Service 如何給 Activity 發(fā)送 Message 見《Activity 調(diào)用 Service 中的方法都有哪些方式?》題目中 Activity 跟 Service 綁定的第二種方式:Using a Messenger其弊。
考慮到官方只給出了 Activity 給 Service 發(fā)送 Message 的代碼巫橄，在這里我給出一個 Activity 跟 Service 之間互相 發(fā)送 Message 通信的示例代碼:
- MainActivity 代碼
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 互發(fā) Message *
* @author wzy 2015-11-25
*
*/
public class MainActivity extends Activity {
private Messenger messenger;
//將該 Handler 發(fā)送 Service
private Messenger mOutMessenger = new Messenger(new OutgoingHandler());
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
// 綁定服務(wù)
public void click1(View view) {
Intent intent = new Intent(this, MessengerService.class);
ServiceConnection conn = new MyServiceConnection();
bindService(intent, conn, Service.BIND_AUTO_CREATE);
}
// 發(fā)送消息
public void click2(View view) throws RemoteException {
if (messenger == null) {
Toast.makeText(this, "服務(wù)不可用!", Toast.LENGTH_SHORT).show();
return; }
Message message = new Message();
message.obj="長江長江我是黃河"; 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, "連接成功!", Toast.LENGTH_SHORT).show(); messenger = new Messenger(service);
Message message=new Message();
message.what = 1;
//Activity 綁定 Service 的時候給 Service 發(fā)送一個消息，該消息的 obj 屬性是一個 Messenger 對象 message.obj = mOutMessenger;
try {
messenger.send(message);
} catch (RemoteException e) {
e.printStackTrace();
}
}
@Override
public void onServiceDisconnected(ComponentName name) {
Toast.makeText(MainActivity.this, "連接已經(jīng)斷開!", Toast.LENGTH_SHORT).show(); }
}
}
- MessengerService 代碼
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;
/**
* 該 Service 接收到 Activity 的消息后會在返回一條消息
* @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.定義一個 Handler 對象窑眯，該 Handler 處理 Activity 發(fā)送過來的消息 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", "已經(jīng)獲取到 Activity 發(fā)送了的 Messenger 對象");
break;
default:
break;
}
} }
