TaskStackBuilder

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

实现方式一:

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);}

实现方式二:

实现上述需求，采用TaskStackBuilder方法
1.在AndroidManifest.xml配置Activity关系

<activity android:name=".MessageActivity"          android:parentActivityName=".MainActivity"/>

2.代码

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);}

总结:

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。