Service 如何给 Activity 发送 Message 见《Activity 调用 Service 中的方法都有哪些方式?》题目中 Activity 跟 Service 绑定的第二种方式:Using a Messenger。
考虑到官方只给出了 Activity 给 Service 发送 Message 的代码，在这里我给出一个 Activity 跟 Service 之间互相 发送 Message 通信的示例代码:
- MainActivity 代码
package com.example.serviceAndActivity;
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.app.Activity;
import android.app.Service;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.util.Log;
import android.view.View;
import android.widget.Toast;
/**
* Activity 和 Service 互发 Message *
* @author wzy 2015-11-25
*
*/
public class MainActivity extends Activity {
private Messenger messenger;
//将该 Handler 发送 Service
private Messenger mOutMessenger = new Messenger(new OutgoingHandler());
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
// 绑定服务
public void click1(View view) {
Intent intent = new Intent(this, MessengerService.class);
ServiceConnection conn = new MyServiceConnection();
bindService(intent, conn, Service.BIND_AUTO_CREATE);
}
// 发送消息
public void click2(View view) throws RemoteException {
if (messenger == null) {
Toast.makeText(this, "服务不可用!", Toast.LENGTH_SHORT).show();
return; }
Message message = new Message();
message.obj="长江长江我是黄河"; message.what =0; messenger.send(message);
}
class OutgoingHandler extends Handler{
@Override
public void handleMessage(Message msg) {
Log.d("tag", msg.toString());
} }
class MyServiceConnection implements ServiceConnection {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Toast.makeText(MainActivity.this, "连接成功!", Toast.LENGTH_SHORT).show(); messenger = new Messenger(service);
Message message=new Message();
message.what = 1;
//Activity 绑定 Service 的时候给 Service 发送一个消息，该消息的 obj 属性是一个 Messenger 对象 message.obj = mOutMessenger;
try {
messenger.send(message);
} catch (RemoteException e) {
e.printStackTrace();
}
}
@Override
public void onServiceDisconnected(ComponentName name) {
Toast.makeText(MainActivity.this, "连接已经断开!", Toast.LENGTH_SHORT).show(); }
}
}
- MessengerService 代码
package com.example.serviceAndActivity;
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;
/**
* 该 Service 接收到 Activity 的消息后会在返回一条消息
* @author wzy 2015-11-25
*
*/
public class MessengerService extends Service {
private Messenger messenger = new Messenger(new IncomingHandler()); private Messenger mActivityMessenger ;
@Override
public IBinder onBind(Intent intent) {
IBinder binder = messenger.getBinder();
return binder;
}
//1.定义一个 Handler 对象，该 Handler 处理 Activity 发送过来的消息 class IncomingHandler extends Handler{
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case 0:
Log.d("tag", msg.toString());
if (mActivityMessenger!=null) {
Message message= new Message();
message.what = 2;
message.obj="地瓜地瓜我是土豆";
try {
mActivityMessenger.send(message);
} catch (RemoteException e) {
e.printStackTrace();
}
}
break;
case 1:
mActivityMessenger = (Messenger) msg.obj;
Log.d("tag", "已经获取到 Activity 发送了的 Messenger 对象");
break;
default:
break;
}
} }
