Android7.0Messager通信分析

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);            }        }    }}