通过messenger实现activity与service的相互通信

布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.zzw.testmessenger.MainActivity" >

    <Button
        android:id="@+id/bind"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:text="绑定" />

    <Button
        android:id="@+id/send"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:text="发送数据" />

    <Button
        android:id="@+id/start"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:text="加法" />

</RelativeLayout>

MainActivity：

package com.zzw.testmessenger;

import android.app.Activity;
import android.content.ComponentName;
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.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity implements OnClickListener {
    Button bind, send, start;
    ServiceConnection sc;
    Messenger sender, receiver;
    int sum;
    Handler handler;

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

        bind = (Button) findViewById(R.id.bind);
        bind.setOnClickListener(this);
        send = (Button) findViewById(R.id.send);
        send.setOnClickListener(this);
        start = (Button) findViewById(R.id.start);
        start.setOnClickListener(this);

        handler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                if (msg.what == 1) {
                    int sum = (Integer) msg.obj;
                    Log.d("收到服务器传来的消息--->", sum + "");
                }
            }
        };
        //activity接收serviece的数据的接收者
        receiver = new Messenger(handler);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
        case R.id.bind:
            bindService();
            break;
        case R.id.send:
            sendMessageToService();
            break;
        case R.id.start:
            StartService();
            break;
        }
    }

    private void bindService() {
        sc = new ServiceConnection() {
            @Override
            public void onServiceDisconnected(ComponentName name) {
            }

            @Override
            public void onServiceConnected(ComponentName name, IBinder service) {
                //activity向serviece的发送数据的发送者
                sender = new Messenger(service);
            }
        };
        Intent intent = new Intent(MainActivity.this, MessengerService.class);
        bindService(intent, sc, BIND_AUTO_CREATE);
    }

    private void StartService() {
        Intent it = new Intent(MainActivity.this, MessengerService.class);
        startService(it);
    }

    private void sendMessageToService() {
        try {
            Message msg = new Message();
            int a = (int) (Math.random() * 20);
            int b = (int) (Math.random() * 20);
            int s[] = { a, b };

            msg.what = 0;
            msg.obj = s;

            // 设置一个Messenger receiver，receiver是提供给Service使用来给Activity响应的目标。
            msg.replyTo = receiver;
            sender.send(msg);

            Log.d("sendMessageToService", "发送成功----->");
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void onDestroy() {
        unbindService(sc);
        Intent intent = new Intent(MainActivity.this, MessengerService.class);
        stopService(intent);
        super.onDestroy();
    }
}

MessengerService：

package com.zzw.testmessenger;

import android.app.Service;
import android.content.Intent;
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 MessengerService extends Service {
    private Messenger messenger, sender;
    Handler handler;
    int a, b, sum;

    @Override
    public void onCreate() {
        Log.d("MessengerSerivice", "onCreate");
        handler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                if (msg.what == 0) {
                    int[] s = (int[]) msg.obj;
                    a = s[0];
                    b = s[1];
                    Log.d("从activity收到的msg", "a=" + a + "  b=" + b);
                }
                //service向activity发送数据的发送者
                sender = msg.replyTo;
            }
        };
        //service接收activity的数据的接收者
        messenger = new Messenger(handler);
    }

    private void sendMessageToActivity(Messenger sender) {
        try {
            Message msg = new Message();
            msg.what = 1;
            msg.obj = sum;
            sender.send(msg);
            Log.d("sendMessageToActivity", "成功发送");
        } catch (RemoteException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.d("MessengerSerivice", "onStartCommand");
        sum = a + b;
        Log.d("在onStartCommand中算出的和", sum + "");
        sendMessageToActivity(sender);
        
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public IBinder onBind(Intent intent) {
        Log.d("MessengerSerivice", "onBind");
        return messenger.getBinder();
    }

}