Messenger是一种实现跨进程通信的方法。是一种轻量级的IPC发难，底层实现是AIDL。

Messenger的构造方法

public Messenger(Handler target){ mTarget =target.getImessenger(); } public Messenger(IBinder target){ mTarget = IMessenger.Stub.asInterface(target); }

有以上代码可看出Messenger对AIDL做了封装。

Messenger实现

通过Messenger实现在Service与Acitivity之间的通信。

服务端代码

package com.treeanimals.max.tecent; import android.app.Service; import android.content.Intent; import android.os.Bundle; import android.os.Handler; import android.os.IBinder; import android.os.Message; import android.os.Messenger; import android.os.RemoteException; import android.support.annotation.Nullable; import android.util.Log; /** * Created by 95112 on 8/30/2017. */ public class MessengerService extends Service { private static final String TAG = "MessengerService"; private static class MessengerHandler extends Handler { @Override public void handleMessage(Message msg) { switch (msg.what){ case 1: Log.d(TAG,msg.getData().getString("msg")); Messenger client = msg.replyTo; Message replyMessage = Message.obtain(null,2); Bundle bundle = new Bundle(); bundle.putString("reply","回复"); replyMessage.setData(bundle); try { client.send(replyMessage); } catch (RemoteException e) { e.printStackTrace(); } break; default: super.handleMessage(msg); } } } private final Messenger messengerHandler = new Messenger(new MessengerHandler()); @Nullable @Override public IBinder onBind(Intent intent) { return messengerHandler.getBinder(); } }

Activity中的代码

package com.treeanimals.max.tecent; import android.app.Activity; import android.app.Notification; import android.app.Service; import android.content.ComponentName; import android.content.Context; import android.content.Intent; import android.content.ServiceConnection; import android.os.Bundle; import android.os.Handler; import android.os.IBinder; import android.os.Message; import android.os.Messenger; import android.os.RemoteException; import android.support.annotation.Nullable; import android.util.Log; /** * Created by 95112 on 8/30/2017. */ public class MessagerActivity extends Activity { private static final String TAG = "MessagerActivity"; private Messenger messenger;//用于获取Service的Messenger private Messenger getReplyMessenger =new Messenger(new MessengerHandler() );//接收处理来自Service发来信息的Handler private ServiceConnection connection = new ServiceConnection() {//建立与Service相连接的Connection @Override public void onServiceConnected(ComponentName name, IBinder service) { messenger = new Messenger(service); Message msg = Message.obtain(null,1); Bundle data = new Bundle(); data.putString("msg","test"); msg.setData(data); //绑定回传 msg.replyTo = getReplyMessenger; try{ messenger.send(msg); } catch (RemoteException e) { e.printStackTrace(); } } @Override public void onServiceDisconnected(ComponentName name) { } }; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.messagerlayout); Intent intent = new Intent(this,MessengerService.class); bindService(intent,connection, Context.BIND_AUTO_CREATE); } @Override protected void onDestroy() { unbindService(connection);//解绑 super.onDestroy(); } private static class MessengerHandler extends Handler { @Override public void handleMessage(Message msg) { switch (msg.what) { case 2: Log.d(TAG,msg.getData().getString("reply")); break; default: super.handleMessage(msg); } } } }