android进程间通信ipc Messenger (一)

曾经终败给现在 2022-06-06 01:57 221阅读 0赞

> Messenger跨进程通信底部的实现采用了Binder

**看Messenger的构造函数**

**public final class Messenger implements Parcelable** public Messenger(Handler target) { 
          mTarget = target.getIMessenger();
      }
    
    public Messenger(IBinder target) {
         mTarget = IMessenger.Stub.asInterface(target);
     }

\*\*

> 结合例子来帮助理解

\*\*

*  先创建个服务进程 MService.class

package com.yw.messengerdemo.service;
    
    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.util.Log;
    
    /** * Created by yw on 17/10/26. * author jackyang * com.yw.messengerdemo.service */
    public class MService extends Service { 
        private final static class MHandler extends Handler { 
            @Override
            public void handleMessage(Message msg) {
                switch (msg.what) {
                    case 0:
                        String temp = msg.getData().getString("test");
                        Log.d("yw", temp);
    
                        //给客户端回复消息
                        Messenger m = msg.replyTo;
                        //创建一个消息Message
                        Message message = Message.obtain(null, 1);
                        Bundle  bundle = new Bundle();
                        bundle.putString("msgByService", "客户端小弟，你少给老子发消息啦,我知道你发的消息是：" + temp);
                        message.setData(bundle);
    
                        try {
                            //发送消息
                            m.send(message);
                        } catch (RemoteException e) {
                            e.printStackTrace();
                        }
                        break;
                }
                super.handleMessage(msg);
            }
        }
    
        //实例一个 Messenger
        private final static Messenger mMessenger = new Messenger(new MHandler());
    
        @Override
        public IBinder onBind(Intent intent) {
            //提供给客户端Binder
            return mMessenger.getBinder();
        }
    }

> 配置文件里注册下服务 android:process=”:MService” 创建一个进程

<?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.yw.messengerdemo" >
    
        <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:supportsRtl="true" android:theme="@style/AppTheme" >
            <activity android:name=".MainActivity" android:label="@string/app_name" android:theme="@style/AppTheme.NoActionBar" >
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
    
                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>
            <service android:name=".service.MService" android:process=":MService" />
        </application>
    
    </manifest>

*  MainActivity.class 模拟客户端给服务器发消息

package com.yw.messengerdemo;
    
    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.v7.app.AppCompatActivity;
    import android.view.View;
    import android.widget.EditText;
    import android.widget.TextView;
    
    import com.yw.messengerdemo.service.MService;
    
    public class MainActivity extends AppCompatActivity { 
        private EditText mEt;
        private Messenger mMessenger;
        private TextView mTv;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            mEt = (EditText) findViewById(R.id.et);
            mTv = (TextView) findViewById(R.id.tv);
    
            Intent intent = new Intent(this, MService.class);
            bindService(intent, mServiceConn, Context.BIND_AUTO_CREATE);
        }
    
        public void send_msg(View view) {
            Message message = Message.obtain();
            message.what = 0;
            message.replyTo = new Messenger(mHandler);  //给服务器传一个Messager 为了让服务器用这个Messenger回消息
            Bundle b = new Bundle();
            String msg = mEt.getText().toString();
            b.putString("test", msg);
            message.setData(b);
            try {
                mMessenger.send(message);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
    
        //接受服务器的消息
        private Handler mHandler = new Handler(new Handler.Callback() {
            @Override
            public boolean handleMessage(Message msg) {
                switch (msg.what) {
                    case 1:
                        mTv.setText(msg.getData().getString("msgByService"));
                        break;
                }
                return false;
            }
        });
    
        //创建一个服务连接
        private ServiceConnection mServiceConn = new ServiceConnection() {
            @Override
            public void onServiceConnected(ComponentName name, IBinder service) {
                mMessenger = new Messenger(service);
            }
    
            @Override
            public void onServiceDisconnected(ComponentName name) {
    
            }
        };
    
        @Override
        protected void onDestroy() {
            super.onDestroy();
            unbindService(mServiceConn);
        }
    }

![这里写图片描述][SouthEast]

> 29443-29443/com.yw.messengerdemo:MService D/yw: jackyang  
> 服务端进程打印的log

**注意事项**

1.  服务器进程MService要回消息的话，客户端进程要给传一个Messager

源码下载地址

[SouthEast]: /images/20220606/832f85d3e63e4f6e8480efd60d4bfb02.png