Android 知识点——TaskStackBuilder

   <p>积跬步，以至千里；积小流，以成江海。</p>    <p>场景：当应用处于后台时，默认情况下，从通知启动一个Activity，按返回键会回到主屏幕。但遇到这样的需求，按返回键时仍然留在当前应用。类似于微信、QQ等点击通知栏，显示Chat页，点击返回会回到主Activity。</p>    <h2>一</h2>    <p>在MainActivity点击按钮开启一个服务，并将Activity退出。服务中子线程睡眠3秒后，模拟弹出通知。点击通知栏，进入消息列表页后。点击返回按钮时，可见直接回到了桌面。并没有回到自己主页面的。</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/b3133e553a7e5878642685d8e651cdc4.gif"></p>    <p>默认形式</p>    <p>代码片段：</p>    <pre>  <code class="language-java">private void showNotification() {      NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);        Intent msgIntent = new Intent();      msgIntent.setClass(this, MessageActivity.class);        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, msgIntent, PendingIntent.FLAG_UPDATE_CURRENT);        // create and send notificaiton      NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this)              .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))              .setSmallIcon(getApplicationInfo().icon)              .setWhen(System.currentTimeMillis())              .setAutoCancel(true)//自己维护通知的消失              .setContentTitle("我是标题")              .setTicker("我是ticker")              .setContentText("我是内容")              .setContentIntent(pendingIntent);      //将一个Notification变成悬挂式Notification      mBuilder.setFullScreenIntent(pendingIntent, true);      Notification notification = mBuilder.build();      manager.notify(0, notification);  }</code></pre>    <h2>二</h2>    <p>实现上述需求，采用PendingIntent.getActivities()方法</p>    <p>代码片段：</p>    <pre>  <code class="language-java">private void showNotification() {      NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);        Intent msgIntent = new Intent();      Intent mainIntent = new Intent();      msgIntent.setClass(this, MessageActivity.class);      mainIntent.setClass(this, MainActivity.class);      //注意此处的顺序      Intent[] intents = new Intent[]{mainIntent, msgIntent};      PendingIntent pendingIntent = PendingIntent.              getActivities(this, 0, intents, PendingIntent.FLAG_UPDATE_CURRENT);        // create and send notificaiton      NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this)              .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))              .setSmallIcon(getApplicationInfo().icon)              .setWhen(System.currentTimeMillis())              .setAutoCancel(true)//自己维护通知的消失              .setContentTitle("我是标题")              .setTicker("我是ticker")              .setContentText("我是内容")              .setContentIntent(pendingIntent);      //将一个Notification变成悬挂式Notification      mBuilder.setFullScreenIntent(pendingIntent, true);      Notification notification = mBuilder.build();      manager.notify(0, notification);  }</code></pre>    <p style="text-align:center"><img src="https://simg.open-open.com/show/9f4e5cc8067d927f1de71600ecbcfef2.gif"></p>    <p>点击返回，回到主界面</p>    <h2>三</h2>    <p>实现上述需求，采用TaskStackBuilder方法</p>    <p>1.在AndroidManifest.xml配置Activity关系</p>    <pre>  <code class="language-java"><activity android:name=".MessageActivity"            android:parentActivityName=".MainActivity"/></code></pre>    <p>2.代码</p>    <pre>  <code class="language-java">private void showNotification() {      NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);      //启动通知Activity时，拉起主页面Activity      Intent msgIntent = new Intent();      msgIntent.setClass(this, MessageActivity.class);        //创建返回栈      TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);      //添加Activity到返回栈      stackBuilder.addParentStack(MessageActivity.class);      //添加Intent到栈顶      stackBuilder.addNextIntent(msgIntent);        PendingIntent pendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);        // create and send notificaiton      NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this)              .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))              .setSmallIcon(getApplicationInfo().icon)              .setWhen(System.currentTimeMillis())              .setAutoCancel(true)//自己维护通知的消失              .setContentTitle("我是标题")              .setTicker("我是ticker")              .setContentText("我是内容")              .setContentIntent(pendingIntent);      //将一个Notification变成悬挂式Notification      mBuilder.setFullScreenIntent(pendingIntent, true);      Notification notification = mBuilder.build();      manager.notify(0, notification);  }</code></pre>    <h2>小结：</h2>    <p>第二种方式适合项目在一个module中开发的情况。如果是组件化开发，通知页面MessageActivity在其他module中，则是无法引用到MainActivity的。因此采用第三种方式更合适。只需要在app的清单文件中再次配置一下Activity的关系即可。打包的时候会合并清单文件配置。</p>    <p> </p>    <p>来自：http://www.jianshu.com/p/678e2322fd41</p>    <p> </p>