我应该如何（应该）向服务中的线程添加处理程序

Question

我仍在处理Pro Android 2的简短服务示例（页码304）同样，服务示例由两个类组成：显示的BackgroundService.java如下所示和MainActivity.java。现在我想扩展这段代码，将数据传递给我的应用程序中的另一个活动。从我了解到我添加了一个处理程序的开始下面的代码：

public class MainActivity extends Activity { 
     private static final String TAG = "MainActivity"; 

     @Override 
     public void onCreate(Bundle savedInstanceState) 
     { 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.main); 

      Log.d(TAG, "starting service"); 

      Button bindBtn = (Button)findViewById(R.id.bindBtn); 
      bindBtn.setOnClickListener(new OnClickListener() { 

       @Override 
       public void onClick(View arg0) { 
        Intent backgroundService = new Intent(MainActivity.this, com.marie.mainactivity.BackgroundService.class); 
        startService(backgroundService); 
       } 
      }); 

      Button unbindBtn = (Button)findViewById(R.id.unbindBtn); 
      unbindBtn.setOnClickListener(new OnClickListener() { 
       @Override 
       public void onClick(View arg0) { 
        stopService(new Intent(MainActivity.this, BackgroundService.class)); 
       } 
      }); 
     } 
    } 

    // The handler code I added 
    // I'm not sure what fills out the msg.what field for the switch 
    private Handler messageHandler = new Handler() { 

     @Override 
     public void handleMessage(Message msg) { 
      switch(msg.what) { 
       //handle update 
       //possibly update another activity??? 
      } 
     } 

    }; 

    public class BackgroundService extends Service { 
     private NotificationManager notificationMgr; 

     @Override 
     public void onCreate() { 
      super.onCreate(); 

      notificationMgr = NotificationManager)getSystemService(NOTIFICATION_SERVICE); 

      displayNotificationMessage("starting Background Service"); 

      Thread thr = new Thread(null, new ServiceWorker(), "BackgroundService"); 
      thr.start(); 
     } 

     class ServiceWorker implements Runnable 
     { 
      public void run() { 
       mResult = doSomethingTimeConsuming(); 

       //Use the handler to send update to the main thread or another activity??? 
       messageHandler.sendMessage(Message.obtain(messageHandler, mResults)); 

       BackgroundService.this.stopSelf(); 
      } 
     } 

     @Override 
     public void onDestroy() 
     { 
      displayNotificationMessage("stopping Background Service"); 
      super.onDestroy(); 
     } 

     @Override 
     public void onStart(Intent intent, int startId) { 
      super.onStart(intent, startId); 
     } 

     @Override 
     public IBinder onBind(Intent intent) { 
      return null; 
     } 

     private void displayNotificationMessage(String message) 
     { 
      Notification notification = new Notification(R.drawable.note, message, System.currentTimeMillis()); 

      PendingIntent contentIntent = PendingIntent.getActivity(this, 0, new Intent(this, MainActivity.class), 0); 

      notification.setLatestEventInfo(this, "Background Service", message, contentIntent); 

      notificationMgr.notify(R.id.app_notification_id, notification); 
     } 
    } 

我已经学会了，当我得到的服务实例，我可以通过它的处理程序。但我不知道该怎么做。

Answer 1

如果要将服务中的信息发送到活动，请使用广播接收器。为您的活动制作一类广播接收器内部类，以便它可以访问活动数据。通过意向

IntentFilter filter = new IntentFilter("com.damluar.intent.action.NEWTWEETS"); 
broadcastReceiver = new NewTweetsReceiver(); 
registerReceiver(broadcastReceiver, filter); 

然后从服务，您可以将数据发送到广播（和外活动）：然后注册广播

sendBroadcast(new Intent("com.damluar.intent.action.NEWTWEETS")); 

Answer 2

你可以定义一个setHandler(Handler handler) setter函数在BackgroundSerivce类并调用它在启动服务之前从您的MainActivity开始，并以此方式传递处理程序。