无法从 Android AppWidgetProvider 启动 ActivityManager.RunningTaskInfo.topActivity

Question

我有 MyAppWidgetProvider 类的 onUpdate(...) 方法和代码：

...
Intent launchAppIntent = new Intent(context, SearchActivity.class);        
PendingIntent launchAppPendingIntent = PendingIntent.getActivity(context, 0, launchAppIntent, 0);        
remoteView.setOnClickPendingIntent(R.id.logo, launchAppPendingIntent);  
...

它工作正常。新的 SearchActivity 通过单击小部件启动。现在，我想开始单击而不是 SearchActivity，而是单击任务堆栈顶部的活动。为此，我将上面的代码更改为：

ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningTaskInfo> tasks = am.getRunningTasks(30);        
for (ActivityManager.RunningTaskInfo task:tasks) {
    if (task.baseActivity.getShortClassName().equals(".MainActivity")) {    
        try {
            Intent launchAppIntent = new Intent(context, Class.forName(task.topActivity.getClassName()));
            PendingIntent launchAppPendingIntent = PendingIntent.getActivity(context, 0, launchAppIntent, 0);        
            remoteView.setOnClickPendingIntent(R.id.logo, launchAppPendingIntent);                     
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(CashWidgetProvider.class.getName()).log(Level.SEVERE, null, ex);
        }                  
    }
}

这不起作用。任务堆栈中的前台活动不会出现在监视器上。此外，我在运行此代码的日志中没有收到任何消息。

但是，相同的代码可以很好地放置在从 Activity 继承的类的某些方法中。

ActivityManager am = (ActivityManager) this.getSystemService(ACTIVITY_SERVICE);
List<ActivityManager.RunningTaskInfo> tasks = am.getRunningTasks(30);        
for (ActivityManager.RunningTaskInfo task:tasks) {
    System.out.println(task.baseActivity.getShortClassName());
    if (task.baseActivity.getShortClassName().equals(".MainActivity")) {
        try {
            Intent launchAppIntent = new Intent(this, Class.forName(task.topActivity.getClassName())); 
            startActivity(launchAppIntent);
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(AbstractActivity.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
} 

我怎样才能让它在 AppWidget 上工作！？

Answer 1

像往常一样，问题的出现是由于对小部件生命周期的误解......为了使其正常工作，我必须创建从 Service 继承的 MyService 类，并使用代码覆盖 onStart 方法：

...
Context context = this.getApplicationContext();
ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningTaskInfo> tasks = am.getRunningTasks(30);        
for (ActivityManager.RunningTaskInfo task:tasks) {
    if (task.baseActivity.getShortClassName().equals(".MainActivity")) {    
        try {
            Intent launchTopIntent = new Intent(context, Class.forName(task.topActivity.getClassName()));
                context.startActivity(launchTopIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK));             
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(CashWidgetProvider.class.getName()).log(Level.SEVERE, null, ex);
        }                  
    }
} 
...

并通过代码从 AppWidgetProvider 类调用上面的 MyService

Intent launchAppIntent = new Intent(context, MyService.class);
launchAppIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, appWidgetIds);
PendingIntent launchAppPendingIntent = PendingIntent.getService(
            context.getApplicationContext(), 0, launchAppIntent, PendingIntent.FLAG_UPDATE_CURRENT);
remoteView.setOnClickPendingIntent(R.id.logo, launchAppPendingIntent2); 

： 部分下添加此新服务。

<application>
    ...
    <service android:name=".MyService"/>
</application>

忘记在 AndroidManifest.xml 中的P.S. 也许，使用 BroadcastReceiver 而不是 Service 会更好。