = 60 * 52 = 3120;  
</code></pre><p><strong>(4)  随机选择一个整数e，条件是1&lt; e &lt; φ(n)，且e与φ(n) 互质.</strong><br>这时,老张从1-3120之间,随机选择了17.（实际应用中，常常选择65537）.<br><strong>(5)  计算e对于φ(n)的模反元素d</strong><br>所谓”模反元素”就是指有一个整数d，可以使得ed被φ(n)除的余数为1。</p>
<pre><code>ed ≡ 1 (mod φ(n))  
</code></pre><p>这个公式等价于 </p>
<pre><code>ed - 1 = kφ(n)
</code></pre><p>于是，找到模反元素d，实质上就是对下面这个二元一次方程求解。</p>
<pre><code>ex - φ(n)y = 1
</code></pre><p>那么,已知e = 17,φ(n) = 3120 ,求x的值 </p>
<pre><code>17x - 3120y = 1  
</code></pre><p>这个方程可以用”扩展欧几里得算法”求解，此处省略具体过程。总之，老张算出一组整数解为 (x,y)=(2753,15)，即 d=2753。<br><strong>(6)  将n和e封装成公钥，n和d封装成私钥</strong><br>n=3233，e=17，d=2753，所以公钥就是 (3233,17)，私钥就是（3233, 2753）,即公钥为( n,e ),私钥为( n,d )。<br>实际应用中，公钥和私钥的数据都采用<a href="https://zh.wikipedia.org/zh-cn/ASN.1" target="_blank" rel="external">ASN.1</a>格式表达。  </p>
<h3 id="2-RSA算法的可靠性"><a href="#2-RSA算法的可靠性" class="headerlink" title="2.RSA算法的可靠性"></a>2.RSA算法的可靠性</h3><p>老张进行了这些计算后,整理了下上面所提到的数字:  </p>
<pre><code>随机选择的两个质数:p 61 , q 53  
质数的乘积:n
n的欧拉函数φ(n):3120
随机选择的整数e:17
e的模反元素d:2753
</code></pre><p>这六个数字之中，公钥用到了两个（n和e），其余四个数字都是不公开的。其中最关键的是d，因为n和d组成了私钥，一旦d泄漏，就等于私钥泄漏。<br><strong>老张想,有没有可能在已知n和e的情况下,也就是知道公钥的情况下,推导出d?</strong>  </p>
<pre><code>（1）ed≡1 (mod φ(n))。只有知道e和φ(n)，才能算出d。
（2）φ(n)=(p-1)(q-1)。只有知道p和q，才能算出φ(n)。
（3）n=pq。只有将n因数分解，才能算出p和q。
</code></pre><p>结论：如果n可以被因数分解，d就可以算出，也就意味着私钥被破解。可是，大整数的因数分解，是一件非常困难的事情.</p>
<blockquote>
<p>　 “对极大整数做因数分解的难度决定了RSA算法的可靠性。换言之，对一极大整数做因数分解愈困难，RSA算法愈可靠。<br>　假如有人找到一种快速因数分解的算法，那么RSA的可靠性就会极度下降。但找到这样的算法的可能性是非常小的。今天只有短的RSA密钥才可能被暴力破解。到2008年为止，世界上还没有任何可靠的攻击RSA算法的方式。<br>　只要密钥长度足够长，用RSA加密的信息实际上是不能被解破的。”</p>
</blockquote>
<h3 id="3-加密和解密"><a href="#3-加密和解密" class="headerlink" title="3.加密和解密"></a>3.加密和解密</h3><p>有了公钥和密钥，就能进行加密和解密了。<br>1.加密要用公钥 (n,e)<br>假设老张要向老王发送加密信息m，他就要用老王的公钥 (n,e) 对m进行加密。这里需要注意，m必须是整数（字符串可以取ascii值或unicode值），且m必须小于n。<br>所谓”加密”，就是算出下式的c：  </p>
<pre><code>me ≡ c (mod n)
</code></pre><p>老王的公钥是 (3233, 17)，老张的m假设是65，那么可以算出下面的等式：</p>
<pre><code>6517 ≡ 2790 (mod 3233)
</code></pre><p>于是，c等于2790，老张就把2790发给了老王。  </p>
<p>2.解密要用私钥(n,d)<br>老王拿到老张发来的2790以后，就用自己的私钥(3233, 2753) 进行解密。可以证明，下面的等式一定成立：（证明过程略，有兴趣可以看阮一峰的博客）  </p>
<pre><code>cd ≡ m (mod n)
</code></pre><p>　　<br>也就是说，c的d次方除以n的余数为m。现在，c等于2790，私钥是(3233, 2753)，那么，老王算出  </p>
<pre><code>27902753 ≡ 65 (mod 3233)
</code></pre><p>因此，老王知道了老张加密前的原文就是65。  </p>
<p>我们可以看到，如果不知道d，就没有办法从c求出m。而前面已经说过，要知道d就必须分解n，这是极难做到的，所以RSA算法保证了通信安全。<br>你可能会问，公钥(n,e) 只能加密小于n的整数m，那么如果要加密大于n的整数，该怎么办？有两种解决方法：一种是把长信息分割成若干段短消息，每段分别加密；另一种是先选择一种”对称性加密算法”（比如DES），用这种算法的密钥加密信息，再用RSA公钥加密DES密钥。</p>
]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;理解RSA算法&quot;&gt;&lt;a href=&quot;#理解RSA算法&quot; class=&quot;headerlink&quot; title=&quot;理解RSA算法&quot;&gt;&lt;/a&gt;理解RSA算法&lt;/h1&gt;&lt;blockquote&gt;
&lt;p&gt;本文是看完阮一峰的”RSA算法原理”后所做的笔记,有兴趣的同学可以移步至:
    
    </summary>
    
      <category term="算法" scheme="http://ibat.xyz/categories/%E7%AE%97%E6%B3%95/"/>
    
    
  </entry>
  
  <entry>
    <title>使用productFlavors配置项目移植</title>
    <link href="http://ibat.xyz/2016/07/16/%E4%BD%BF%E7%94%A8productFlavors%E9%85%8D%E7%BD%AE%E9%A1%B9%E7%9B%AE%E7%A7%BB%E6%A4%8D/"/>
    <id>http://ibat.xyz/2016/07/16/使用productFlavors配置项目移植/</id>
    <published>2016-07-16T14:32:15.000Z</published>
    <updated>2016-11-19T14:33:52.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="使用productFlavors配置项目移植"><a href="#使用productFlavors配置项目移植" class="headerlink" title="使用productFlavors配置项目移植"></a>使用productFlavors配置项目移植</h1><h2 id="概述"><a href="#概述" class="headerlink" title="概述"></a>概述</h2><p>有时候需要做两个或多个项目,但都用的同一套代码.只有稍微的一些布局或者代码的改动.<br>我们常规的做法是再切一个分支,再在这个分支上做相应的改动.但比如发现了某一处bug,或者需要统一改个需求.那我们就需要在每一个分支上都进行这种变动.<br>如果项目多的话会很不好维护.下面就介绍怎样通过productFlavors的方式配置项目移植. </p>
<h2 id="Flavor"><a href="#Flavor" class="headerlink" title="Flavor"></a>Flavor</h2><h3 id="在主项目build-gradle中配置productFlavors"><a href="#在主项目build-gradle中配置productFlavors" class="headerlink" title="在主项目build.gradle中配置productFlavors"></a>在主项目build.gradle中配置productFlavors</h3><pre><code>android{
    ...
    defaultConfig{
    ...
    }
    productFlavors{
        jkxt {
            applicationId &quot;com.****.****&quot;
            buildConfigField &quot;String&quot;, &quot;PROJECT_SIGN&quot;, &quot;\&quot;jkxt\&quot;&quot;
            manifestPlaceholders = [BAIDU_CHANNEL_VALUE       : &quot;*****&quot;,
                                    PACKAGE_NAME              : &quot;*****&quot;]
        }
        jkhd {
            applicationId &quot;com.****.****&quot;
            buildConfigField &quot;String&quot;, &quot;PROJECT_SIGN&quot;, &quot;\&quot;jkhd\&quot;&quot;
            manifestPlaceholders = [BAIDU_CHANNEL_VALUE       : &quot;*****&quot;,
                                    PACKAGE_NAME              : &quot;*****&quot;]
        }
    }
}
</code></pre><p>上面定义了一个productFlavors,gradle会为这个flavor关联对应的sourceSet,默认位置为src/<flavorname>目录,对应到本例就是src/jkhd,如果没有建文件夹,则默认为src/main.看如下解释</flavorname></p>
<blockquote>
<p>#####The product flavors support the same properties as defaultConfig—this is because defaultConfig actually belongs to the ProductFlavor class. This means you can provide the base configuration for all flavors in the defaultConfig {} block, and each flavor can override any of these default values, such as the applicationId.  </p>
</blockquote>
<p>也就是说,defaultConfig中可以配置的属性,比如applicationId,minSdkVersion等,都可以在productFlavors中配置,因为<strong>defaultConfig就是一个productFlavor实例</strong>.</p>
<p>在本例中,解释上面两个属性,<strong>buildConfigField</strong>可以理解为定义一个常量,传入的值分别代表type,name,value;<br>通过BuildConfig.PROJECT_SIGN  可以拿到相应的值,比如我们熟悉的BuildConfig.DEBUG,就是系统定义的一个常量.  </p>
<p><strong>manifestPlaceholders</strong>作用是动态替换manifest文件,传入的是一个map对象,写法如上所示.在配置多个项目时,一些第三方的key比如友盟,极光等需要进行动态配置,就需要用到这个属性,在manifest文件中把需要动态配置的属性按如下写法,android:name=”${PACKAGE_NAME}”</p>
<h2 id="替换资源文件"><a href="#替换资源文件" class="headerlink" title="替换资源文件"></a>替换资源文件</h2><p>上面讲到productFlavors已经为我们关联了对应的sourceSet,所以我们只需要把不同的资源文件放入相应目录下<br>以jkhd为例,在src/jkhd目录下新建res文件,新建需要替换的资源文件夹,比如需要替换app_name<br>只需要在src/jkhd/res/values/string.xml,新建app_name标签即可.<strong>其他公用的资源不需要添加,找不到的话会默认从主项目下面找</strong>.</p>
<h2 id="使用第三方sdk"><a href="#使用第三方sdk" class="headerlink" title="使用第三方sdk"></a>使用第三方sdk</h2><p>做某些项目可能用用到不用的第三方sdk,但其他项目并不需要这个sdk,那么怎么为特定的项目添加sdk呢?   </p>
<pre><code>android {
productFlavors {
    jkhd {
        }
    }
}
...
dependencies {
    jkhdCompile &apos;com.nineoldandroids:library:2.4.0&apos;
}
</code></pre><p>然后通过反射的方法,进行具体判断</p>
<pre><code>class MyActivity extends Activity {
private boolean useSdk;

@override
public void onCreate(Bundle savedInstanceState) {
    try {
        Class.forName(&quot;com.nineoldandroids.......&quot;);
        useSdk = true;
    } catch (ClassNotFoundException ignored) {
        }
    }
}
</code></pre><h2 id="动态替换代码"><a href="#动态替换代码" class="headerlink" title="动态替换代码"></a>动态替换代码</h2><ol>
<li>如果在src/jkhd目录下新建同名类的话会报类重复的问题.但我们可以新建src/jkhd,和src/jkxt两个文件夹,在这两个文件夹中同时写入一个与主目录不同的类,在主目录中进行调用,这样是没有问题的  </li>
<li>直接在主目录中以判断标记位的方法来达到动态替换的效果.  </li>
</ol>
<h2 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h2><p>productFlavors对于配置项目移植,和多渠道打包都非常方便,节省了我们大量的工作.目前所介绍的配置基本上可以满足我们的需求.以后再也不用担心多渠道打包和项目移植啦~  </p>
<p>欢迎大家提出更多新的用法!</p>
<p>参考资料<br><a href="http://tools.android.com/tech-docs/new-build-system/user-guide#TOC-Product-flavors" target="_blank" rel="external">Product-flavors</a><br><a href="http://tech.meituan.com/mt-apk-adaptation.html" target="_blank" rel="external">美团Android自动化之旅—适配渠道包</a></p>
]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;使用productFlavors配置项目移植&quot;&gt;&lt;a href=&quot;#使用productFlavors配置项目移植&quot; class=&quot;headerlink&quot; title=&quot;使用productFlavors配置项目移植&quot;&gt;&lt;/a&gt;使用productFlavors配置项目
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
  </entry>
  
  <entry>
    <title>Android--参考资料</title>
    <link href="http://ibat.xyz/2016/06/28/Android-%E8%B5%84%E6%96%99%E6%95%B4%E7%90%86/"/>
    <id>http://ibat.xyz/2016/06/28/Android-资料整理/</id>
    <published>2016-06-28T13:29:49.000Z</published>
    <updated>2017-06-03T07:00:06.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="博客推荐"><a href="#博客推荐" class="headerlink" title="博客推荐:"></a>博客推荐:</h1><p>这些都是我在学习Android的时候经常会看的一些博客，希望有一天能像这些大神一样牛逼。  </p>
<p>Hongyang:<a><a href="http://zhanghongyang.com" target="_blank" rel="external">http://zhanghongyang.com</a></a><br>郭霖：<a><a href="http://guolin.tech" target="_blank" rel="external">http://guolin.tech</a></a><br>stormzhang:<a><a href="http://stormzhang.com/" target="_blank" rel="external">http://stormzhang.com/</a></a><br>任玉刚:<a><a href="http://blog.csdn.net/singwhatiwanna" target="_blank" rel="external">http://blog.csdn.net/singwhatiwanna</a></a><br>阮一峰:<a><a href="http://ruanyifeng.com" target="_blank" rel="external">http://ruanyifeng.com</a></a><br>codeKK(力推，各种源码解析，开源项目汇总。):<a><a href="http://codekk.com" target="_blank" rel="external">http://codekk.com</a></a><br>Trinea():<a><a href="http://www.trinea.cn/" target="_blank" rel="external">http://www.trinea.cn/</a></a><br>泡在网上的日子:<a><a href="http://www.jcodecraeer.com/" target="_blank" rel="external">http://www.jcodecraeer.com/</a></a>  </p>
<h1 id="知识点备忘"><a href="#知识点备忘" class="headerlink" title="知识点备忘"></a>知识点备忘</h1><p><a href="http://www.jianshu.com/p/7fe9d3bb00ac" target="_blank" rel="external">遗传算法在自动组卷中的应用</a></p>
<p><a href="http://blog.csdn.net/briblue/article/details/54973413" target="_blank" rel="external">java中的ClassLoader详解</a> </p>
<p><a href="http://jaeger.itscoder.com/android/2016/08/27/android-classloader.html" target="_blank" rel="external">热修复入门，Andoroid中的ClassLoader详解</a></p>
<p><a href="http://blog.csdn.net/luoshengyang/article/details/8791064" target="_blank" rel="external">Android应用程序资源管理器（Asset Manager）的创建过程分析</a>  </p>
<p><a href="http://blog.csdn.net/singwhatiwanna/article/details/24532419" target="_blank" rel="external">Android源码分析-资源加载机制</a>    </p>
<p><a href="http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2017/0523/7963.html" target="_blank" rel="external">App开发架构指南（谷歌官方文档译文）</a>  </p>
<p><a href="http://blog.coderclock.com/2017/03/26/android/%E5%85%B3%E4%BA%8EAndroid%20RecyclerView%E7%9A%84%E9%82%A3%E4%BA%9B%E5%BC%80%E6%BA%90LayoutManager/" target="_blank" rel="external">关于Android RecyclerView的那些开源LayoutManager</a>  </p>
<p><a href="http://connorlin.github.io/2016/07/02/Android-Data-Binding-%E7%B3%BB%E5%88%97-%E4%B8%80-%E8%AF%A6%E7%BB%86%E4%BB%8B%E7%BB%8D%E4%B8%8E%E4%BD%BF%E7%94%A8/" target="_blank" rel="external">Android Data Binding 系列</a>  </p>
<p><a href="https://developer.android.com/topic/libraries/data-binding/index.html" target="_blank" rel="external">Android Data Binding文档</a></p>
<h1 id="Kotlin相关"><a href="#Kotlin相关" class="headerlink" title="Kotlin相关"></a>Kotlin相关</h1><p><a href="https://android-developers.googleblog.com/2017/05/android-announces-support-for-kotlin.html" target="_blank" rel="external">Android Announces Support for Kotlin</a><br><a href="https://www.kotlincn.net/docs/reference/" target="_blank" rel="external">Kotlin语言中文站</a><br><a href="https://www.gitbook.com/book/hltj/kotlin-reference-chinese/details" target="_blank" rel="external">Kotlin官方参考文档 中文版</a><br><a href="https://github.com/wangjiegulu/kotlin-for-android-developers-zh/blob/master/README.md" target="_blank" rel="external">《Kotlin for android developers》中文版翻译</a><br><a href="https://kymjs.com/column/kotlin.html" target="_blank" rel="external">张涛-开源实验室</a>  </p>
]]></content>
    
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      &lt;h1 id=&quot;博客推荐&quot;&gt;&lt;a href=&quot;#博客推荐&quot; class=&quot;headerlink&quot; title=&quot;博客推荐:&quot;&gt;&lt;/a&gt;博客推荐:&lt;/h1&gt;&lt;p&gt;这些都是我在学习Android的时候经常会看的一些博客，希望有一天能像这些大神一样牛逼。  &lt;/p&gt;
&lt;p&gt;Hongya
    
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  <entry>
    <title>ViewDragHelper——打造你的专属ViewGroup</title>
    <link href="http://ibat.xyz/2016/05/17/ViewDragHelper%E7%94%A8%E6%B3%95%E4%BB%8B%E7%BB%8D/"/>
    <id>http://ibat.xyz/2016/05/17/ViewDragHelper用法介绍/</id>
    <published>2016-05-17T14:53:10.000Z</published>
    <updated>2016-05-17T15:58:04.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="ViewDragHelper介绍"><a href="#ViewDragHelper介绍" class="headerlink" title="ViewDragHelper介绍"></a>ViewDragHelper介绍</h1><p>转载请注明出处，有问题的话欢迎在下面留言，我会一一回复，谢谢大家。你们的关注是我最大的动力。</p>
<p>在自定义控件中，很多效果都需要重写onInterceptTouchEvent和onTouchEvent这两个类，但要考虑到各种情况，写出很好的手势处理控件是比较麻烦的。比如多点触控，速度监测等。ViewDragHelper是谷歌io大会上隆重推出的手势处理的类。在android.support.v4中。像Google官方侧滑菜单，DrawerLayout就是用这个类实现的。本节先介绍它的基本用法，以后会介绍如何用ViewDragHelper自定义侧滑菜单。</p>
<h1 id="基本实现"><a href="#基本实现" class="headerlink" title="基本实现"></a>基本实现</h1><h2 id="创建实例"><a href="#创建实例" class="headerlink" title="创建实例"></a>创建实例</h2><pre><code>mViewDragHelper = ViewDragHelper.create(this,1.0f,callback);
</code></pre><p>需要传入三个参数，第一个参数传入当前的ViewGroup；第二个参数是灵敏度，数值越大，灵敏度越低；第三个参数传入ViewDragHelper.Callback,后面详细介绍。</p>
<h2 id="触摸相关的方法"><a href="#触摸相关的方法" class="headerlink" title="触摸相关的方法"></a>触摸相关的方法</h2><figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div></pre></td><td class="code"><pre><div class="line"><span class="meta">@Override</span></div><div class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">boolean</span> <span class="title">onInterceptTouchEvent</span><span class="params">(MotionEvent ev)</span> </span>&#123;</div><div class="line">	<span class="comment">// 让ViewDragHelper帮我们判断是否应该拦截</span></div><div class="line">	<span class="keyword">boolean</span> result = viewDragHelper.shouldInterceptTouchEvent(ev);</div><div class="line">	<span class="keyword">return</span> result;</div><div class="line">&#125;</div><div class="line"></div><div class="line"><span class="meta">@Override</span></div><div class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">boolean</span> <span class="title">onTouchEvent</span><span class="params">(MotionEvent event)</span> </span>&#123;</div><div class="line">	<span class="comment">// 将触摸事件交给ViewDragHelper来解析处理</span></div><div class="line">	viewDragHelper.processTouchEvent(event);</div><div class="line">	<span class="keyword">return</span> <span class="keyword">true</span>;</div><div class="line">&#125;</div></pre></td></tr></table></figure>
<h2 id="ViewDragHelper-Callback的相关方法"><a href="#ViewDragHelper-Callback的相关方法" class="headerlink" title="ViewDragHelper.Callback的相关方法"></a><strong>ViewDragHelper.Callback</strong>的相关方法</h2><p>callback的方法，大家参考注释。  </p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div><div class="line">35</div><div class="line">36</div><div class="line">37</div><div class="line">38</div><div class="line">39</div><div class="line">40</div><div class="line">41</div><div class="line">42</div><div class="line">43</div><div class="line">44</div><div class="line">45</div><div class="line">46</div><div class="line">47</div><div class="line">48</div><div class="line">49</div><div class="line">50</div><div class="line">51</div><div class="line">52</div><div class="line">53</div><div class="line">54</div><div class="line">55</div><div class="line">56</div><div class="line">57</div><div class="line">58</div><div class="line">59</div><div class="line">60</div><div class="line">61</div><div class="line">62</div><div class="line">63</div><div class="line">64</div><div class="line">65</div><div class="line">66</div><div class="line">67</div><div class="line">68</div><div class="line">69</div><div class="line">70</div><div class="line">71</div><div class="line">72</div><div class="line">73</div><div class="line">74</div><div 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class="line">113</div><div class="line">114</div><div class="line">115</div><div class="line">116</div><div class="line">117</div><div class="line">118</div><div class="line">119</div><div class="line">120</div><div class="line">121</div><div class="line">122</div><div class="line">123</div><div class="line">124</div><div class="line">125</div><div class="line">126</div><div class="line">127</div><div class="line">128</div><div class="line">129</div><div class="line">130</div><div class="line">131</div><div class="line">132</div><div class="line">133</div><div class="line">134</div><div class="line">135</div><div class="line">136</div><div class="line">137</div><div class="line">138</div><div class="line">139</div><div class="line">140</div><div class="line">141</div><div class="line">142</div><div class="line">143</div><div class="line">144</div></pre></td><td class="code"><pre><div class="line"></div><div class="line"><span class="keyword">private</span> ViewDragHelper.Callback callback = <span class="keyword">new</span> ViewDragHelper.Callback() &#123;</div><div class="line">		<span class="comment">/**</span></div><div class="line">		 * 用于判断是否捕获当前child的触摸事件 child: 当前触摸的子View return: true:就捕获并解析 false：不处理</div><div class="line">		 */</div><div class="line">		<span class="meta">@Override</span></div><div class="line">		<span class="function"><span class="keyword">public</span> <span class="keyword">boolean</span> <span class="title">tryCaptureView</span><span class="params">(View child, <span class="keyword">int</span> pointerId)</span> </span>&#123;</div><div class="line">			<span class="keyword">return</span> child == blueView || child == redView;</div><div class="line">		&#125;</div><div class="line"></div><div class="line">		<span class="comment">/**</span></div><div class="line">		 * 当view被开始捕获和解析的回调 capturedChild:当前被捕获的子view</div><div class="line">		 */</div><div class="line">		<span class="meta">@Override</span></div><div class="line">		<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">onViewCaptured</span><span class="params">(View capturedChild, <span class="keyword">int</span> activePointerId)</span> </span>&#123;</div><div class="line">			<span class="keyword">super</span>.onViewCaptured(capturedChild, activePointerId);</div><div class="line">			<span class="comment">// Log.e("tag", "onViewCaptured");</span></div><div class="line">		&#125;</div><div class="line"></div><div class="line">		<span class="comment">/**</span></div><div class="line">		 * 获取view水平方向的拖拽范围,但是目前不能限制边界,返回的值目前用在手指抬起的时候view缓慢移动的动画世界的计算上面; 最好不要返回0</div><div class="line">		 */</div><div class="line">		<span class="meta">@Override</span></div><div class="line">		<span class="function"><span class="keyword">public</span> <span class="keyword">int</span> <span class="title">getViewHorizontalDragRange</span><span class="params">(View child)</span> </span>&#123;</div><div class="line">			<span class="keyword">return</span> getMeasuredWidth() - child.getMeasuredWidth();</div><div class="line">		&#125;</div><div class="line"></div><div class="line">		<span class="comment">/**</span></div><div class="line">		 * 获取view垂直方向的拖拽范围，最好不要返回0</div><div class="line">		 */</div><div class="line">		<span class="function"><span class="keyword">public</span> <span class="keyword">int</span> <span class="title">getViewVerticalDragRange</span><span class="params">(View child)</span> </span>&#123;</div><div class="line">			<span class="keyword">return</span> getMeasuredHeight() - child.getMeasuredHeight();</div><div class="line">		&#125;</div><div class="line"></div><div class="line">		<span class="comment">/**</span></div><div class="line">		 * 控制child在水平方向的移动 left:</div><div class="line">		 * 表示ViewDragHelper认为你想让当前child的left改变的值,left=chile.getLeft()+dx dx:</div><div class="line">		 * 本次child水平方向移动的距离 return: 表示你真正想让child的left变成的值</div><div class="line">		 */</div><div class="line">		<span class="meta">@Override</span></div><div class="line">		<span class="function"><span class="keyword">public</span> <span class="keyword">int</span> <span class="title">clampViewPositionHorizontal</span><span class="params">(View child, <span class="keyword">int</span> left, <span class="keyword">int</span> dx)</span> </span>&#123;</div><div class="line">			<span class="keyword">if</span> (left &lt; <span class="number">0</span>) &#123;</div><div class="line">				<span class="comment">// 限制左边界</span></div><div class="line">				left = <span class="number">0</span>;</div><div class="line">			&#125; <span class="keyword">else</span> <span class="keyword">if</span> (left &gt; (getMeasuredWidth() - child.getMeasuredWidth())) &#123;</div><div class="line">				<span class="comment">// 限制右边界</span></div><div class="line">				left = getMeasuredWidth() - child.getMeasuredWidth();</div><div class="line">			&#125;</div><div class="line">			<span class="keyword">return</span> left;</div><div class="line">		&#125;</div><div class="line"></div><div class="line">		<span class="comment">/**</span></div><div class="line">		 * 控制child在垂直方向的移动 top:</div><div class="line">		 * 表示ViewDragHelper认为你想让当前child的top改变的值,top=chile.getTop()+dy dy:</div><div class="line">		 * 本次child垂直方向移动的距离 return: 表示你真正想让child的top变成的值</div><div class="line">		 */</div><div class="line">		<span class="function"><span class="keyword">public</span> <span class="keyword">int</span> <span class="title">clampViewPositionVertical</span><span class="params">(View child, <span class="keyword">int</span> top, <span class="keyword">int</span> dy)</span> </span>&#123;</div><div class="line">			<span class="keyword">if</span> (top &lt; <span class="number">0</span>) &#123;</div><div class="line">				top = <span class="number">0</span>;</div><div class="line">			&#125; <span class="keyword">else</span> <span class="keyword">if</span> (top &gt; getMeasuredHeight() - child.getMeasuredHeight()) &#123;</div><div class="line">				top = getMeasuredHeight() - child.getMeasuredHeight();</div><div class="line">			&#125;</div><div class="line">			<span class="keyword">return</span> top;</div><div class="line">		&#125;;</div><div class="line"></div><div class="line">		<span class="comment">/**</span></div><div class="line">		 * 当child的位置改变的时候执行,一般用来做其他子View的伴随移动 changedView：位置改变的child</div><div class="line">		 * left：child当前最新的left top: child当前最新的top dx: 本次水平移动的距离 dy: 本次垂直移动的距离</div><div class="line">		 */</div><div class="line">		<span class="meta">@Override</span></div><div class="line">		<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">onViewPositionChanged</span><span class="params">(View changedView, <span class="keyword">int</span> left, <span class="keyword">int</span> top,</span></span></div><div class="line">				<span class="keyword">int</span> dx, <span class="keyword">int</span> dy) &#123;</div><div class="line">			<span class="keyword">super</span>.onViewPositionChanged(changedView, left, top, dx, dy);</div><div class="line">			<span class="keyword">if</span> (changedView == blueView) &#123;</div><div class="line">				<span class="comment">// blueView移动的时候需要让redView跟随移动</span></div><div class="line">				redView.layout(redView.getLeft() + dx, redView.getTop() + dy,</div><div class="line">						redView.getRight() + dx, redView.getBottom() + dy);</div><div class="line">			&#125; <span class="keyword">else</span> <span class="keyword">if</span> (changedView == redView) &#123;</div><div class="line">				<span class="comment">// redView移动的时候需要让blueView跟随移动</span></div><div class="line">				blueView.layout(blueView.getLeft() + dx,</div><div class="line">						blueView.getTop() + dy, blueView.getRight() + dx,</div><div class="line">						blueView.getBottom() + dy);</div><div class="line">			&#125;</div><div class="line">			</div><div class="line">			<span class="comment">//1.计算view移动的百分比</span></div><div class="line">			<span class="keyword">float</span> fraction = changedView.getLeft()*<span class="number">1f</span>/(getMeasuredWidth()-changedView.getMeasuredWidth());</div><div class="line">			Log.e(<span class="string">"tag"</span>, <span class="string">"fraction:"</span>+fraction);</div><div class="line">			<span class="comment">//2.执行一系列的伴随动画</span></div><div class="line">			executeAnim(fraction);</div><div class="line">		&#125;</div><div class="line"></div><div class="line">		<span class="comment">/**</span></div><div class="line">		 * 手指抬起的执行该方法， releasedChild：当前抬起的view xvel: x方向的移动的速度 正：向右移动， 负：向左移动</div><div class="line">		 * yvel: y方向移动的速度</div><div class="line">		 */</div><div class="line">		<span class="meta">@Override</span></div><div class="line">		<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">onViewReleased</span><span class="params">(View releasedChild, <span class="keyword">float</span> xvel, <span class="keyword">float</span> yvel)</span> </span>&#123;</div><div class="line">			<span class="keyword">super</span>.onViewReleased(releasedChild, xvel, yvel);</div><div class="line">			<span class="keyword">int</span> centerLeft = getMeasuredWidth() / <span class="number">2</span></div><div class="line">					- releasedChild.getMeasuredWidth() / <span class="number">2</span>;</div><div class="line">			<span class="keyword">if</span> (releasedChild.getLeft() &lt; centerLeft) &#123;</div><div class="line">				<span class="comment">// 在左半边，应该向左缓慢移动</span></div><div class="line">				viewDragHelper.smoothSlideViewTo(releasedChild, <span class="number">0</span>,</div><div class="line">						releasedChild.getTop());</div><div class="line">				ViewCompat.postInvalidateOnAnimation(DragLayout.<span class="keyword">this</span>);</div><div class="line">			&#125; <span class="keyword">else</span> &#123;</div><div class="line">				<span class="comment">// 在右半边，应该向右缓慢移动</span></div><div class="line">				viewDragHelper.smoothSlideViewTo(releasedChild,</div><div class="line">						getMeasuredWidth() - releasedChild.getMeasuredWidth(),</div><div class="line">						releasedChild.getTop());</div><div class="line">				ViewCompat.postInvalidateOnAnimation(DragLayout.<span class="keyword">this</span>);</div><div class="line">			&#125;</div><div class="line">		&#125;</div><div class="line">	&#125;;</div><div class="line">	</div><div class="line"><span class="comment">/**</span></div><div class="line">	 * 执行伴随动画</div><div class="line">	 * <span class="doctag">@param</span> fraction</div><div class="line">	 */</div><div class="line">	<span class="function"><span class="keyword">private</span> <span class="keyword">void</span> <span class="title">executeAnim</span><span class="params">(<span class="keyword">float</span> fraction)</span></span>&#123;</div><div class="line">		<span class="comment">//fraction: 0 - 1</span></div><div class="line">		<span class="comment">//缩放</span></div><div class="line"><span class="comment">//		ViewHelper.setScaleX(redView, 1+0.5f*fraction);</span></div><div class="line"><span class="comment">//		ViewHelper.setScaleY(redView, 1+0.5f*fraction);</span></div><div class="line">		<span class="comment">//旋转</span></div><div class="line"><span class="comment">//		ViewHelper.setRotation(redView,360*fraction);//围绕z轴转</span></div><div class="line">		ViewHelper.setRotationX(redView,<span class="number">360</span>*fraction);<span class="comment">//围绕x轴转</span></div><div class="line"><span class="comment">//		ViewHelper.setRotationY(redView,360*fraction);//围绕y轴转</span></div><div class="line">		ViewHelper.setRotationX(blueView,<span class="number">360</span>*fraction);<span class="comment">//围绕z轴转</span></div><div class="line">		<span class="comment">//平移</span></div><div class="line"><span class="comment">//		ViewHelper.setTranslationX(redView,80*fraction);</span></div><div class="line">		<span class="comment">//透明</span></div><div class="line"><span class="comment">//		ViewHelper.setAlpha(redView, 1-fraction);</span></div><div class="line">		</div><div class="line">		<span class="comment">//设置过度颜色的渐变</span></div><div class="line">		redView.setBackgroundColor((Integer) ColorUtil.evaluateColor(fraction,Color.RED,Color.GREEN));</div><div class="line"><span class="comment">//		setBackgroundColor((Integer) ColorUtil.evaluateColor(fraction,Color.RED,Color.GREEN));</span></div><div class="line">	&#125;</div><div class="line"></div><div class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">computeScroll</span><span class="params">()</span> </span>&#123;</div><div class="line">		<span class="keyword">if</span> (viewDragHelper.continueSettling(<span class="keyword">true</span>)) &#123;</div><div class="line">			ViewCompat.postInvalidateOnAnimation(DragLayout.<span class="keyword">this</span>);</div><div class="line">		&#125;</div><div class="line">	&#125;</div></pre></td></tr></table></figure>
<h2 id="其他代码"><a href="#其他代码" class="headerlink" title="其他代码"></a>其他代码</h2><figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div><div class="line">35</div><div class="line">36</div></pre></td><td class="code"><pre><div class="line"></div><div class="line"><span class="comment">/**</span></div><div class="line"> * 当DragLayout的xml布局的结束标签被读取完成会执行该方法，此时会知道自己有几个子View了 一般用来初始化子View的引用</div><div class="line"> */</div><div class="line"><span class="meta">@Override</span></div><div class="line"><span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">onFinishInflate</span><span class="params">()</span> </span>&#123;</div><div class="line">	<span class="keyword">super</span>.onFinishInflate();</div><div class="line">	redView = getChildAt(<span class="number">0</span>);</div><div class="line">	blueView = getChildAt(<span class="number">1</span>);</div><div class="line">&#125;</div><div class="line"></div><div class="line"> <span class="meta">@Override</span></div><div class="line"> <span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">onMeasure</span><span class="params">(<span class="keyword">int</span> widthMeasureSpec, <span class="keyword">int</span> heightMeasureSpec)</span> </span>&#123;</div><div class="line"> <span class="keyword">super</span>.onMeasure(widthMeasureSpec, heightMeasureSpec);</div><div class="line"> <span class="comment">//要测量我自己的子View</span></div><div class="line"> <span class="comment">// int size = getResources().getDimension(R.dimen.width);//100dp</span></div><div class="line"> <span class="comment">// int measureSpec =</span></div><div class="line"> MeasureSpec.makeMeasureSpec(redView.getLayoutParams().width,MeasureSpec.EXACTLY);</div><div class="line"> <span class="comment">// redView.measure(measureSpec,measureSpec);</span></div><div class="line"> <span class="comment">// blueView.measure(measureSpec, measureSpec);</span></div><div class="line"></div><div class="line"> <span class="comment">//如果说没有特殊的对子View的测量需求，可以用如下方法</span></div><div class="line"> measureChild(redView, widthMeasureSpec, heightMeasureSpec);</div><div class="line"> measureChild(blueView, widthMeasureSpec, heightMeasureSpec);</div><div class="line"> &#125;</div><div class="line"></div><div class="line"><span class="meta">@Override</span></div><div class="line"><span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">onLayout</span><span class="params">(<span class="keyword">boolean</span> changed, <span class="keyword">int</span> l, <span class="keyword">int</span> t, <span class="keyword">int</span> r, <span class="keyword">int</span> b)</span> </span>&#123;</div><div class="line">	<span class="keyword">int</span> left = getPaddingLeft();</div><div class="line">	<span class="keyword">int</span> top = getPaddingTop();</div><div class="line">	redView.layout(left, top, left + redView.getMeasuredWidth(), top</div><div class="line">			+ redView.getMeasuredHeight());</div><div class="line">	blueView.layout(left, redView.getBottom(),</div><div class="line">			left + blueView.getMeasuredWidth(), redView.getBottom()</div><div class="line">					+ blueView.getMeasuredHeight());</div><div class="line">&#125;</div></pre></td></tr></table></figure>
<h2 id="布局文件"><a href="#布局文件" class="headerlink" title="布局文件"></a>布局文件</h2><figure class="highlight xml"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div></pre></td><td class="code"><pre><div class="line"></div><div class="line"><span class="tag">&lt;<span class="name">xyz.ibat.circleview.test.DragLayout</span></span></div><div class="line">        <span class="attr">android:layout_width</span>=<span class="string">"match_parent"</span></div><div class="line">        <span class="attr">android:layout_height</span>=<span class="string">"match_parent"</span> &gt;</div><div class="line"></div><div class="line">        <span class="tag">&lt;<span class="name">TextView</span></span></div><div class="line">            <span class="attr">android:layout_width</span>=<span class="string">"@dimen/width"</span></div><div class="line">            <span class="attr">android:layout_height</span>=<span class="string">"@dimen/width"</span></div><div class="line">            <span class="attr">android:background</span>=<span class="string">"#ff0000"</span> /&gt;</div><div class="line">        <span class="tag">&lt;<span class="name">TextView</span></span></div><div class="line">            <span class="attr">android:layout_width</span>=<span class="string">"@dimen/width"</span></div><div class="line">            <span class="attr">android:layout_height</span>=<span class="string">"@dimen/width"</span></div><div class="line">            <span class="attr">android:background</span>=<span class="string">"#0000ff"</span> /&gt;</div><div class="line">        </div><div class="line">    <span class="tag">&lt;/<span class="name">xyz.ibat.circleview.test.DragLayout</span>&gt;</span></div></pre></td></tr></table></figure>
<p>OK~~源码里注释写的很详细，就不过多描述了。开始打造属于你的ViewGroup吧！</p>
]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;ViewDragHelper介绍&quot;&gt;&lt;a href=&quot;#ViewDragHelper介绍&quot; class=&quot;headerlink&quot; title=&quot;ViewDragHelper介绍&quot;&gt;&lt;/a&gt;ViewDragHelper介绍&lt;/h1&gt;&lt;p&gt;转载请注明出处，有问题的话欢
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
  </entry>
  
  <entry>
    <title>Material Design控件介绍（二）——TabLayout</title>
    <link href="http://ibat.xyz/2016/05/11/Material%20Design%E6%8E%A7%E4%BB%B6%E4%BB%8B%E7%BB%8D(%E4%BA%8C)/"/>
    <id>http://ibat.xyz/2016/05/11/Material Design控件介绍(二)/</id>
    <published>2016-05-11T13:18:37.000Z</published>
    <updated>2016-06-28T13:27:54.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="Material-Design控件介绍（二）——TabLayout"><a href="#Material-Design控件介绍（二）——TabLayout" class="headerlink" title="Material Design控件介绍（二）——TabLayout"></a>Material Design控件介绍（二）——TabLayout</h1><p>项目地址：<a href="https://github.com/JrDong/Android-Sloth" target="_blank" rel="external">https://github.com/JrDong/Android-Sloth</a></p>
<h2 id="TabLayout的用法"><a href="#TabLayout的用法" class="headerlink" title="TabLayout的用法"></a>TabLayout的用法</h2><p>上一篇，我们讲解了Toolbar,DrawerLayout,NavigationView的用法，现在我们来讲解下TabLayout的用法。<br>相信大家都用过ViewPagerIndicator,ViewPager的指示器，TabLayout就是google为我们提供的原生的ViewPager指示器。使用需要在gradle文件中引入</p>
<pre><code>compile &apos;com.android.support:design:23.1.1&apos;
</code></pre><h3 id="布局文件"><a href="#布局文件" class="headerlink" title="布局文件"></a>布局文件</h3><pre><code>&lt;LinearLayout 
    xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
    android:layout_width=&quot;match_parent&quot;
    android:layout_height=&quot;match_parent&quot;
    xmlns:app=&quot;http://schemas.android.com/apk/res-auto&quot;
    android:orientation=&quot;vertical&quot;&gt;

    &lt;android.support.design.widget.TabLayout
        android:id=&quot;@+id/tabs&quot;
        android:layout_width=&quot;match_parent&quot;
        android:layout_height=&quot;wrap_content&quot;
        android:background=&quot;?attr/colorPrimary&quot;
        app:tabGravity=&quot;fill&quot;
        app:tabMode=&quot;fixed&quot; /&gt;

    &lt;android.support.v4.view.ViewPager
        android:id=&quot;@+id/vp_main&quot;
        android:layout_width=&quot;match_parent&quot;
        android:layout_height=&quot;wrap_content&quot;
        android:background=&quot;@color/white&quot; /&gt;
&lt;/LinearLayout&gt;
</code></pre><p>这里有两个比较重要的属性，app:tabGravity 和 app:tabMode</p>
<h4 id="tabGravity"><a href="#tabGravity" class="headerlink" title="tabGravity"></a>tabGravity</h4><p>这个属性有两个值，fill和center，fill指填充满横屏，也就是均分.center指tab居中现实，如下图。<br><img src="/img/tablayout1.png" alt="Alt text"></p>
<h4 id="tabMode"><a href="#tabMode" class="headerlink" title="tabMode"></a>tabMode</h4><p>这个属性也有两个值，scrollable和fixed。比如说你的app tab比较多的话推荐使用scrollable，设置了这个属性后，Tab页可以左右滑动。但fixed还是占满原屏并平分。</p>
<h3 id="代码实现"><a href="#代码实现" class="headerlink" title="代码实现"></a>代码实现</h3><p>现在我们来看下怎么和viewpager结合使用，废话不多说，直接上代码~  </p>
<figure class="highlight aspectj"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div><div class="line">35</div><div class="line">36</div><div class="line">37</div><div class="line">38</div><div class="line">39</div><div class="line">40</div><div class="line">41</div><div class="line">42</div><div class="line">43</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">private</span> <span class="function"><span class="keyword">void</span> <span class="title">initViewPager</span><span class="params">()</span> </span>&#123;</div><div class="line">        ViewPagerAdapter adapter = <span class="keyword">new</span> ViewPagerAdapter((getActivity()).getSupportFragmentManager());</div><div class="line">        adapter.addFragment(<span class="keyword">new</span> OneFragment(), <span class="string">"ONE"</span>);</div><div class="line">        adapter.addFragment(<span class="keyword">new</span> TwoFragment(), <span class="string">"TWO"</span>);</div><div class="line">        adapter.addFragment(<span class="keyword">new</span> ThreeFragment(), <span class="string">"THREE"</span>);</div><div class="line">        mViewPager.setAdapter(adapter);</div><div class="line">        <span class="comment">//必须在setAdapter之后调用</span></div><div class="line">        mTabs.setupWithViewPager(mViewPager);</div><div class="line">        <span class="comment">//设置指示器颜色</span></div><div class="line">        mTabs.setSelectedTabIndicatorColor(getResources().getColor(R.color.white));</div><div class="line">        <span class="comment">//tab的颜色,属性一,正常颜色;属性二,被选中的颜色.</span></div><div class="line">        mTabs.setTabTextColors(getResources().getColor(R.color.white_66), getResources().getColor(R.color.white));</div><div class="line">    &#125;</div><div class="line"></div><div class="line">    <span class="class"><span class="keyword">class</span> <span class="title">ViewPagerAdapter</span> <span class="keyword">extends</span> <span class="title">FragmentPagerAdapter</span> </span>&#123;</div><div class="line">        <span class="keyword">private</span> <span class="keyword">final</span> List&lt;Fragment&gt; mFragmentList = <span class="keyword">new</span> ArrayList&lt;&gt;();</div><div class="line">        <span class="keyword">private</span> <span class="keyword">final</span> List&lt;String&gt; mFragmentTitleList = <span class="keyword">new</span> ArrayList&lt;&gt;();</div><div class="line"></div><div class="line">        <span class="function"><span class="keyword">public</span> <span class="title">ViewPagerAdapter</span><span class="params">(FragmentManager manager)</span> </span>&#123;</div><div class="line">            <span class="keyword">super</span>(manager);</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        <span class="keyword">public</span> <span class="function"><span class="keyword">void</span> <span class="title">addFragment</span><span class="params">(Fragment fragment, String title)</span> </span>&#123;</div><div class="line">            mFragmentList.add(fragment);</div><div class="line">            mFragmentTitleList.add(title);</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        <span class="meta">@Override</span></div><div class="line">        <span class="keyword">public</span> <span class="function">Fragment <span class="title">getItem</span><span class="params">(<span class="keyword">int</span> position)</span> </span>&#123;</div><div class="line">            <span class="function"><span class="keyword">return</span> mFragmentList.<span class="title">get</span><span class="params">(position)</span></span>;</div><div class="line">        &#125;</div><div class="line"></div><div class="line">        <span class="meta">@Override</span></div><div class="line">        <span class="keyword">public</span> <span class="function"><span class="keyword">int</span> <span class="title">getCount</span><span class="params">()</span> </span>&#123;</div><div class="line">            <span class="function"><span class="keyword">return</span> mFragmentList.<span class="title">size</span><span class="params">()</span></span>;</div><div class="line">        &#125;</div><div class="line"></div><div class="line"></div><div class="line">        <span class="meta">@Override</span></div><div class="line">        <span class="keyword">public</span> <span class="function">CharSequence <span class="title">getPageTitle</span><span class="params">(<span class="keyword">int</span> position)</span> </span>&#123;</div><div class="line">            <span class="function"><span class="keyword">return</span> mFragmentTitleList.<span class="title">get</span><span class="params">(position)</span></span>;</div><div class="line">        &#125;</div><div class="line">    &#125;</div></pre></td></tr></table></figure>
<p>注意一点，mTabs.setupWithViewPager(mViewPager);必须在setAdapter之后调用,看下源码:</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div></pre></td><td class="code"><pre><div class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">setupWithViewPager</span><span class="params">(ViewPager viewPager)</span> </span>&#123;</div><div class="line">   	PagerAdapter adapter = viewPager.getAdapter();</div><div class="line">   	<span class="keyword">if</span>(adapter == <span class="keyword">null</span>) &#123;</div><div class="line">      	 <span class="keyword">throw</span> <span class="keyword">new</span> IllegalArgumentException(<span class="string">"ViewPager does not have a PagerAdapter set"</span>);</div><div class="line">   	&#125; <span class="keyword">else</span> &#123;</div><div class="line">       ...</div><div class="line">   	&#125;</div><div class="line">&#125;</div></pre></td></tr></table></figure>
<h3 id="其他要点"><a href="#其他要点" class="headerlink" title="其他要点"></a>其他要点</h3><h4 id="单独设置tab"><a href="#单独设置tab" class="headerlink" title="单独设置tab"></a>单独设置tab</h4><pre><code>TabLayout tabLayout = ...;
 tabLayout.addTab(tabLayout.newTab().setText(&quot;Tab 1&quot;));
tabLayout.addTab(tabLayout.newTab().setText(&quot;Tab 2&quot;));
tabLayout.addTab(tabLayout.newTab().setText(&quot;Tab 3&quot;));
</code></pre><h4 id="设置icon"><a href="#设置icon" class="headerlink" title="设置icon"></a>设置icon</h4>]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;Material-Design控件介绍（二）——TabLayout&quot;&gt;&lt;a href=&quot;#Material-Design控件介绍（二）——TabLayout&quot; class=&quot;headerlink&quot; title=&quot;Material Design控件介绍（二）——Ta
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
  </entry>
  
  <entry>
    <title>Material Design控件介绍（一）——Toolbar,DrawerLayout,NavigationView</title>
    <link href="http://ibat.xyz/2016/04/19/Material%20Design%E6%8E%A7%E4%BB%B6%E4%BB%8B%E7%BB%8D(%E4%B8%80)/"/>
    <id>http://ibat.xyz/2016/04/19/Material Design控件介绍(一)/</id>
    <published>2016-04-19T13:46:05.000Z</published>
    <updated>2016-06-28T13:27:33.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="Material-Design控件介绍（一）———Toolbar-DrawerLayout-NavigationView"><a href="#Material-Design控件介绍（一）———Toolbar-DrawerLayout-NavigationView" class="headerlink" title="Material Design控件介绍（一）———Toolbar,DrawerLayout,NavigationView"></a>Material Design控件介绍（一）———Toolbar,DrawerLayout,NavigationView</h1><p>项目地址:<a href="https://github.com/JrDong/Android-Sloth" target="_blank" rel="external">https://github.com/JrDong/Android-Sloth</a></p>
<h2 id="概述"><a href="#概述" class="headerlink" title="概述"></a>概述</h2><h3 id="介绍的控件有："><a href="#介绍的控件有：" class="headerlink" title="介绍的控件有："></a>介绍的控件有：</h3><p>Toolbar,TabLayout,DrawerLayout,NavigationView<br>CoordinatorLayout,AppBarLayout,CollapsingToolbarLayout<br>NestedScrollView,CardView,FloatingActionButton,Snackbar等<br>还有自定义CoordinatorLayout.Behavior。</p>
<p>先看下效果：<br><img src="/img/Android-Sloth-gif.gif" alt="Alt text"><br>本次先介绍Toolbar，DrawerLayout和NavigationView</p>
<h2 id="Toolbar的用法"><a href="#Toolbar的用法" class="headerlink" title="Toolbar的用法"></a>Toolbar的用法</h2><p>之前大家都接触过ActionBar，继ActionBar之后。Google又推出了一个更加灵活的控件——Toolbar.为什么说Toolbar更加灵活呢，点开Toolbar的源码，我们发现，Toolbar继承自ViewGroup。也就是说，我们可以以Toolbar为父控件，随意的摆放我们需要的控件，并自定义控件的位置。但也可以不这样麻烦，Toolbar也提供了一系列的方法，供我们使用。注意，使用Toolbar需要在AppCompatActivity中，并使用NoActionBar的主题。  </p>
<h3 id="1-首先我们来看下布局文件"><a href="#1-首先我们来看下布局文件" class="headerlink" title="1.首先我们来看下布局文件"></a>1.首先我们来看下布局文件</h3><pre><code>&lt;android.support.v7.widget.Toolbar
xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
xmlns:app=&quot;http://schemas.android.com/apk/res-auto&quot;
android:id=&quot;@+id/main_toolbar&quot;
android:layout_width=&quot;match_parent&quot;
android:layout_height=&quot;wrap_content&quot;
android:minHeight=&quot;?attr/actionBarSize&quot;
android:fitsSystemWindows=&quot;true&quot;
android:theme=&quot;@style/ThemeOverlay.AppCompat.Dark.ActionBar&quot;
app:popupTheme=&quot;@style/ThemeOverlay.AppCompat.Light&quot;
android:background=&quot;?attr/colorPrimary&quot;&gt;
</code></pre><p>Theme表示Toolbar的主题样式，popupTheme表示弹出框的样式。需要改变颜色的话，需要自定义theme，这里先不做介绍。<br>fitsSystemWindows这个属性，是我们使用透明状态栏时用的。当我们使用透明状态栏时。我们应用的标题栏会顶上去，占据原来系统状态栏的位置。这个属性就是用来让view可以根据系统窗口(如status bar)来调整自己的布局，如果值为true,就会调整view的paingding属性来给system windows留出空间….需要在标题栏的父控件中使用。 </p>
<h3 id="2-布局了解-图片来源于网络"><a href="#2-布局了解-图片来源于网络" class="headerlink" title="2.布局了解(图片来源于网络)"></a>2.布局了解(图片来源于网络)</h3><figure class="image-bubble">
                <div class="img-lightbox">
                    <div class="overlay"></div>
                    <img src="/img/1416285884351.png" alt="Alt text" title="">
                </div>
                <div class="image-caption">Alt text</div>
            </figure>
<h3 id="3-代码实现"><a href="#3-代码实现" class="headerlink" title="3.代码实现"></a>3.代码实现</h3><p>添加以下代码就可以使用Toolbar<br>    setSupportActionBar(mainToolbar);<br>setNavigationIcon：比如返回按钮等<br>setLogo:设置应用图标<br>setTitle:主标题<br>setSubTitle:副标题<br>setOnMenuItemClickListener:菜单按钮的点击事件。  </p>
<h3 id="4-菜单栏用法"><a href="#4-菜单栏用法" class="headerlink" title="4.菜单栏用法"></a>4.菜单栏用法</h3><h4 id="在res-menu-menu-main-xml中定义"><a href="#在res-menu-menu-main-xml中定义" class="headerlink" title="在res/menu/menu_main.xml中定义"></a>在res/menu/menu_main.xml中定义</h4><pre><code>&lt;menu xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
  xmlns:app=&quot;http://schemas.android.com/apk/res-auto&quot;
  xmlns:tools=&quot;http://schemas.android.com/tools&quot;
  tools:context=&quot;.MainActivity&quot;&gt;
&lt;item android:id=&quot;@+id/action_settings&quot;
      android:title=&quot;@string/action_settings&quot;
      android:orderInCategory=&quot;100&quot;
      app:showAsAction=&quot;never&quot;/&gt;
&lt;item android:id=&quot;@+id/action_about&quot;
    android:title=&quot;@string/action_about&quot;
    android:orderInCategory=&quot;100&quot;
    app:showAsAction=&quot;never&quot;/&gt;
&lt;item android:id=&quot;@+id/action_search&quot;
    android:title=&quot;@string/action_search&quot;
    android:orderInCategory=&quot;100&quot;
    android:icon=&quot;@mipmap/icon_search&quot;
    app:showAsAction=&quot;ifRoom&quot;
    /&gt;
&lt;/menu&gt;
</code></pre><p>这里需要介绍showAsAction中常用的属性：never表示始终在菜单栏中；ifRoom表示如果标题栏有空闲则在标题栏上显示，没有空闲就在菜单栏中显示；always表示无论有没有空余控件，始终显示在标题栏。不过不推荐使用always，推荐使用ifRoom。  </p>
<pre><code>@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}
</code></pre><h4 id="设置点击事件"><a href="#设置点击事件" class="headerlink" title="设置点击事件"></a>设置点击事件</h4><pre><code>mainToolbar.setOnMenuItemClickListener(new Toolbar.OnMenuItemClickListener() {
        @Override
        public boolean onMenuItemClick(MenuItem item) {
            String msg = &quot;&quot;;
            switch (item.getItemId()){
                case R.id.action_search:
                    msg = &quot;search&quot;;
                    break;
                case R.id.action_about:
                    msg = &quot;about&quot;;
                    break;
                case R.id.action_settings:
                    msg = &quot;setting&quot;;
                    break;
            }
            SlothUtil.showToast(msg);
            return false;
        }
    });
</code></pre><p>至此Toolbar介绍完毕，有需要再继续做补充</p>
<h2 id="DrawerLayout，NavigationView的用法"><a href="#DrawerLayout，NavigationView的用法" class="headerlink" title="DrawerLayout，NavigationView的用法"></a>DrawerLayout，NavigationView的用法</h2><p>DrawerLayout是Google官方的侧滑菜单栏，要使用需要引入v4包，看源码我们发现DrawerLayout其实使用了ViewDragHelper这个类来进行手势处理（有时间会讲解这个类，自定义侧滑菜单）。之前我们使用DrawerLayout，菜单栏喜欢用ListView实现。但有了NavigationView之后，就方便许多。省去了写Adapter的时间。下面就两个结合起来讲解。</p>
<h3 id="首先我们来看下布局文件："><a href="#首先我们来看下布局文件：" class="headerlink" title="首先我们来看下布局文件："></a>首先我们来看下布局文件：</h3><pre><code>&lt;android.support.v4.widget.DrawerLayout
    android:id=&quot;@+id/drawerLayout&quot;
    android:layout_width=&quot;match_parent&quot;
    android:layout_height=&quot;match_parent&quot;&gt;


    &lt;FrameLayout
        android:id=&quot;@+id/fl_root&quot;
        android:layout_width=&quot;match_parent&quot;
        android:layout_height=&quot;match_parent&quot;
        /&gt;


    &lt;android.support.design.widget.NavigationView
        android:id=&quot;@+id/navigation_main&quot;
        android:layout_width=&quot;match_parent&quot;
        android:layout_height=&quot;match_parent&quot;
        android:layout_gravity=&quot;left&quot;
        app:headerLayout=&quot;@layout/navigationview_header&quot;
        app:menu=&quot;@menu/menu_drawer&quot; /&gt;

&lt;/android.support.v4.widget.DrawerLayout&gt;
</code></pre><p>在布局的最外层是DrawerLayout，内容使用FrameLayout，Drawer使用NavigationView<br>细心的同学可能会发现NavigationView多了两个属性。 app:headerLayout=”@layout/navigationview_header”，app:menu=”@menu/menu_drawer” 。这两个属性分别代表，菜单栏的头布局和菜单布局。我们来看下这两个属性中的内容：</p>
<h4 id="1-headerLayout"><a href="#1-headerLayout" class="headerlink" title="1.headerLayout"></a>1.headerLayout</h4><pre><code>&lt;RelativeLayout xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
    android:layout_width=&quot;match_parent&quot;
    android:layout_height=&quot;192dp&quot;
    android:background=&quot;@mipmap/banner2&quot;
    android:fitsSystemWindows=&quot;true&quot;
    android:orientation=&quot;vertical&quot;
    android:padding=&quot;16dp&quot;
    android:theme=&quot;@style/ThemeOverlay.AppCompat.Dark&quot;&gt;

&lt;TextView
    android:id=&quot;@+id/id_link&quot;
    android:layout_width=&quot;wrap_content&quot;
    android:layout_height=&quot;wrap_content&quot;
    android:layout_alignParentBottom=&quot;true&quot;
    android:layout_marginBottom=&quot;16dp&quot;
    android:text=&quot;http://ibat.xyz&quot; /&gt;

&lt;TextView
    android:id=&quot;@+id/id_username&quot;
    android:layout_width=&quot;wrap_content&quot;
    android:layout_height=&quot;wrap_content&quot;
    android:layout_above=&quot;@id/id_link&quot;
    android:text=&quot;DongJr&quot; /&gt;

&lt;/RelativeLayout&gt;
</code></pre><h4 id="2-menu"><a href="#2-menu" class="headerlink" title="2.menu"></a>2.menu</h4><pre><code>&lt;menu xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;&gt;

&lt;group android:checkableBehavior=&quot;single&quot;&gt;
    &lt;item
        android:id=&quot;@+id/nav_home&quot;
        android:icon=&quot;@mipmap/ic_dashboard&quot;
        android:title=&quot;Home&quot;/&gt;
    &lt;item
        android:id=&quot;@+id/nav_messages&quot;
        android:icon=&quot;@mipmap/ic_event&quot;
        android:title=&quot;Messages&quot;/&gt;
    &lt;item
        android:id=&quot;@+id/nav_friends&quot;
        android:icon=&quot;@mipmap/ic_headset&quot;
        android:title=&quot;Friends&quot;/&gt;
    &lt;item
        android:id=&quot;@+id/nav_discussion&quot;
        android:icon=&quot;@mipmap/ic_forum&quot;
        android:title=&quot;Discussion&quot;/&gt;
&lt;/group&gt;

&lt;item android:title=&quot;Sub items&quot;&gt;
    &lt;menu&gt;
        &lt;item
            android:id=&quot;@+id/sub_item1&quot;
            android:icon=&quot;@mipmap/ic_dashboard&quot;
            android:title=&quot;Sub item 1&quot;/&gt;
        &lt;item
            android:id=&quot;@+id/sub_item2&quot;
            android:icon=&quot;@mipmap/ic_forum&quot;
            android:title=&quot;Sub item 2&quot;/&gt;
    &lt;/menu&gt;
&lt;/item&gt;
&lt;/menu&gt;
</code></pre><p>写好布局后，我们就可以看到效果了。使用起来是不是很方便呢，当然，你也可以调整布局，达到自己想要的效果。</p>
<h3 id="代码实现："><a href="#代码实现：" class="headerlink" title="代码实现："></a>代码实现：</h3><h4 id="设置菜单栏监听。"><a href="#设置菜单栏监听。" class="headerlink" title="设置菜单栏监听。"></a>设置菜单栏监听。</h4><figure class="highlight groovy"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div><div class="line">35</div><div class="line">36</div></pre></td><td class="code"><pre><div class="line">mNavigationView.setNavigationItemSelectedListener(<span class="keyword">this</span>);  </div><div class="line"></div><div class="line"><span class="meta">@Override</span></div><div class="line">    <span class="keyword">public</span> <span class="keyword">boolean</span> onNavigationItemSelected(MenuItem item) &#123;</div><div class="line">        <span class="keyword">switch</span> (item.getItemId()) &#123;</div><div class="line">            <span class="keyword">case</span> R.id.<span class="string">nav_home:</span></div><div class="line">                SlothUtil.showToast(<span class="string">"HOME"</span>);</div><div class="line">                mDrawerLayout.closeDrawer(Gravity.LEFT);</div><div class="line">                startActivity(<span class="keyword">new</span> Intent(<span class="keyword">this</span>,HomeActivity.<span class="keyword">class</span>));</div><div class="line">                <span class="keyword">break</span>;</div><div class="line">            <span class="keyword">case</span> R.id.<span class="string">nav_messages:</span></div><div class="line">                SlothUtil.showToast(<span class="string">"MESSAGE"</span>);</div><div class="line">                mDrawerLayout.closeDrawer(Gravity.LEFT);</div><div class="line">                startActivity(<span class="keyword">new</span> Intent(<span class="keyword">this</span>,MessageActivity.<span class="keyword">class</span>));</div><div class="line">                <span class="keyword">break</span>;</div><div class="line">            <span class="keyword">case</span> R.id.<span class="string">nav_friends:</span></div><div class="line">                SlothUtil.showToast(<span class="string">"FRIENDS"</span>);</div><div class="line">                mDrawerLayout.closeDrawer(Gravity.LEFT);</div><div class="line">                startActivity(<span class="keyword">new</span> Intent(<span class="keyword">this</span>,FriendActivity.<span class="keyword">class</span>));</div><div class="line">                <span class="keyword">break</span>;</div><div class="line">            <span class="keyword">case</span> R.id.<span class="string">nav_discussion:</span></div><div class="line">                SlothUtil.showToast(<span class="string">"DISCUSSION"</span>);</div><div class="line">                mDrawerLayout.closeDrawer(Gravity.LEFT);</div><div class="line">                startActivity(<span class="keyword">new</span> Intent(<span class="keyword">this</span>,DiscussionActivity.<span class="keyword">class</span>));</div><div class="line">                <span class="keyword">break</span>;</div><div class="line">            <span class="keyword">case</span> R.id.<span class="string">sub_item1:</span></div><div class="line">                SlothUtil.showToast(<span class="string">"SUB_ITEM1"</span>);</div><div class="line">                mDrawerLayout.closeDrawer(Gravity.LEFT);</div><div class="line">                <span class="keyword">break</span>;</div><div class="line">            <span class="keyword">case</span> R.id.<span class="string">sub_item2:</span></div><div class="line">                SlothUtil.showToast(<span class="string">"SUB_ITEM2"</span>);</div><div class="line">                mDrawerLayout.closeDrawer(Gravity.LEFT);</div><div class="line">                <span class="keyword">break</span>;</div><div class="line">        &#125;</div><div class="line">        <span class="keyword">return</span> <span class="literal">false</span>;</div><div class="line">    &#125;</div></pre></td></tr></table></figure>
<h3 id="下面来讲解设置Toolbar和DrawerLayout的监听。"><a href="#下面来讲解设置Toolbar和DrawerLayout的监听。" class="headerlink" title="下面来讲解设置Toolbar和DrawerLayout的监听。"></a>下面来讲解设置Toolbar和DrawerLayout的监听。</h3><p>就是我们常见的三个横杠变箭头，然后菜单栏滑出的效果。<br>这里需要用到ActionBarDrawerToggle这个类。  </p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div></pre></td><td class="code"><pre><div class="line"></div><div class="line"> <span class="function"><span class="keyword">private</span> <span class="keyword">void</span> <span class="title">initDrawLayout</span><span class="params">()</span> </span>&#123;</div><div class="line">       <span class="comment">//DrawerLayout和Toolbar关联</span></div><div class="line">       mDrawerToggle = <span class="keyword">new</span> ActionBarDrawerToggle(<span class="keyword">this</span>, mDrawerLayout, mainToolbar, R.string.app_name, R.string.app_name);</div><div class="line">       mDrawerLayout.setDrawerListener(mDrawerToggle);</div><div class="line"></div><div class="line">      mainToolbar.setNavigationOnClickListener(<span class="keyword">new</span> View.OnClickListener() &#123;</div><div class="line">          <span class="meta">@Override</span></div><div class="line">          <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">onClick</span><span class="params">(View v)</span> </span>&#123;</div><div class="line">              <span class="keyword">if</span> (mDrawerLayout.isDrawerOpen(Gravity.LEFT)) &#123;</div><div class="line">                  mDrawerLayout.closeDrawer(Gravity.LEFT);</div><div class="line">              &#125; <span class="keyword">else</span> &#123;</div><div class="line">                  mDrawerLayout.openDrawer(Gravity.LEFT);</div><div class="line">              &#125;</div><div class="line">          &#125;</div><div class="line">      &#125;);</div><div class="line"></div><div class="line">      mNavigationView.setNavigationItemSelectedListener(<span class="keyword">this</span>);</div><div class="line">  &#125;</div><div class="line"></div><div class="line"></div><div class="line"><span class="comment">/**</span></div><div class="line">    * Activity彻底运行起来之后的回调</div><div class="line">    * Called when activity start-up is complete</div><div class="line">    * (after onStart() and onRestoreInstanceState(Bundle) have been called).</div><div class="line">    */</div><div class="line">   <span class="meta">@Override</span></div><div class="line">   <span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">onPostCreate</span><span class="params">(Bundle savedInstanceState)</span> </span>&#123;</div><div class="line">       <span class="keyword">super</span>.onPostCreate(savedInstanceState);</div><div class="line">       <span class="comment">//箭头旋转动画的关键</span></div><div class="line">       mDrawerToggle.syncState();</div><div class="line">   &#125;</div></pre></td></tr></table></figure>
<p>DrawerLayout，NavigationView的用法讲解结束，有兴趣的同学可以查看源代码——Meterial Design的控件Demo。</p>
<h3 id="https-github-com-JrDong-Android-Sloth"><a href="#https-github-com-JrDong-Android-Sloth" class="headerlink" title="https://github.com/JrDong/Android-Sloth"></a><a href="https://github.com/JrDong/Android-Sloth" target="_blank" rel="external">https://github.com/JrDong/Android-Sloth</a></h3>]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;Material-Design控件介绍（一）———Toolbar-DrawerLayout-NavigationView&quot;&gt;&lt;a href=&quot;#Material-Design控件介绍（一）———Toolbar-DrawerLayout-NavigationView
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
  </entry>
  
  <entry>
    <title>Material Design介绍</title>
    <link href="http://ibat.xyz/2016/04/09/Material%20Design%E4%BB%8B%E7%BB%8D/"/>
    <id>http://ibat.xyz/2016/04/09/Material Design介绍/</id>
    <published>2016-04-09T14:33:06.000Z</published>
    <updated>2016-06-28T13:27:45.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="Material-Design介绍"><a href="#Material-Design介绍" class="headerlink" title="Material Design介绍"></a>Material Design介绍</h1><h2 id="背景"><a href="#背景" class="headerlink" title="背景"></a>背景</h2><p>在Google I/O大会上Google引入了Material Design。Material Design是一门用户界面视觉设计语言。可以基于智能手机，平板，电视等等设备。从我的角度理解，Material Design其实就是Google为我们提供的一种设计规范。<br>我们可以发现在之前的软件中，许多IOS的软件，都有一些相似的共性。但Android 软件却各有各的特点。这应该也是Google推出Material Design的初衷之一吧。统一Android应用的设计规范，让应用更加清爽，有设计感。<br>Material Design设计灵感来源与对纸和墨水的研究，用纸张拼接来作为交互手段。</p>
<h2 id="介绍"><a href="#介绍" class="headerlink" title="介绍"></a>介绍</h2><p>从Material Design文档中可以看出一下几点Material Design特点：</p>
<h3 id="1-3D效果"><a href="#1-3D效果" class="headerlink" title="1.3D效果"></a>1.3D效果</h3><p>谷歌推出了立体视觉的概念，也是Material Design中最重要的概念。从许多控件比如CardView，FloatingActionButton等都可以看出，添加了对高度的设置。如果说之前的设计效果只是基于x，y轴设计的话，Material Design则添加了z轴的概念。如下图<br><img src="/img/62b809272022724eac120be1587b04de_r.jpg" alt="Alt text"></p>
<h3 id="2-亮度和阴影（以FloatingActionButton为例）"><a href="#2-亮度和阴影（以FloatingActionButton为例）" class="headerlink" title="2.亮度和阴影（以FloatingActionButton为例）"></a>2.亮度和阴影（以FloatingActionButton为例）</h3><figure class="image-bubble">
                <div class="img-lightbox">
                    <div class="overlay"></div>
                    <img src="/img/5083a5b853a84385b6ddce356016c57b_r.jpg" alt="Alt text" title="">
                </div>
                <div class="image-caption">Alt text</div>
            </figure>
<h3 id="3-压缩和拉伸-CollapsingToolbarLayout效果，之后会讲"><a href="#3-压缩和拉伸-CollapsingToolbarLayout效果，之后会讲" class="headerlink" title="3.压缩和拉伸(CollapsingToolbarLayout效果，之后会讲)"></a>3.压缩和拉伸(CollapsingToolbarLayout效果，之后会讲)</h3><h3 id="4-水波纹效果："><a href="#4-水波纹效果：" class="headerlink" title="4.水波纹效果："></a>4.水波纹效果：</h3><p>这个效果经常可以见到，在Android 5.0的手机上，点击button后的波纹扩散效果。</p>
<p>……颜色，动画，布局，样式等等，在之后讲解控件时再详细介绍。<br>总的来说，Material Design 为我们一共了一系列的规范，希望我们通过这套规范，设计出更简洁，更高大上的应用。设计和产品同学可以看看这套规范，google已经设计好了很多东西。</p>
<h3 id="图片素材推荐："><a href="#图片素材推荐：" class="headerlink" title="图片素材推荐："></a>图片素材推荐：</h3><p>参考 <a href="https://design.google.com/icons/" target="_blank" rel="external">https://design.google.com/icons/</a></p>
<h3 id="颜色规范参考："><a href="#颜色规范参考：" class="headerlink" title="颜色规范参考："></a>颜色规范参考：</h3><p><a href="https://www.google.com/design/spec/style/color.html#" target="_blank" rel="external">https://www.google.com/design/spec/style/color.html#</a></p>
<h3 id="更多Material-Design规范参考："><a href="#更多Material-Design规范参考：" class="headerlink" title="更多Material Design规范参考："></a>更多Material Design规范参考：</h3><p><a href="https://www.google.com/design/spec/material-design/introduction.html" target="_blank" rel="external">https://www.google.com/design/spec/material-design/introduction.html</a></p>
<h3 id="我的Material-Design-Demo"><a href="#我的Material-Design-Demo" class="headerlink" title="我的Material-Design  Demo"></a>我的Material-Design  Demo</h3><p><a href="https://github.com/JrDong/Android-Sloth,其中用到了大部分的md控件。欢迎fork" target="_blank" rel="external">https://github.com/JrDong/Android-Sloth,其中用到了大部分的md控件。欢迎fork</a></p>
]]></content>
    
    <summary type="html">
    
      &lt;h1 id=&quot;Material-Design介绍&quot;&gt;&lt;a href=&quot;#Material-Design介绍&quot; class=&quot;headerlink&quot; title=&quot;Material Design介绍&quot;&gt;&lt;/a&gt;Material Design介绍&lt;/h1&gt;&lt;h2 id=&quot;背景&quot;&gt;&lt;
    
    </summary>
    
      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
  </entry>
  
  <entry>
    <title>OAuth2.0协议&amp;第三方登录（微信，QQ，微博）</title>
    <link href="http://ibat.xyz/2016/03/08/OAuth2.0%E5%8D%8F%E8%AE%AE&amp;%E7%AC%AC%E4%B8%89%E6%96%B9%E7%99%BB%E5%BD%95/"/>
    <id>http://ibat.xyz/2016/03/08/OAuth2.0协议&amp;第三方登录/</id>
    <published>2016-03-08T13:12:05.000Z</published>
    <updated>2016-05-11T13:19:21.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="OAuth2-0协议-amp-第三方登录（微信，QQ，微博）"><a href="#OAuth2-0协议-amp-第三方登录（微信，QQ，微博）" class="headerlink" title="OAuth2.0协议&amp;第三方登录（微信，QQ，微博）"></a>OAuth2.0协议&amp;第三方登录（微信，QQ，微博）</h1><h2 id="OAuth-2-0协议"><a href="#OAuth-2-0协议" class="headerlink" title="OAuth 2.0协议"></a>OAuth 2.0协议</h2><h3 id="1-应用场景"><a href="#1-应用场景" class="headerlink" title="1.应用场景"></a>1.应用场景</h3><p>OAuth 2.0是一个关于授权的开放标准。<br>假如某个应用需要得到你的授权，如果不使用OAuth2.0协议，会要求输入账号密码。这样就带来了一些问题：  </p>
<blockquote>
<ol>
<li>第三方应用会保存用户的账户和密码，这样很不安全。  </li>
<li>用户没法限制第三方应用的授权范围和有效期。  </li>
<li>用户只有修改密码才会取消授权，但这样的话会使其他的第三方授权也失效。  </li>
<li>如果第三方应用被破解，那么就会导致用户密码泄露，和数据泄露。  </li>
</ol>
</blockquote>
<p>使用OAuth 2.0就不会出现上述问题了。</p>
<h3 id="2-OAuth思路"><a href="#2-OAuth思路" class="headerlink" title="2.OAuth思路"></a>2.OAuth思路</h3><p>OAuth在”客户端”与”服务提供商”之间，设置了一个授权层（authorization layer）。<br>“客户端”不能直接登录”服务提供商”，只能登录授权层，以此将用户与客户端区分开来。”客户端”登录授权层所用的令牌（token），与用户的密码不同。用户可以在登录的时候，指定授权层令牌的权限范围和有效期。（一般是开发时指定scope，规定权限范围。）<br>“客户端”登录授权层以后，”服务提供商”根据令牌的权限范围和有效期，向”客户端”开放用户储存的资料。这个令牌授权“客户端”在特定时间内（assert_token具有有效期）访问特定资源。这样就恰如其分的控制了第三方应用所获取的权限。</p>
<h3 id="3-运行流程"><a href="#3-运行流程" class="headerlink" title="3.运行流程"></a>3.运行流程</h3><blockquote>
<p>1.打开客户端后，客户端要求用户授权<br>2.用户同意授权<br>3.客户端使用授权，向认证服务器（第三方认证服务器）申请令牌<br>4.认证服务器进行认证后，同意发放令牌<br>5.用户使用令牌，向资源服务器申请资源(第三方资源服务器，可以是一个服务器，也可以是两个)<br>6.资源服务器确认令牌无误，同意向客户端开放资源 </p>
</blockquote>
<p><img src="file:///C:/Users/aidonglei/Desktop/OAuth授权流程.jpg" alt="Alt text"></p>
<h2 id="微信登录"><a href="#微信登录" class="headerlink" title="微信登录"></a>微信登录</h2><blockquote>
<p>0.个人感觉微信登录最大的难点在回调上，如果接收不到回调，请确认1，2两点。并仔细检查应用的签名和包名，和在微信开放平台申请时候的完全一致。<br>1.在AndroidManifest.xml中配置，其中Theme.NoDisplay代表透明主题。</p>
</blockquote>
<pre><code>&lt;activity
        android:name=&quot;com.xywy.xytrain.wxapi.WXEntryActivity&quot;
        android:exported=&quot;true&quot;
        android:configChanges=&quot;keyboardHidden|orientation|screenSize&quot;
        android:launchMode=&quot;singleTop&quot;
        android:theme=&quot;@android:style/Theme.NoDisplay&quot;
        android:screenOrientation=&quot;portrait&quot;/&gt;
</code></pre><blockquote>
<p>2.在主项目跟目录下（包名下的目录）,新建wxapi文件夹，并创建WXEntryActivity，继承activity。必须在跟目录下，不然无法回调。<br>3.微信提供了两个回调类onReq和onResp，客户端将消息发送的微信会回调onReq，从微信接受到消息会回调onResp。在onResp回调方法里，可以得到ErrCode，code等参数，通过ErrCode可以判断用户行为，通过Code可以换取access_token，这个code只有在ErrCode为0时才有效。</p>
</blockquote>
<h2 id="QQ登录"><a href="#QQ登录" class="headerlink" title="QQ登录"></a>QQ登录</h2><p>1.QQ登录相比较微信登录要简单点，初始化QQ,和IUiListener回调</p>
<pre><code>if (mTencent == null) {
       mTencent = Tencent.createInstance(MineConstants.QQAPP_ID, getContext());
   }
</code></pre><p>2.在进行登录的activity中重写OnActivityResult方法  </p>
<figure class="highlight haskell"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div></pre></td><td class="code"><pre><div class="line">@<span class="type">Override</span></div><div class="line"> protected void onActivityResult(int requestCode, int resultCode, <span class="type">Intent</span> <span class="class"><span class="keyword">data</span>) &#123;</span></div><div class="line">     //一定要在与<span class="title">fragment</span>绑定的<span class="title">activity</span>中重写此方法，不然无法回调</div><div class="line">     <span class="title">if</span> (<span class="title">requestCode</span> == <span class="type">Constants</span>.<span class="type">REQUEST_API</span> ||</div><div class="line">             <span class="title">requestCode</span> == <span class="type">Constants</span>.<span class="type">REQUEST_LOGIN</span>) &#123;</div><div class="line">         <span class="type">Tencent</span>.<span class="title">handleResultData</span>(<span class="title">data</span>, <span class="type">ThirdLoginFragment</span>.<span class="title">mTencentListener</span>);</div><div class="line">     &#125;</div><div class="line"> &#125;</div></pre></td></tr></table></figure>
<p>3.IUiListener中有三个回调方法，onComplete(Object response)授权成功调用,onError(UiError e)授权失败调用,onCancel()授权取消调用.onComplete中的response是一个JsonObject，里面含有OpenId， AccessToken等参数，通过参数就可以取得用户信息。<br>4.注意一点，QQ文档中介绍，只需要在AndroidManifest.xml中配置</p>
<pre><code>&lt;activity
        android:name=&quot;com.tencent.tauth.AuthActivity&quot;
        android:launchMode=&quot;singleTask&quot;
        android:noHistory=&quot;true&quot;&gt;
        &lt;intent-filter&gt;
            &lt;action android:name=&quot;android.intent.action.VIEW&quot; /&gt;

            &lt;category android:name=&quot;android.intent.category.DEFAULT&quot; /&gt;
            &lt;category android:name=&quot;android.intent.category.BROWSABLE&quot; /&gt;

            &lt;data android:scheme=&quot;tencent+&quot;your appid&quot;&quot; /&gt;
        &lt;/intent-filter&gt;
    &lt;/activity&gt;
</code></pre><p>但如果使用最新的sdk还需要配置以下内容，这点在文档中没有介绍，走了一点弯路。</p>
<pre><code>&lt;activity
       android:name=&quot;com.tencent.connect.common.AssistActivity&quot;
       android:screenOrientation=&quot;portrait&quot;
       android:theme=&quot;@android:style/Theme.Translucent.NoTitleBar&quot; /&gt;
</code></pre><h2 id="微博登录"><a href="#微博登录" class="headerlink" title="微博登录"></a>微博登录</h2><p>1.微博登录文档写的比较详细，大家看文档就可以了。<a href="https://github.com/sinaweibosdk/weibo_android_sdk" target="_blank" rel="external">https://github.com/sinaweibosdk/weibo_android_sdk</a><br>2.注意一点，如果把第三方登录放入子项目中，微博的jni文件需要放在main目录下，不然会找不到jni文件。</p>
]]></content>
    
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      &lt;h1 id=&quot;OAuth2-0协议-amp-第三方登录（微信，QQ，微博）&quot;&gt;&lt;a href=&quot;#OAuth2-0协议-amp-第三方登录（微信，QQ，微博）&quot; class=&quot;headerlink&quot; title=&quot;OAuth2.0协议&amp;amp;第三方登录（微信，QQ，微博）&quot;&gt;
    
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      <category term="Android" scheme="http://ibat.xyz/categories/Android/"/>
    
    
  </entry>
  
  <entry>
    <title>markdown语法</title>
    <link href="http://ibat.xyz/2016/01/27/markdown%E8%AF%AD%E6%B3%95/"/>
    <id>http://ibat.xyz/2016/01/27/markdown语法/</id>
    <published>2016-01-27T14:14:00.000Z</published>
    <updated>2016-05-09T12:59:41.000Z</updated>
    
    <content type="html"><![CDATA[<h1 id="使用Markdown写博客"><a href="#使用Markdown写博客" class="headerlink" title="使用Markdown写博客"></a>使用Markdown写博客</h1><h2 id="Markdown基本语法"><a href="#Markdown基本语法" class="headerlink" title="Markdown基本语法"></a>Markdown基本语法</h2><h3 id="标题"><a href="#标题" class="headerlink" title="标题"></a>标题</h3><pre><code>＃——###### 分别代表 h1--h6
比如 #### text
</code></pre><h4 id="text"><a href="#text" class="headerlink" title="text"></a>text</h4><h3 id="区块引用"><a href="#区块引用" class="headerlink" title="区块引用"></a>区块引用</h3><pre><code>1.可以在每一行都加上引用，也可以只在段落之前加上引用
&gt; 这里填写要引用的文字
2.区块引用可以嵌套
&gt;&gt; 这里填写要嵌套的文字
3.区块内部也可以使用其他语法
&gt; #### text
</code></pre><blockquote>
<p>这里是正文</p>
<blockquote>
<p>这里填写要引用的文字</p>
<p>####text</p>
</blockquote>
</blockquote>
<h3 id="列表"><a href="#列表" class="headerlink" title="列表"></a>列表</h3><h5 id="无序列表"><a href="#无序列表" class="headerlink" title="无序列表"></a>无序列表</h5><pre><code>*号之前加上制表符会有多级效果

* 苹果
* 香蕉
    * 梨
</code></pre><p><strong>另外：* + - 三者效果相同    </strong></p>
<ul>
<li>苹果</li>
<li>香蕉<ul>
<li>梨  </li>
</ul>
</li>
</ul>
<h5 id="有序列表"><a href="#有序列表" class="headerlink" title="有序列表"></a>有序列表</h5><pre><code>使用数字加上英文句点
1. 苹果
2. 香蕉
3. 梨
6. 草莓
</code></pre><p><strong>另外注意一点，列表标记的数字并不会影响结果，即使是乱序排列，Markdown也会自动排序成有序的</strong>  </p>
<ol>
<li>苹果</li>
<li>香蕉</li>
<li>梨</li>
<li>草莓</li>
</ol>
<h3 id="其他"><a href="#其他" class="headerlink" title="其他"></a>其他</h3><ul>
<li>强制换行，在语句后面加上两个空格</li>
<li>用markdown语法时，在关键字符后面尽量加上空格，不然可能语句会不生效，例如 # text</li>
</ul>
<h2 id="Markdown及扩展"><a href="#Markdown及扩展" class="headerlink" title="Markdown及扩展"></a>Markdown及扩展</h2><h3 id="标记语言"><a href="#标记语言" class="headerlink" title="标记语言"></a>标记语言</h3><pre><code>&gt; Markdown 是一种轻量级标记语言，它允许人们使用易读易写的纯文本格式编写文档，然后转换成格式丰富的HTML页面。      
—— &lt;a href=&quot;https://zh.wikipedia.org/wiki/Markdown&quot; target=&quot;_blank&quot;&gt; [ 维基百科 ]
</code></pre><blockquote>
<p>Markdown 是一种轻量级标记语言，它允许人们使用易读易写的纯文本格式编写文档，然后转换成格式丰富的HTML页面。    —— <a href="https://zh.wikipedia.org/wiki/Markdown" target="_blank"> [ 维基百科 ]    </a></p>
</blockquote>
<h3 id="字体，链接"><a href="#字体，链接" class="headerlink" title="字体，链接"></a>字体，链接</h3><pre><code>使用简单的符号标识不同的标题，将某些文字标记为**粗体**或者*斜体*，创建一个[链接](http://ibat.xyz)等
</code></pre><p>使用简单的符号标识不同的标题，将某些文字标记为<strong>粗体</strong>或者<em>斜体</em>，创建一个<a href="http://ibat.xyz">链接</a>等</p>
<h3 id="表格"><a href="#表格" class="headerlink" title="表格"></a>表格</h3><p><strong>Markdown</strong>　表格语法：  </p>
<pre><code>项目     | 价格  
-------- | ---  
Computer | $1600  
iPhone    | $12  
iPad     | $1  
</code></pre><table>
<thead>
<tr>
<th>项目</th>
<th>价格</th>
</tr>
</thead>
<tbody>
<tr>
<td>Computer</td>
<td>$1600</td>
</tr>
<tr>
<td>iPhone</td>
<td>$12</td>
</tr>
<tr>
<td>iPad</td>
<td>$1</td>
</tr>
</tbody>
</table>
<p><strong>可以使用冒号来定义对齐方式：</strong></p>
<pre><code>| 项目      |    价格 | 数量  |  
| :-------- | --------:| :--: |  
|左对齐        |右对齐        |居中    |
| Computer  | 1600 元 |  5   |  
| iPhone     |   12 元 |  12  |  
| iPad      |    1 元 | 234  |      
</code></pre><table>
<thead>
<tr>
<th style="text-align:left">项目</th>
<th style="text-align:right">价格</th>
<th style="text-align:center">数量</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align:left">左对齐</td>
<td style="text-align:right">右对齐</td>
<td style="text-align:center">居中</td>
</tr>
<tr>
<td style="text-align:left">Computer</td>
<td style="text-align:right">1600 元</td>
<td style="text-align:center">5</td>
</tr>
<tr>
<td style="text-align:left">iPhone</td>
<td style="text-align:right">12 元</td>
<td style="text-align:center">12</td>
</tr>
<tr>
<td style="text-align:left">iPad</td>
<td style="text-align:right">1 元</td>
<td style="text-align:center">234</td>
</tr>
</tbody>
</table>
<h3 id="代码块"><a href="#代码块" class="headerlink" title="代码块"></a>代码块</h3><p><strong>代码块语法遵循标准markdown代码，例如：</strong><br>  ``` python(这里写哪种语言)<br>  代码块<br>  ```   </p>
 <figure class="highlight python"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div></pre></td><td class="code"><pre><div class="line"><span class="meta">@requires_authorization</span></div><div class="line"><span class="function"><span class="keyword">def</span> <span class="title">somefunc</span><span class="params">(param1=<span class="string">''</span>, param2=<span class="number">0</span>)</span>:</span></div><div class="line">    <span class="string">'''A docstring'''</span></div><div class="line">    <span class="keyword">if</span> param1 &gt; param2: <span class="comment"># interesting</span></div><div class="line">        <span class="keyword">print</span> <span class="string">'Greater'</span></div><div class="line">    <span class="keyword">return</span> (param2 - param1 + <span class="number">1</span>) <span class="keyword">or</span> <span class="keyword">None</span></div><div class="line"><span class="class"><span class="keyword">class</span> <span class="title">SomeClass</span>:</span></div><div class="line">    <span class="keyword">pass</span></div><div class="line"><span class="meta">&gt;&gt;&gt; </span>message = <span class="string">'''interpreter</span></div><div class="line"><span class="meta">... </span>prompt'''</div></pre></td></tr></table></figure>
<p><strong>简单的四个空格或者一个制表符生成代码块</strong>  </p>
<pre><code>这里放代码区块
</code></pre><h3 id="图片"><a href="#图片" class="headerlink" title="图片"></a>图片</h3><p>很明显地，要在纯文字应用中设计一个「自然」的语法来插入图片是有一定难度的。</p>
<p>Markdown 使用一种和链接很相似的语法来标记图片，同样也允许两种样式： 行内式和参考式。</p>
<p>行内式的图片语法看起来像是：</p>
<pre><code>![Alt text](/path/to/img.jpg)

{% image /path/to/img.jpg 'Alt text' 'Optional' %}  
</code></pre><p>详细叙述如下：</p>
<pre><code>一个惊叹号 !  
接着一个方括号，里面放上图片的替代文字（可以不填）  
接着一个普通括号，里面放上图片的网址，最后还可以用引号包住并加上 选择性的 &apos;title&apos; 文字。  
参考式的图片语法则长得像这样：  

![Alt text][id]
</code></pre><p>到目前为止， Markdown 还没有办法指定图片的宽高，如果你需要的话，你可以使用普通的 <img> 标签。</p>
<ul>
<li>关于 <strong>序列图</strong> 语法，参考 <a href="http://bramp.github.io/js-sequence-diagrams/" target="_blank" rel="external">这儿</a>,</li>
<li>关于 <strong>流程图</strong> 语法，参考 <a href="http://adrai.github.io/flowchart.js/" target="_blank" rel="external">这儿</a>.</li>
</ul>
<p>先写到这里，有新的东西再继续补充。</p>
<hr>
]]></content>
    
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      &lt;h1 id=&quot;使用Markdown写博客&quot;&gt;&lt;a href=&quot;#使用Markdown写博客&quot; class=&quot;headerlink&quot; title=&quot;使用Markdown写博客&quot;&gt;&lt;/a&gt;使用Markdown写博客&lt;/h1&gt;&lt;h2 id=&quot;Markdown基本语法&quot;&gt;&lt;a href
    
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