Messenger 实现Activity与Service通讯、进程通讯

2011-05-07 15:49

Messenger 实现Activity与Service通讯、进程通讯

信使 主要用于进程通讯详见SDK 

                            android.os.Messenger 

一、Activity通过Messenger发送信息给Service

      1、创建项目Messenger 包名：com.Messenger.main

       2、创建消息结构体MSG.java

             package com.Messenger.main;

                   public class MSG {

static final int MSG_ONE = 1;

static final int MSG_TWO = 2;

static final int MSG_THREE = 3;

static final int MSG_FOUR = 4;

                   }

       3、创建MessengerActivity.java

             通过ServiceConnection服务通讯控制类接口来获得Service的连接并创建Messenger对象

重点：绑定服务器

           bindService(new Intent(this,MessengerService.class), 

           this.mConnection, Context.BIND_AUTO_CREATE);

代码：

import android.app.Activity;

import android.content.ComponentName;

import android.content.Context;

import android.content.Intent;

import android.content.ServiceConnection;

import android.os.Bundle;

import android.os.IBinder;

import android.os.Message;

import android.os.Messenger;

import android.os.RemoteException;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

 

public class MessengerActivity extends Activity {

 

private Messenger mServiceSend;

private boolean mBound;

private Button mButton;

/**

*服务通讯类接口

    */

private ServiceConnection mConnection = new ServiceConnection() {

@Override

public void onServiceDisconnected(ComponentName name) {

// TODO Auto-generated method stub

mServiceSend = null;

mBound = false;

}

@Override

public void onServiceConnected(ComponentName name, IBinder service) {

// TODO Auto-generated method stub

/*

*Activity通过Service成功连接后返回的IBinder对象构建

*之后通过该IBunder与Service实现通讯

*/

mServiceSend  = new Messenger(service);

mBound = true;

}

};

public void doService(){

/*

*创建并发送消息给Service

*/

try {

Message msg = Message.obtain(null, MSG.MSG_ONE,0,0);

mServiceSend.send(msg);

} catch (RemoteException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

/** Called when the activity is first created. */

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        mButton = (Button)findViewById(R.id.button1);

        

        mButton.setOnClickListener(new OnClickListener(){

 

@Override

public void onClick(View arg0) {

// TODO Auto-generated method stub

doService();

}

        

        });

    }

 

@Override

protected void onDestroy() {

// TODO Auto-generated method stub

super.onDestroy();

//取消绑定

if(mBound){

unbindService(mConnection);

mBound = false;

}

}

 

@Override

protected void onStart() {

// TODO Auto-generated method stub

super.onStart();

//绑定到服务器

bindService(new Intent(this,MessengerService.class), 

this.mConnection, Context.BIND_AUTO_CREATE);

}

}

      4、让Messenger继承Service

package com.Messenger.main;

 

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 final String log = "MessengerService";

DataStruct mDataInfo = new DataStruct();

/*

创建发送/接收消息的IncomingHandler

*/

final Messenger mMessenger = new Messenger(new IncomingHandler());

/**

* 来自客户端消息的handler

*/

class IncomingHandler extends Handler{

 

@Override

public void handleMessage(Message msg) {

// TODO Auto-generated method stub

super.handleMessage(msg);

switch (msg.what) {

case MSG.MSG_ONE:

Toast.makeText(getApplicationContext(), "Hello Activity.", Toast.LENGTH_LONG).show();

break;

case MSG.MSG_TWO:

break;

case MSG.MSG_THREE:

break;

case MSG.MSG_FOUR:

break;

default:

break;

}

}

}

/*

当绑定服务时，返回一个接口给messenger，为了发送消息给服务器

*/

@Override

public IBinder onBind(Intent intent) {

// TODO Auto-generated method stub

Log.i(log, "binding.");

return mMessenger.getBinder();

}

@Override

public void onStart(Intent intent, int startId) {

// TODO Auto-generated method stub

Log.i(log, "Service Start.");

super.onStart(intent, startId);

}

主要实现：(main.xml见Messenger 实现Activity与Service通讯、进程通讯（二）)Service通过返回Messenger的Binder给绑定它的Activity实现通讯。

Service通过Handler监听返回信息，Activity通过ServiceConnection来获得Service的Binder并创建Activity的Messenger对象

下部分通过Messenger实现进程间通讯，Activity发送信息给另一进程的Service。