Android - 使用messager实现进程间通信（服务器端→客户端，客户端→服务器端双向）

之前看了一篇，然后不自己动手肯定是不行的，然后自己又写了一遍。

背景：

一般使用messenger进行进程间通信的时候，我们只能进行单方向通信。但是有没有办法让服务器端和客户端进行双向通信呢？

解决思路：

在第一次消息交互的时候，将客户端的消息队列作为一个对象传给服务端，让服务端取到客户端的消息队列。这样就可以实现双向通信了。

代码如下：

需要注意的是，远程绑定service的地方，需要加上包名，不要忘记。

重点关注红色部分，其余的地方没有什么好说的啦。

服务端代码

 package com.example.xxx.server_testmsger;

 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;

 public class MainActivity extends AppCompatActivity {

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
     }
 }

 package com.example.xxx.server_testmsger;

 import android.app.Service;
 import android.content.Intent;
 import android.media.MediaRecorder;
 import android.os.Handler;
 import android.os.IBinder;
 import android.os.Message;
 import android.os.Messenger;
 import android.os.RemoteException;
 import android.util.Log;

 public class serverService extends Service {
     private static final int MSG_WHAT = 1;
     private static final int REQUEST_KEYEVENT = 1;
     private static final int MSG_TOCLIENT = 2;
     private static final int REQUEST_KEYEVENT_TOCLIENT = 2;
     private Messenger mMessenger_from_client = null;

     public serverService() {
     }

     private Messenger mMessager = new Messenger(new Handler() {
         @Override
         public void handleMessage(Message msg) {
             Log.d("Server MSG", "handleMessage()");
             super.handleMessage(msg);

             mMessenger_from_client = (Messenger)msg.obj;
             Message message = msg.obtain(msg);
             Log.d("Server MSG", message.toString());
             switch (message.what) {
                 case MSG_WHAT:
                     Message msgToClient = new Message();
                     msgToClient.what=MSG_TOCLIENT;
                     msgToClient.arg1=REQUEST_KEYEVENT_TOCLIENT;
                     try {
                         Log.d("Server MSG", "sending message....");
                         mMessenger_from_client.send(msgToClient);
                     } catch (RemoteException e) {
                         e.printStackTrace();
                     }
                     break;
                 default:
                     break;
             }
         }

     });

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

客户端代码

 package com.example.xxx.client_testmsger;

 import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
 import android.content.ServiceConnection;
 import android.os.Handler;
 import android.os.IBinder;
 import android.os.Message;
 import android.os.Messenger;
 import android.os.RemoteException;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.ContextThemeWrapper;
 import android.view.View;
 import android.widget.Button;

 import java.io.InputStream;

 public class MainActivity extends AppCompatActivity {
     private Messenger mMessenger = null;
     private Messenger mServiceMessenger = null;
     private Intent serviceIntent;
     private static final int MSG_WHAT = 1;
     private static final int REQUEST_KEYEVENT = 1;
     private static final int MSG_TOCLIENT = 2;
     private static final int REQUEST_KEYEVENT_TOCLIENT = 2;

     private Handler mHandler = new Handler() {
         @Override
         public void handleMessage(Message msg) {
             super.handleMessage(msg);
             switch (msg.what) {
                 case MSG_TOCLIENT:
                     Log.e("Client MSG","got Message from server");
                     Log.e("Client MSG",msg.toString());
                     break;
                 default:
                     break;
             }
         }
     };
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);

         serviceIntent = new Intent();
         serviceIntent.setComponent(new ComponentName("com.example.xxx.server_testmsger","com.example.xxx.server_testmsger.serverService"));
         bindService(serviceIntent, mConnection, Context.BIND_AUTO_CREATE);
         mMessenger = new Messenger(mHandler);
     }

     private ServiceConnection mConnection = new ServiceConnection() {
         @Override
         public void onServiceConnected(ComponentName name, IBinder service) {
             Log.e("MSG","MainActivity Start");
             Log.d("Client MSG", "onServiceConnected()");
             if (service == null) {
                 mServiceMessenger = null;
             } else {
                 mServiceMessenger = new Messenger(service);
                 Message message = new Message();
                 message.what = MSG_WHAT;
                 message.arg1 = REQUEST_KEYEVENT;
                 message.obj = mMessenger;
                 try {
                     Log.d("Client MSG", "Message send()");
                     mServiceMessenger.send(message);
                 } catch (RemoteException e) {
                     e.printStackTrace();
                 }
             }
         }

         @Override
         public void onServiceDisconnected(ComponentName name) {
             Log.d("Client MSG", "onServiceDisconnected()");
             mServiceMessenger = null;
         }
     };

     @Override
     public void onDestroy() {
         super.onDestroy();
         unbindService(mConnection);
     }
 }