Android5.0+(CoordinatorLayout)

英文原文：https://guides.codepath.com/android/Handling-Scrolls-with-CoordinatorLayout

这篇文章专门讲解和CoordinatorLayout相关的知识点，这也是Design Support Library中最重要与最难的部分。

概览

CoordinatorLayout 实现了多种Material Design中提到的滚动效果。目前这个框架提供了几种不用写动画代码就能工作的方法，这些效果包括：

让浮动操作按钮上下滑动，为Snackbar留出空间。

扩展或者缩小Toolbar或者头部，让主内容区域有更多的空间。

控制哪个view应该扩展还是收缩，以及其显示大小比例，包括视差滚动效果动画。

设置

首先确保遵循了Design Support Library的使用说明。

浮动操作按钮与Snackbar

CoordinatorLayout可以用来配合浮动操作按钮的 layout_anchor 和 layout_gravity属性创造出浮动效果，详情请参见浮动操作按钮指南。

当Snackbar在显示的时候，往往出现在屏幕的底部。为了给Snackbar留出空间，浮动操作按钮需要向上移动。

只要使用CoordinatorLayout作为基本布局，将自动产生向上移动的动画。浮动操作按钮有一个默认的 behavior来检测Snackbar的添加并让按钮在Snackbar之上呈现上移与Snackbar等高的动画。

  <table border="0" cellspacing="0" cellpadding="0">
    <tr>
      <td class="gutter">
        <div class="line number1 index0 alt2">
          1
        </div>
        
        <div class="line number2 index1 alt1">
          2
        </div>
        
        <div class="line number3 index2 alt2">
          3
        </div>
        
        <div class="line number4 index3 alt1">
          4
        </div>
        
        <div class="line number5 index4 alt2">
          5
        </div>
        
        <div class="line number6 index5 alt1">
          6
        </div>
        
        <div class="line number7 index6 alt2">
          7
        </div>
        
        <div class="line number8 index7 alt1">
          8
        </div>
        
        <div class="line number9 index8 alt2">
          9
        </div>
        
        <div class="line number10 index9 alt1">
          10
        </div>
        
        <div class="line number11 index10 alt2">
          11
        </div>
        
        <div class="line number12 index11 alt1">
          12
        </div>
        
        <div class="line number13 index12 alt2">
          13
        </div>
        
        <div class="line number14 index13 alt1">
          14
        </div>
        
        <div class="line number15 index14 alt2">
          15
        </div>
        
        <div class="line number16 index15 alt1">
          16
        </div>
        
        <div class="line number17 index16 alt2">
          17
        </div>
        
        <div class="line number18 index17 alt1">
          18
        </div>
        
        <div class="line number19 index18 alt2">
          19
        </div>
        
        <div class="line number20 index19 alt1">
          20
        </div>
        
        <div class="line number21 index20 alt2">
          21
        </div>
        
        <div class="line number22 index21 alt1">
          22
        </div>
      </td>
      
      <td class="code">
        <div class="container">
          <div class="line number1 index0 alt2">
            ` ``&lt;``android.support.design.widget.CoordinatorLayout`
          </div>
          
          <div class="line number2 index1 alt1">
            `        ``android:id``=``"@+id/main_content"`
          </div>
          
          <div class="line number3 index2 alt2">
            `        ``xmlns:android``=``"http://schemas.android.com/apk/res/android"`
          </div>
          
          <div class="line number4 index3 alt1">
            `        ``xmlns:app``=``"http://schemas.android.com/apk/res-auto"`
          </div>
          
          <div class="line number5 index4 alt2">
            `        ``android:layout_width``=``"match_parent"`
          </div>
          
          <div class="line number6 index5 alt1">
            `        ``android:layout_height``=``"match_parent"``&gt;`
          </div>
          
          <div class="line number7 index6 alt2">
            ` `
          </div>
          
          <div class="line number8 index7 alt1">
            `   ``&lt;``android.support.v7.widget.RecyclerView`
          </div>
          
          <div class="line number9 index8 alt2">
            `         ``android:id``=``"@+id/rvToDoList"`
          </div>
          
          <div class="line number10 index9 alt1">
            `         ``android:layout_width``=``"match_parent"`
          </div>
          
          <div class="line number11 index10 alt2">
            `         ``android:layout_height``=``"match_parent"``&gt;`
          </div>
          
          <div class="line number12 index11 alt1">
            `   ``&lt;/``android.support.v7.widget.RecyclerView``&gt;`
          </div>
          
          <div class="line number13 index12 alt2">
            ` `
          </div>
          
          <div class="line number14 index13 alt1">
            `   ``&lt;``android.support.design.widget.FloatingActionButton`
          </div>
          
          <div class="line number15 index14 alt2">
            `        ``android:layout_width``=``"wrap_content"`
          </div>
          
          <div class="line number16 index15 alt1">
            `        ``android:layout_height``=``"wrap_content"`
          </div>
          
          <div class="line number17 index16 alt2">
            `        ``android:layout_gravity``=``"bottom|right"`
          </div>
          
          <div class="line number18 index17 alt1">
            `        ``android:layout_margin``=``"16dp"`
          </div>
          
          <div class="line number19 index18 alt2">
            `        ``android:src``=``"@mipmap/ic_launcher"`
          </div>
          
          <div class="line number20 index19 alt1">
            `        ``app:layout_anchor``=``"@id/rvToDoList"`
          </div>
          
          <div class="line number21 index20 alt2">
            `        ``app:layout_anchorGravity``=``"bottom|right|end"``/&gt;`
          </div>
          
          <div class="line number22 index21 alt1">
            ` ``&lt;/``android.support.design.widget.CoordinatorLayout``&gt;`
          </div>
        </div>
      </td>
    </tr>
  </table>
</div>

Toolbar的扩展与收缩

首先需要确保你不是使用已经过时的ActionBar。务必遵循使用ToolBar作为actionbar这篇文章的指南。同样，这里也需要CoordinatorLayout作为主布局容器。

  <table border="0" cellspacing="0" cellpadding="0">
    <tr>
      <td class="gutter">
        <div class="line number1 index0 alt2">
          1
        </div>
        
        <div class="line number2 index1 alt1">
          2
        </div>
        
        <div class="line number3 index2 alt2">
          3
        </div>
        
        <div class="line number4 index3 alt1">
          4
        </div>
        
        <div class="line number5 index4 alt2">
          5
        </div>
        
        <div class="line number6 index5 alt1">
          6
        </div>
        
        <div class="line number7 index6 alt2">
          7
        </div>
        
        <div class="line number8 index7 alt1">
          8
        </div>
        
        <div class="line number9 index8 alt2">
          9
        </div>
        
        <div class="line number10 index9 alt1">
          10
        </div>
        
        <div class="line number11 index10 alt2">
          11
        </div>
        
        <div class="line number12 index11 alt1">
          12
        </div>
        
        <div class="line number13 index12 alt2">
          13
        </div>
        
        <div class="line number14 index13 alt1">
          14
        </div>
      </td>
      
      <td class="code">
        <div class="container">
          <div class="line number1 index0 alt2">
            `&lt;``android.support.design.widget.CoordinatorLayout` `xmlns:android``=``"http://schemas.android.com/apk/res/android"`
          </div>
          
          <div class="line number2 index1 alt1">
            ` ``xmlns:app``=``"http://schemas.android.com/apk/res-auto"`
          </div>
          
          <div class="line number3 index2 alt2">
            `    ``android:id``=``"@+id/main_content"`
          </div>
          
          <div class="line number4 index3 alt1">
            `    ``android:layout_width``=``"match_parent"`
          </div>
          
          <div class="line number5 index4 alt2">
            `    ``android:layout_height``=``"match_parent"`
          </div>
          
          <div class="line number6 index5 alt1">
            `    ``android:fitsSystemWindows``=``"true"``&gt;`
          </div>
          
          <div class="line number7 index6 alt2">
            ` `
          </div>
          
          <div class="line number8 index7 alt1">
            `      ``&lt;``android.support.v7.widget.Toolbar`
          </div>
          
          <div class="line number9 index8 alt2">
            `                ``android:id``=``"@+id/toolbar"`
          </div>
          
          <div class="line number10 index9 alt1">
            `                ``android:layout_width``=``"match_parent"`
          </div>
          
          <div class="line number11 index10 alt2">
            `                ``android:layout_height``=``"?attr/actionBarSize"`
          </div>
          
          <div class="line number12 index11 alt1">
            `                ``app:popupTheme``=``"@style/ThemeOverlay.AppCompat.Light"` `/&gt;`
          </div>
          
          <div class="line number13 index12 alt2">
            ` `
          </div>
          
          <div class="line number14 index13 alt1">
            `&lt;/``android.support.design.widget.CoordinatorLayout``&gt;`
          </div>
        </div>
      </td>
    </tr>
  </table>
</div>

接下来，我们必须使用一个容器布局： [AppBarLayout](http://developer.android.com/reference/android/support/design/widget/AppBarLayout.html) 来让Toolbar响应滚动事件。响应滚动事件</div> 

<div class="line number1 index0 alt2">
  <div>
    <div id="highlighter_994531" class="syntaxhighlighter  xml">
      <div class="toolbar">
        [?](http://my.oschina.net/kooeasy/blog/484593#)
      </div>
      
      <table border="0" cellspacing="0" cellpadding="0">
        <tr>
          <td class="gutter">
            <div class="line number1 index0 alt2">
              1
            </div>
            
            <div class="line number2 index1 alt1">
              2
            </div>
            
            <div class="line number3 index2 alt2">
              3
            </div>
            
            <div class="line number4 index3 alt1">
              4
            </div>
            
            <div class="line number5 index4 alt2">
              5
            </div>
            
            <div class="line number6 index5 alt1">
              6
            </div>
            
            <div class="line number7 index6 alt2">
              7
            </div>
            
            <div class="line number8 index7 alt1">
              8
            </div>
            
            <div class="line number9 index8 alt2">
              9
            </div>
            
            <div class="line number10 index9 alt1">
              10
            </div>
            
            <div class="line number11 index10 alt2">
              11
            </div>
            
            <div class="line number12 index11 alt1">
              12
            </div>
            
            <div class="line number13 index12 alt2">
              13
            </div>
            
            <div class="line number14 index13 alt1">
              14
            </div>
          </td>
          
          <td class="code">
            <div class="container">
              <div class="line number1 index0 alt2">
                `&lt;``android.support.design.widget.AppBarLayout`
              </div>
              
              <div class="line number2 index1 alt1">
                `        ``android:id``=``"@+id/appbar"`
              </div>
              
              <div class="line number3 index2 alt2">
                `        ``android:layout_width``=``"match_parent"`
              </div>
              
              <div class="line number4 index3 alt1">
                `        ``android:layout_height``=``"@dimen/detail_backdrop_height"`
              </div>
              
              <div class="line number5 index4 alt2">
                `        ``android:theme``=``"@style/ThemeOverlay.AppCompat.Dark.ActionBar"`
              </div>
              
              <div class="line number6 index5 alt1">
                `        ``android:fitsSystemWindows``=``"true"``&gt;`
              </div>
              
              <div class="line number7 index6 alt2">
                ` `
              </div>
              
              <div class="line number8 index7 alt1">
                `  ``&lt;``android.support.v7.widget.Toolbar`
              </div>
              
              <div class="line number9 index8 alt2">
                `                ``android:id``=``"@+id/toolbar"`
              </div>
              
              <div class="line number10 index9 alt1">
                `                ``android:layout_width``=``"match_parent"`
              </div>
              
              <div class="line number11 index10 alt2">
                `                ``android:layout_height``=``"?attr/actionBarSize"`
              </div>
              
              <div class="line number12 index11 alt1">
                `                ``app:popupTheme``=``"@style/ThemeOverlay.AppCompat.Light"` `/&gt;`
              </div>
              
              <div class="line number13 index12 alt2">
                ` `
              </div>
              
              <div class="line number14 index13 alt1">
                ` ``&lt;/``android.support.design.widget.AppBarLayout``&gt;`
              </div>
            </div>
          </td>
        </tr>
      </table>
    </div>
  </div>
</div>



  然后，我们需要定义AppBarLayout与滚动视图之间的联系。在RecyclerView或者任意支持嵌套滚动的view比如[NestedScrollView](http://stackoverflow.com/questions/25136481/what-are-the-new-nested-scrolling-apis-for-android-l)上添加app:layout_behavior。support library包含了一个特殊的字符串资源@string/appbar_scrolling_view_behavior，它和[AppBarLayout.ScrollingViewBehavior](https://developer.android.com/reference/android/support/design/widget/AppBarLayout.ScrollingViewBehavior.html)相匹配，用来通知AppBarLayout 这个特殊的view何时发生了滚动事件，这个behavior需要设置在触发事件（滚动）的view之上。注意：根据官方的[谷歌文档](http://developer.android.com/reference/android/support/design/widget/AppBarLayout.html)，AppBarLayout目前必须是第一个嵌套在CoordinatorLayout里面的子view。



<div class="line number1 index0 alt2">
  <div>
    <div id="highlighter_295670" class="syntaxhighlighter  xml">
      <div class="toolbar">
        [?](http://my.oschina.net/kooeasy/blog/484593#)
      </div>
      
      <table border="0" cellspacing="0" cellpadding="0">
        <tr>
          <td class="gutter">
            <div class="line number1 index0 alt2">
              1
            </div>
            
            <div class="line number2 index1 alt1">
              2
            </div>
            
            <div class="line number3 index2 alt2">
              3
            </div>
            
            <div class="line number4 index3 alt1">
              4
            </div>
            
            <div class="line number5 index4 alt2">
              5
            </div>
          </td>
          
          <td class="code">
            <div class="container">
              <div class="line number1 index0 alt2">
                `&lt;``android.support.v7.widget.RecyclerView`
              </div>
              
              <div class="line number2 index1 alt1">
                `        ``android:id``=``"@+id/rvToDoList"`
              </div>
              
              <div class="line number3 index2 alt2">
                `        ``android:layout_width``=``"match_parent"`
              </div>
              
              <div class="line number4 index3 alt1">
                `        ``android:layout_height``=``"match_parent"`
              </div>
              
              <div class="line number5 index4 alt2">
                `        ``app:layout_behavior``=``"@string/appbar_scrolling_view_behavior"``&gt;`
              </div>
            </div>
          </td>
        </tr>
      </table>
    </div>
  </div>
</div>



  AppBarLayout里面定义的view只要设置了app:layout_scrollFlags属性，就可以在RecyclerView滚动事件发生的时候被触发：当CoordinatorLayout发现RecyclerView中定义了这个属性，它会搜索自己所包含的其他view，看看是否有view与这个behavior相关联。AppBarLayout.ScrollingViewBehavior描述了RecyclerView与AppBarLayout之间的依赖关系。RecyclerView的任意滚动事件都将触发AppBarLayout或者AppBarLayout里面view的改变。



<div class="line number1 index0 alt2">
  <div>
    <div id="highlighter_195708" class="syntaxhighlighter  xml">
      <div class="toolbar">
        [?](http://my.oschina.net/kooeasy/blog/484593#)
      </div>
      
      <table border="0" cellspacing="0" cellpadding="0">
        <tr>
          <td class="gutter">
            <div class="line number1 index0 alt2">
              1
            </div>
            
            <div class="line number2 index1 alt1">
              2
            </div>
            
            <div class="line number3 index2 alt2">
              3
            </div>
            
            <div class="line number4 index3 alt1">
              4
            </div>
            
            <div class="line number5 index4 alt2">
              5
            </div>
            
            <div class="line number6 index5 alt1">
              6
            </div>
            
            <div class="line number7 index6 alt2">
              7
            </div>
            
            <div class="line number8 index7 alt1">
              8
            </div>
            
            <div class="line number9 index8 alt2">
              9
            </div>
            
            <div class="line number10 index9 alt1">
              10
            </div>
            
            <div class="line number11 index10 alt2">
              11
            </div>
            
            <div class="line number12 index11 alt1">
              12
            </div>
            
            <div class="line number13 index12 alt2">
              13
            </div>
          </td>
          
          <td class="code">
            <div class="container">
              <div class="line number1 index0 alt2">
                `&lt;``android.support.design.widget.AppBarLayout`
              </div>
              
              <div class="line number2 index1 alt1">
                `        ``android:layout_width``=``"match_parent"`
              </div>
              
              <div class="line number3 index2 alt2">
                `        ``android:layout_height``=``"wrap_content"`
              </div>
              
              <div class="line number4 index3 alt1">
                `        ``android:fitsSystemWindows``=``"true"`
              </div>
              
              <div class="line number5 index4 alt2">
                `        ``android:theme``=``"@style/ThemeOverlay.AppCompat.Dark.ActionBar"``&gt;`
              </div>
              
              <div class="line number6 index5 alt1">
                ` `
              </div>
              
              <div class="line number7 index6 alt2">
                `            ``&lt;``android.support.v7.widget.Toolbar`
              </div>
              
              <div class="line number8 index7 alt1">
                `                ``android:id``=``"@+id/toolbar"`
              </div>
              
              <div class="line number9 index8 alt2">
                `                ``android:layout_width``=``"match_parent"`
              </div>
              
              <div class="line number10 index9 alt1">
                `                ``android:layout_height``=``"?attr/actionBarSize"`
              </div>
              
              <div class="line number11 index10 alt2">
                `                ``app:layout_scrollFlags``=``"scroll|enterAlways"``/&gt;`
              </div>
              
              <div class="line number12 index11 alt1">
                ` `
              </div>
              
              <div class="line number13 index12 alt2">
                ` ``&lt;/``android.support.design.widget.AppBarLayout``&gt;`
              </div>
            </div>
          </td>
        </tr>
      </table>
    </div>
  </div>
  
  

    enterAlways: 一旦向上滚动这个view就可见。app:layout_scrollFlags属性里面必须至少启用scroll这个flag，这样这个view才会滚动出屏幕，否则它将一直固定在顶部。可以使用的其他flag有：
  

</div>


  - enterAlwaysCollapsed: 顾名思义，这个flag定义的是何时进入（已经消失之后何时再次显示）。假设你定义了一个最小高度（minHeight）同时enterAlways也定义了，那么view将在到达这个最小高度的时候开始显示，并且从这个时候开始慢慢展开，当滚动到顶部的时候展开完。
  
  - exitUntilCollapsed: 同样顾名思义，这个flag时定义何时退出，当你定义了一个minHeight，这个view将在滚动到达这个最小高度的时候消失。
  




  记住，要把带有scroll flag的view放在前面，这样收回的view才能让正常退出，而固定的view继续留在顶部。





  此时，你应该注意到我们的Toolbar能够响应滚动事件了。





  [![CoordinatorLayout与滚动的处理](http://static.oschina.net/uploads/img/201507/28112431_mOxz.gif)](http://static.oschina.net/uploads/img/201507/28112431_mOxz.gif)





  <a rel="nofollow">回到顶部</a>



### 制造折叠效果



  如果想制造toolbar的折叠效果，我们必须把Toolbar放在CollapsingToolbarLayout中：



<div class="line number1 index0 alt2">
  <div>
    <div id="highlighter_443633" class="syntaxhighlighter  xml">
      <div class="toolbar">
        [?](http://my.oschina.net/kooeasy/blog/484593#)
      </div>
      
      <table border="0" cellspacing="0" cellpadding="0">
        <tr>
          <td class="gutter">
            <div class="line number1 index0 alt2">
              1
            </div>
            
            <div class="line number2 index1 alt1">
              2
            </div>
            
            <div class="line number3 index2 alt2">
              3
            </div>
            
            <div class="line number4 index3 alt1">
              4
            </div>
            
            <div class="line number5 index4 alt2">
              5
            </div>
            
            <div class="line number6 index5 alt1">
              6
            </div>
            
            <div class="line number7 index6 alt2">
              7
            </div>
            
            <div class="line number8 index7 alt1">
              8
            </div>
            
            <div class="line number9 index8 alt2">
              9
            </div>
            
            <div class="line number10 index9 alt1">
              10
            </div>
            
            <div class="line number11 index10 alt2">
              11
            </div>
            
            <div class="line number12 index11 alt1">
              12
            </div>
            
            <div class="line number13 index12 alt2">
              13
            </div>
            
            <div class="line number14 index13 alt1">
              14
            </div>
            
            <div class="line number15 index14 alt2">
              15
            </div>
            
            <div class="line number16 index15 alt1">
              16
            </div>
          </td>
          
          <td class="code">
            <div class="container">
              <div class="line number1 index0 alt2">
                `&lt;``android.support.design.widget.CollapsingToolbarLayout`
              </div>
              
              <div class="line number2 index1 alt1">
                `            ``android:id``=``"@+id/collapsing_toolbar"`
              </div>
              
              <div class="line number3 index2 alt2">
                `            ``android:layout_width``=``"match_parent"`
              </div>
              
              <div class="line number4 index3 alt1">
                `            ``android:layout_height``=``"match_parent"`
              </div>
              
              <div class="line number5 index4 alt2">
                `            ``android:fitsSystemWindows``=``"true"`
              </div>
              
              <div class="line number6 index5 alt1">
                `            ``app:contentScrim``=``"?attr/colorPrimary"`
              </div>
              
              <div class="line number7 index6 alt2">
                `            ``app:expandedTitleMarginEnd``=``"64dp"`
              </div>
              
              <div class="line number8 index7 alt1">
                `            ``app:expandedTitleMarginStart``=``"48dp"`
              </div>
              
              <div class="line number9 index8 alt2">
                `            ``app:layout_scrollFlags``=``"scroll|exitUntilCollapsed"``&gt;`
              </div>
              
              <div class="line number10 index9 alt1">
                `             `
              </div>
              
              <div class="line number11 index10 alt2">
                `            ``&lt;``android.support.v7.widget.Toolbar`
              </div>
              
              <div class="line number12 index11 alt1">
                `                ``android:id``=``"@+id/toolbar"`
              </div>
              
              <div class="line number13 index12 alt2">
                `                ``android:layout_width``=``"match_parent"`
              </div>
              
              <div class="line number14 index13 alt1">
                `                ``android:layout_height``=``"?attr/actionBarSize"`
              </div>
              
              <div class="line number15 index14 alt2">
                `                ``app:layout_scrollFlags``=``"scroll|enterAlways"``&gt;&lt;/``android.support.v7.widget.Toolbar``&gt;`
              </div>
              
              <div class="line number16 index15 alt1">
                `        ``&lt;/``android.support.design.widget.CollapsingToolbarLayout``&gt;`
              </div>
            </div>
          </td>
        </tr>
      </table>
    </div>
  </div>
  
  

    [![CoordinatorLayout与滚动的处理](http://static.oschina.net/uploads/img/201507/28112431_oNXC.gif)](http://static.oschina.net/uploads/img/201507/28112431_oNXC.gif)
  

  
  

    现在效果就成了：
  

</div>



  通常，我们我们都是设置Toolbar的title，而现在，我们需要把title设置在CollapsingToolBarLayout上，而不是Toolbar。



<div class="line number1 index0 alt2">
  <div>
    <div id="highlighter_500348" class="syntaxhighlighter  java">
      <div class="toolbar">
        [?](http://my.oschina.net/kooeasy/blog/484593#)
      </div>
      
      <table border="0" cellspacing="0" cellpadding="0">
        <tr>
          <td class="gutter">
            <div class="line number1 index0 alt2">
              1
            </div>
            
            <div class="line number2 index1 alt1">
              2
            </div>
          </td>
          
          <td class="code">
            <div class="container">
              <div class="line number1 index0 alt2">
                `CollapsingToolbarLayout collapsingToolbar =(CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar);`
              </div>
              
              <div class="line number2 index1 alt1">
                `collapsingToolbar.setTitle(``"Title"``);`
              </div>
            </div>
          </td>
        </tr>
      </table>
    </div>
  </div>
</div>



  <a rel="nofollow">制造视差效果</a>





  <a rel="nofollow">回到顶部</a>





  CollapsingToolbarLayout还能让我们做出更高级的动画，比如在里面放一个ImageView，然后在它折叠的时候渐渐淡出。同时在用户滚动的时候title的高度也会随着改变。





  [![CoordinatorLayout与滚动的处理](http://static.oschina.net/uploads/img/201507/28112432_qzXu.gif)](http://static.oschina.net/uploads/img/201507/28112432_qzXu.gif)





  为了制造出这种效果，我们添加一个定义了app:layout_collapseMode=&#8221;parallax&#8221; 属性的ImageView。



## 

<div class="line number1 index0 alt2">
  <div>
    <div id="highlighter_174592" class="syntaxhighlighter  xml">
      <div class="toolbar">
        [?](http://my.oschina.net/kooeasy/blog/484593#)
      </div>
      
      <table border="0" cellspacing="0" cellpadding="0">
        <tr>
          <td class="gutter">
            <div class="line number1 index0 alt2">
              1
            </div>
            
            <div class="line number2 index1 alt1">
              2
            </div>
            
            <div class="line number3 index2 alt2">
              3
            </div>
            
            <div class="line number4 index3 alt1">
              4
            </div>
            
            <div class="line number5 index4 alt2">
              5
            </div>
            
            <div class="line number6 index5 alt1">
              6
            </div>
            
            <div class="line number7 index6 alt2">
              7
            </div>
            
            <div class="line number8 index7 alt1">
              8
            </div>
            
            <div class="line number9 index8 alt2">
              9
            </div>
            
            <div class="line number10 index9 alt1">
              10
            </div>
            
            <div class="line number11 index10 alt2">
              11
            </div>
            
            <div class="line number12 index11 alt1">
              12
            </div>
            
            <div class="line number13 index12 alt2">
              13
            </div>
            
            <div class="line number14 index13 alt1">
              14
            </div>
            
            <div class="line number15 index14 alt2">
              15
            </div>
            
            <div class="line number16 index15 alt1">
              16
            </div>
            
            <div class="line number17 index16 alt2">
              17
            </div>
            
            <div class="line number18 index17 alt1">
              18
            </div>
            
            <div class="line number19 index18 alt2">
              19
            </div>
            
            <div class="line number20 index19 alt1">
              20
            </div>
            
            <div class="line number21 index20 alt2">
              21
            </div>
            
            <div class="line number22 index21 alt1">
              22
            </div>
            
            <div class="line number23 index22 alt2">
              23
            </div>
            
            <div class="line number24 index23 alt1">
              24
            </div>
            
            <div class="line number25 index24 alt2">
              25
            </div>
          </td>
          
          <td class="code">
            <div class="container">
              <div class="line number1 index0 alt2">
                `  ``&lt;``android.support.design.widget.CollapsingToolbarLayout`
              </div>
              
              <div class="line number2 index1 alt1">
                `          ``android:id``=``"@+id/collapsing_toolbar"`
              </div>
              
              <div class="line number3 index2 alt2">
                `          ``android:layout_width``=``"match_parent"`
              </div>
              
              <div class="line number4 index3 alt1">
                `          ``android:layout_height``=``"match_parent"`
              </div>
              
              <div class="line number5 index4 alt2">
                `          ``android:fitsSystemWindows``=``"true"`
              </div>
              
              <div class="line number6 index5 alt1">
                `          ``app:contentScrim``=``"?attr/colorPrimary"`
              </div>
              
              <div class="line number7 index6 alt2">
                `          ``app:expandedTitleMarginEnd``=``"64dp"`
              </div>
              
              <div class="line number8 index7 alt1">
                `          ``app:expandedTitleMarginStart``=``"48dp"`
              </div>
              
              <div class="line number9 index8 alt2">
                `          ``app:layout_scrollFlags``=``"scroll|exitUntilCollapsed"``&gt;`
              </div>
              
              <div class="line number10 index9 alt1">
                ` `
              </div>
              
              <div class="line number11 index10 alt2">
                `          ``&lt;``android.support.v7.widget.Toolbar`
              </div>
              
              <div class="line number12 index11 alt1">
                `              ``android:id``=``"@+id/toolbar"`
              </div>
              
              <div class="line number13 index12 alt2">
                `              ``android:layout_width``=``"match_parent"`
              </div>
              
              <div class="line number14 index13 alt1">
                `              ``android:layout_height``=``"?attr/actionBarSize"`
              </div>
              
              <div class="line number15 index14 alt2">
                `              ``app:layout_scrollFlags``=``"scroll|enterAlways"``&gt;&lt;/``android.support.v7.widget.Toolbar``&gt;`
              </div>
              
              <div class="line number16 index15 alt1">
                `          ``&lt;``ImageView`
              </div>
              
              <div class="line number17 index16 alt2">
                `              ``android:src``=``"@drawable/cheese_1"`
              </div>
              
              <div class="line number18 index17 alt1">
                `              ``app:layout_scrollFlags``=``"scroll|enterAlways|enterAlwaysCollapsed"`
              </div>
              
              <div class="line number19 index18 alt2">
                `              ``android:layout_width``=``"wrap_content"`
              </div>
              
              <div class="line number20 index19 alt1">
                `              ``android:layout_height``=``"wrap_content"`
              </div>
              
              <div class="line number21 index20 alt2">
                `              ``android:scaleType``=``"centerCrop"`
              </div>
              
              <div class="line number22 index21 alt1">
                `              ``app:layout_collapseMode``=``"parallax"`
              </div>
              
              <div class="line number23 index22 alt2">
                `              ``android:minHeight``=``"100dp"``/&gt;`
              </div>
              
              <div class="line number24 index23 alt1">
                ` `
              </div>
              
              <div class="line number25 index24 alt2">
                `      ``&lt;/``android.support.design.widget.CollapsingToolbarLayout``&gt;`
              </div>
            </div>
          </td>
        </tr>
      </table>
    </div>
  </div>
</div>

## 在[CoordinatorLayout 与浮动操作按钮](http://guides.codepath.com/android/Floating-Action-Buttons#using-coordinatorlayout)中我们讨论了一个自定义behavior的例子。注： 译文[http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2015/0718/3197.html](http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2015/0718/3197.html)  。

## 自定义Behavior



  CoordinatorLayout的工作原理是搜索定义了[CoordinatorLayout Behavior](http://developer.android.com/reference/android/support/design/widget/CoordinatorLayout.Behavior.html) 的子view，不管是通过在xml中使用app:layout_behavior标签还是通过在代码中对view类使用@DefaultBehavior修饰符来添加注解。当滚动发生的时候，CoordinatorLayout会尝试触发那些声明了依赖的子view。





  要自己定义CoordinatorLayout Behavior，你需要实现layoutDependsOn() 和onDependentViewChanged()两个方法。比如AppBarLayout.Behavior 就定义了这两个关键方法。这个behavior用于当滚动发生的时候让AppBarLayout发生改变。



<div class="line number1 index0 alt2">
  <div>
    <div id="highlighter_14552" class="syntaxhighlighter  java">
      <div class="toolbar">
        [?](http://my.oschina.net/kooeasy/blog/484593#)
      </div>
      
      <table border="0" cellspacing="0" cellpadding="0">
        <tr>
          <td class="gutter">
            <div class="line number1 index0 alt2">
              1
            </div>
            
            <div class="line number2 index1 alt1">
              2
            </div>
            
            <div class="line number3 index2 alt2">
              3
            </div>
            
            <div class="line number4 index3 alt1">
              4
            </div>
            
            <div class="line number5 index4 alt2">
              5
            </div>
            
            <div class="line number6 index5 alt1">
              6
            </div>
            
            <div class="line number7 index6 alt2">
              7
            </div>
            
            <div class="line number8 index7 alt1">
              8
            </div>
            
            <div class="line number9 index8 alt2">
              9
            </div>
            
            <div class="line number10 index9 alt1">
              10
            </div>
            
            <div class="line number11 index10 alt2">
              11
            </div>
          </td>
          
          <td class="code">
            <div class="container">
              <div class="line number1 index0 alt2">
                `public` `boolean` `layoutDependsOn(CoordinatorLayout parent, View child, View dependency) {`
              </div>
              
              <div class="line number2 index1 alt1">
                `    ``return` `dependency ``instanceof` `AppBarLayout;`
              </div>
              
              <div class="line number3 index2 alt2">
                `}`
              </div>
              
              <div class="line number4 index3 alt1">
                ` `
              </div>
              
              <div class="line number5 index4 alt2">
                `public` `boolean` `onDependentViewChanged(CoordinatorLayout parent, View child, View dependency) {`
              </div>
              
              <div class="line number6 index5 alt1">
                `    ``// check the behavior triggered`
              </div>
              
              <div class="line number7 index6 alt2">
                `    ``android.support.design.widget.CoordinatorLayout.Behavior behavior = ((android.support.design.widget.CoordinatorLayout.LayoutParams) dependency.getLayoutParams()).getBehavior();`
              </div>
              
              <div class="line number8 index7 alt1">
                `    ``if` `(behavior ``instanceof` `AppBarLayout.Behavior) {`
              </div>
              
              <div class="line number9 index8 alt2">
                `        ``// do stuff here`
              </div>
              
              <div class="line number10 index9 alt1">
                `    ``}`
              </div>
              
              <div class="line number11 index10 alt2">
                `}`
              </div>
            </div>
          </td>
        </tr>
      </table>
    </div>
  </div>
</div>



  理解如何实现这些自定义behavior的最好途径是研究AppBarLayout.Behavior 和 FloatingActionButtion.Behavior。虽然这些源代码还没有放出来，但是你可以使用Android Studio 1.2集成的反编译器来查看。





  参考：[Android的材料设计兼容库（Design Support Library）](http://www.jcodecraeer.com/a/anzhuokaifa/developer/2015/0531/2958.html)

概览#

设置#

浮动操作按钮与Snackbar#

#

Toolbar的扩展与收缩#

💬 评论

概览

设置

浮动操作按钮与Snackbar

Toolbar的扩展与收缩