从服务发送数据到活动Android

Question

我正在构建使用服务进行播放的音乐播放器。我有一个活动用户界面，可以控制（播放，暂停，接下来，...）服务。 我想在按下下一个或上一个按钮时从我的服务更新UI。我想传递一个整数值。这里是我的代码：

我已经使用信使进行沟通。在我服务的代码如下所示：

enum Event { 
    NextSongChanged, CurrentPlayingSong 
}; 

public synchronized void registerHandler(Messenger m) { 
    clients.add(m); 
} 


private void emit(Event e) { 
    for (Messenger m : clients) { 
     try { 
      m.send(Message.obtain(null, e.ordinal())); 
     } catch (RemoteException exception) { 
      /* The client must've died */ 
      clients.remove(m); 
     } 
    } 
} 

我的方法，我的下一个按钮的点击呼叫：

public synchronized void playnext() { 
    reset(); 
    if(songIndex < (songsList.size() - 1)) { 
     songIndex += 1; 
     playSong(songIndex); 
    } else { 
     songIndex = 0; 
     playSong(songIndex); 
    } 
    emit(Event.NextSongChanged); 
} 

只要我火了NextSongChanged事件我想通过“songIndex”变成我的活动。任何想法如何实现这一目标？

我的动态代码来处理事件：

private Messenger playerMessenger = new Messenger(new Handler() { 
    @Override 
    public void handleMessage(Message msg) { 
     switch (MyService.Event.values()[msg.what]) { 
      case NextSongChanged: 
       //String songTitle = songsList.get(currentSongIndex+1).get("songTitle"); 
       //currentSongIndex += 1; 
       //songTitleLabel.setText(songTitle); 
       //updatePlaying(); 
       break; 

      case CurrentPlayingSong: 
       break; 
     } 
    } 
}); 

Answer 1

示例代码，希望可以帮助别人

集处理器（接收消息）和Messenger（沟通）MainActivity.java

Messenger msgService; 
boolean isBound; 

ServiceConnection connection = new ServiceConnection() { 

    @Override 
    public void onServiceDisconnected(ComponentName name) { isBound = false; } 

    @Override 
    public void onServiceConnected(ComponentName name, IBinder service) { 
     isBound = true; 
     msgService = new Messenger(service); 
    } 
}; 

public void sendMessage(View view) { 
    if (isBound) { 
     try { 
      Message message = Message.obtain(null, MessangerService.MESSAGE, 1, 1); 
      message.replyTo = replyMessenger; 

      Bundle bundle = new Bundle(); 
      bundle.putString("rec", "Hi, you hear me"); 
      message.setData(bundle); 

      msgService.send(message); //sending message to service 

     } catch (RemoteException e) { 
      e.printStackTrace(); 
     } 
    } 
} 
//setting reply messenger and handler 
Messenger replyMessenger = new Messenger(new HandlerReplyMsg()); 

class HandlerReplyMsg extends Handler { 
    @Override 
    public void handleMessage(Message msg) { 
     super.handleMessage(msg); 
     String recdMessage = msg.obj.toString(); //msg received from service 
     toast(recdMessage); 
    } 
} 

2.设置服务等级MessengerService.java

Messenger replyMessanger; 
final static int MESSAGE = 1; 

class IncomingHandler extends Handler { 

    @Override 
    public void handleMessage(Message msg) { 

     if (msg.what == MESSAGE) { 
      Bundle bundle = msg.getData(); 
      toast(bundle.getString("rec"));//message received 
      replyMessanger = msg.replyTo; //init reply messenger 
      doSomething(); 
     } 
    } 
} 

private void doSomething() { 
    // do stuff 

    if (replyMessanger != null) 
     try { 
      Message message = new Message(); 
      message.obj = "Yes loud and clear"; 
      replyMessanger.send(message);//replying/sending msg to activity 
     } catch (RemoteException e) { 
      e.printStackTrace(); 
     } 
} 
Messenger messenger = new Messenger(new IncomingHandler()); 

@Override 
public IBinder onBind(Intent intent) { 
    return messenger.getBinder(); 
} 

确保在manifest申报服务和binding/unbinding服务活动。