是时候来了解android7了:多窗口支持

转载于 http://blog.csdn.net/qibin0506/article/details/52270674

这篇文章开始, 我们来了解一下android 7的一些新特性, 话说今年android 7预览版本来的比以往都稍早一些, 这样对于我们开发者来说算是一个好消息, 我们可以有充足的时间来看新版android的一些特性, 让我们的应用更快的支持到android 7. 前段时间android 7发送了最终预览版本, 这也表示现在的sdk已经是最终的sdk了, 所以我们从现在开始, 完全可以让应用支持到android 7了.

今天的这篇文章我们来介绍一下在android 7上最为直观的一个特性-多窗口支持, 当然也可以叫他分屏模式. 有了这个特性妈妈再也不用担心我应用间切换的烦恼了, 那什么多窗口模式呢? 其实在很多国产机器上早就已经支持多窗口了, 只不过这次android 7标准化了多窗口模式, 这对我们开发者来说, 可以算是天大的好消息. 废话那么说, 我们还没看到多窗口模式什么样呢? 下面一张图来体验一下.

让我们的应用支持多窗口模式

如何让我们的应用支持多窗口模式呢? 其实android 7是默认开启多窗口模式的, 不过如果你用低于android 7的sdk构建的应用, 会在多窗口模式下发出一个警告. 那如何让我们的应用禁用多窗口模式呢? 毕竟好多人还是不喜欢让自己的应用和别人分享屏幕的(比如QQ), 这个也很简单, 只需要在清单文件的application或者activity中添加android:resizeableActivity="false"就ok了(目测, 接下来大多数国产APP中都会有这条属性).

多窗口模式的一些配置

禁用归禁用, 但是对于我们开发者来说, 还是要继续了解一下多窗口模式的, 那接下来我们来看一下, 在多窗口模式中又会多哪些属性. 在清单文件中我们配置activity的地方, 又多了一个layout节点, 这个节点的属性不多, 主要是用来配置多窗口模式下的一些属性的. 下面我们首先来看看如何配置, 然后来说说都是什么作用:

<code class="language-xml hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">activity</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">".MyActivity"</span>></span>    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">layout</span>          <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:defaultHeight</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"500dp"</span>          <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:defaultWidth</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"500dp"</span>          <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:gravity</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"bottom|end"</span>          <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:minimalHeight</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"200dp"</span>          <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:minimalWidth</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"200dp"</span> /></span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">activity</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>

很简单,就是多了一个layout节点, 我们来看看他的属性.

1. android:defaultHeight 这条是配置多窗口模式下默认的高度.
2. android:defaultWidth 这条是配置多窗口模式下默认的宽度.
3. android:gravity 这条是配置多窗口模式下activity的初始位置. (注意:这条语句在我测试过程中发现貌似没起到作用)
4. android:minimalHeight 这条是配置多窗口模式下最小的高度. (注意:这条语句在我测试过程中发现配置后直接编译不了)
5. android:minimalWidth 这条是配置多窗口模式下最小的宽度. (注意:这条语句在我测试过程中发现配置后直接编译不了)

其实, 就算我们的应用要支持多窗口模式, 上面的layout节点我们也是完全可以忽略的(而且我感觉大部分情况下是要忽略的)

还是看看生命周期

其实, 多窗口本身还是很简单的, 我们最关心的还是activity在多窗口模式下的生命周期, 下面我们就用一段demo来看一下在多窗口模式下activity的生命周期.

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onCreate</span>(Bundle savedInstanceState) {    prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"onCreate"</span>);}<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onStart</span>() {    prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"onStart"</span>);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onStart();}<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onResume</span>() {    prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"onResume"</span>);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onResume();}<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onPause</span>() {    prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"onPause"</span>);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onPause();}<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onStop</span>() {    prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"onStop"</span>);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onStop();}<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onDestroy</span>() {    prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"onDestory"</span>);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onDestroy();}<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onSaveInstanceState</span>(Bundle outState) {    prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"onSaveInstanceState"</span>);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onSaveInstanceState(outState);}<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onRestoreInstanceState</span>(Bundle savedInstanceState) {    prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"onRestoreInstanceState"</span>);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onRestoreInstanceState(savedInstanceState);}<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onMultiWindowModeChanged</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> isInMultiWindowMode) {    prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"onMultiWindowModeChanged:"</span> + isInMultiWindowMode);    prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"isInMultiWindowMode:"</span> + isInMultiWindowMode());    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onMultiWindowModeChanged(isInMultiWindowMode);}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">prntLog</span>(String log) {    Log.d(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"MainActivity"</span>, log);}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li></ul>

在开始之前, 我们发现有一个回调onMultiWindowModeChanged是我们不太熟悉的, 这个回调是为了多窗口模式新增的一个, 在进入或者退出多窗口模式, 这个回调会执行, 而且, 我们还可以用过isInMultiWindowMode()方法来判断当前activity是否在多窗口模式下. 接下来, 我们来演示一下生命周期吧.

首先是进入多窗口模式(进入多窗口模式的方法是长按手机上的overview键)

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">D/MainActivity: onMultiWindowModeChanged:<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>D/MainActivity: isInMultiWindowMode:<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>D/MainActivity: onPauseD/MainActivity: onSaveInstanceStateD/MainActivity: onStopD/MainActivity: onDestoryD/MainActivity: onCreateD/MainActivity: onStartD/MainActivity: onRestoreInstanceStateD/MainActivity: onResumeD/MainActivity: onPause</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul>

从log中可以发现, 在进入多窗口模式时, 首先回调的是onMultiWindowModeChanged方法, 然后很令人沮丧的是我们的activity销毁了,并且调用了onSaveInstanceState方法, 然后activit启动, 其实就是我们activity重启了.

那退出多窗口模式呢?

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">D/MainActivity: onSaveInstanceStateD/MainActivity: onStopD/MainActivity: onDestoryD/MainActivity: onCreateD/MainActivity: onStartD/MainActivity: onRestoreInstanceStateD/MainActivity: onResumeD/MainActivity: onPauseD/MainActivity: onMultiWindowModeChanged:<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>D/MainActivity: isInMultiWindowMode:<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">false</span>D/MainActivity: onResume</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul>

首先是一个配置变化销毁的过程, 然后是一个恢复的过程, 并且回调了onMultiWindowModeChanged方法, 此时的isInMultiWindowMode是false.

继续看生命周期, 如果我们的焦点从一个activity中切换到了和它同处于多窗口模式下的另外一个activity呢?

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">D/MainActivity: onPauseD/SecondActivity: onResume</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>

此时当前activity会暂停, 新获取角度的activity回调onResume, 在这里官网还有一个notice, 比如我们之前是在onPause中暂停视频播放, 在这种情况下, 失去焦点后就暂停了, 显然这不是很好的用户体验, 我们需要把视频的暂停和继续放到onStop和onStart中.

启动activity

现在我们在来学习下如何在多窗口模式下启动activity. 这样分两种情况了, 一种在是当前栈中启动, 另一种是在新的栈中启动. 
对于第一种情况, 很简单, 就是在当前窗口中启动新的activity, 而第二种情况, 我们可以指定在同级窗口下启动, 只需要给intent设置一个FLAG_ACTIVITY_LAUNCH_ADJACENTflag就ok. 
例如下面的代码:

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">Intent intent = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Intent(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>, SecondActivity.class);intent.setFlags(Intent.FLAG_ACTIVITY_LAUNCH_ADJACENT|Intent.FLAG_ACTIVITY_NEW_TASK);startActivity(intent);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

上面的代码我们会在另外一个窗口启动新的activity

另外, 我们还可以制定新启动的activity的大小.

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">Rect bounds = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Rect(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">500</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">300</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>);ActivityOptions options = ActivityOptions.makeBasic();options.setLaunchBounds(bounds);Intent intent = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Intent(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>, SecondActivity.class);intent.setFlags(Intent.FLAG_ACTIVITY_LAUNCH_ADJACENT|Intent.FLAG_ACTIVITY_NEW_TASK);ActivityCompat.startActivity(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>, intent, options.toBundle());</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul>

跨activity拖拽

从android 4.0开始, android就已经支持activity内的内容拖拽了, 现在在多窗口模式下, android增强了拖拽功能, 另它在多窗口模式下可以在activity间实现内容的拖拽, 不过在activity间也仅限于内容的拖拽, 对view的跨activity拖拽还是不可以的. 现在我们在MainActivity和SecondActivity之前来模拟一下跨activity拖拽内容.

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// MainActivity</span>Button view = (Button) findViewById(R.id.button);view.setOnLongClickListener(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> View.OnLongClickListener() {    <span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="box-sizing: border-box;">onLongClick</span>(View view) {        ClipData data = ClipData.newPlainText(view.getClass().getName(),                ((Button) view).getText());        View.DragShadowBuilder builder = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> View.DragShadowBuilder(view);        view.startDragAndDrop(data, builder, view, View.DRAG_FLAG_GLOBAL);        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;    }});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

这里我们监听button的长按事件, 在长按事件中, 首先我们用button的文本构建一个ClipData对象. 然后调用view.startDragAndDrop方法来启动拖拽. 这里要注意一下最后一个参数View.DRAG_FLAG_GLOBAL, 这个flag表示我们可以跨activity进行拖拽.

接着我们来看看SecondActivity如何处理拖拽事件.

<code class="language-java hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> TextView content = (TextView) findViewById(R.id.content);findViewById(R.id.container).setOnDragListener(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> View.OnDragListener() {<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> <span class="hljs-title" style="box-sizing: border-box;">onDrag</span>(View view, DragEvent dragEvent) {    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">switch</span> (dragEvent.getAction()) {        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> DragEvent.ACTION_DRAG_STARTED:            prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"drag started"</span>);            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">break</span>;        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> DragEvent.ACTION_DRAG_ENTERED:            prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"drag entered"</span>);            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">break</span>;        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> DragEvent.ACTION_DROP:            ClipData.Item item = dragEvent.getClipData().getItemAt(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>);            content.setText(item.getText());            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">break</span>;        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> DragEvent.ACTION_DRAG_ENDED:            prntLog(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"drag entered"</span>);            <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">break</span>;    }    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>;}});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li></ul>

这里首先我们拿到根布局(这里就先不要纠结根布局到底是谁了, 这里的根布局指的是content_view的根布局), 然后给它设置OnDragListener的监听, 在ACTION_DROP时候我们通过dragEvent.getClipData().getItemAt(0)拿到拖拽的item, 然后通过getText()方法获取到内容, 并且设置到TextView上显示. 
来看看效果:

ok, 到现在为止android 7的多窗口模式我们就介绍完了, 这些内容大家有点印象就可以, 毕竟在我们日常的工作中基本一个android:resizeableActivity="false"就可以了.