当启动Activity时保留导航

> 编写:[fastcome1985](https://github.com/fastcome1985) - 原文:[http://developer.android.com/training/notify-user/navigation.html](http://developer.android.com/training/notify-user/navigation.html) 部分设计一个notification的目的是为了保持用户的导航体验。为了详细讨论这个课题，请看 [Notifications](#) API引导，分为下列两种主要情况： ~~~ * 常规的activity 你启动的是你application工作流中的一部分[Activity](developer.android.com/reference/android/app/Activity.html)。 * 特定的activity 用户只能从notification中启动，才能看到这个[Activity](http://developer.android.com/intl/zh-cn/reference/android/app/Activity.html)，在某种意义上，这个[Activity](http://developer.android.com/intl/zh-cn/reference/android/app/Activity.html)是notification的扩展，额外展示了一些notification本身难以展示的信息。 ~~~ ### 设置一个常规的[Activity](# "An activity represents a single screen with a user interface.") PendingIntent 设置一个直接启动的入口[Activity](# "An activity represents a single screen with a user interface.")的PendingIntent，遵循以下步骤： 1 在manifest中定义你application的[Activity](# "An activity represents a single screen with a user interface.")层次，最终的manifest文件应该像这个： ~~~ <activity android:name=".MainActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name=".ResultActivity" android:parentActivityName=".MainActivity"> <meta-data android:name="android.support.PARENT_ACTIVITY" android:value=".MainActivity"/> </activity> ~~~ 2 在基于启动[Activity](# "An activity represents a single screen with a user interface.")的[Intent](#)中创建一个返回栈，比如： ~~~ int id = 1; ... Intent resultIntent = new Intent(this, ResultActivity.class); TaskStackBuilder stackBuilder = TaskStackBuilder.create(this); // Adds the back stack stackBuilder.addParentStack(ResultActivity.class); // Adds the Intent to the top of the stack stackBuilder.addNextIntent(resultIntent); // Gets a PendingIntent containing the entire back stack PendingIntent resultPendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT); ... NotificationCompat.Builder builder = new NotificationCompat.Builder(this); builder.setContentIntent(resultPendingIntent); NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE); mNotificationManager.notify(id, builder.build()); ~~~ ### 设置一个特定的[Activity](# "An activity represents a single screen with a user interface.") PendingIntent 一个特定的[Activity](# "An activity represents a single screen with a user interface.")不需要一个返回栈，所以你不需要在manifest中定义[Activity](# "An activity represents a single screen with a user interface.")的层次，以及你不需要调用 [addParentStack()](#))方法去构建一个返回栈。作为代替，你需要用manifest设置[Activity](# "An activity represents a single screen with a user interface.")任务选项，以及调用 [getActivity()](#))创建[PendingIntent](#) 1. manifest中，在[Activity](# "An activity represents a single screen with a user interface.")的 [](#) 标签中增加下列属性：[android:name="activityclass"](#)[activity](# "An activity represents a single screen with a user interface.")的完整的类名。[android:taskAffinity=""](#)结合你在代码里设置的[FLAG_ACTIVITY_NEW_TASK](#)标识， 确保这个[Activity](# "An activity represents a single screen with a user interface.")不会进入application的默认任务。任何与 application的默认任务有密切关系的任务都不会受到影响。[android:excludeFromRecents="true"](#)将新任务从最近列表中排除，目的是为了防止用户不小心返回到它。 1. 建立以及发布notification：a.创建一个启动[Activity](# "An activity represents a single screen with a user interface.")的[Intent](#).b.通过调用[setFlags()](#))方法并设置标识[FLAG_ACTIVITY_NEW_TASK](#) 与 [FLAG_ACTIVITY_CLEAR_TASK](#)，来设置[Activity](# "An activity represents a single screen with a user interface.")在一个新的，空的任务中启动。c.在[Intent](#)中设置其他你需要的选项。d.通过调用 [getActivity()](http://developer.android.com/intl/zh-cn/reference/android/app/PendingIntent.html#getActivity%28android.content.Context,%20int,%20android.content.Intent,%20int%29)方法从[Intent](#)中创建一个 [PendingIntent](#)，你可以把这个[PendingIntent](#) 当做 [setContentIntent()](http://developer.android.com/intl/zh-cn/reference/android/support/v4/app/NotificationCompat.Builder.html#setContentIntent%28android.app.PendingIntent%29)的参数来使用。下面的代码片段演示了这个过程： ~~~ // Instantiate a Builder object. NotificationCompat.Builder builder = new NotificationCompat.Builder(this); // Creates an Intent for the Activity Intent notifyIntent = new Intent(new ComponentName(this, ResultActivity.class)); // Sets the Activity to start in a new, empty task notifyIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK); // Creates the PendingIntent PendingIntent notifyIntent = PendingIntent.getActivity( this, 0, notifyIntent, PendingIntent.FLAG_UPDATE_CURRENT ); // Puts the PendingIntent into the notification builder builder.setContentIntent(notifyIntent); // Notifications are issued by sending them to the // NotificationManager system service. NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE); // Builds an anonymous Notification object from the builder, and // passes it to the NotificationManager mNotificationManager.notify(id, builder.build()); ~~~