写在前面的话
前面我写了一篇文章—android学习之remote service 的aidl详解，讲到跨进程多线程通信，我们使用aidl技术来实现。但是平时我们可能只要要求跨进程通信，而不需要使用多线程，那么这时候，Messenger就是我们的一个非常好的选择。
Messenger实例
Server端：
MessengerService.java
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;
import android.widget.Toast;
public class MessengerService extends Service {
public static final String TAG = "MessengerService";
public static final int MSG_SEND_TO_SERVER = 1;
public static final int MSG__REPLY_FROM_SERVER = 2;
final Messenger mMessenger = new Messenger(new IncomingHandler());
class IncomingHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_SEND_TO_SERVER:
Log.i(TAG, "MSG_SEND_TO_SERVER:"+"--msg.arg1:"+msg.arg1+"--msg.arg2:"+msg.arg2);
try {
Message messageReplyToClient = new Message();
messageReplyToClient.what = MSG__REPLY_FROM_SERVER;
messageReplyToClient.arg1 = msg.arg2;
messageReplyToClient.arg2 = msg.arg1;
msg.replyTo.send(messageReplyToClient);
} catch (RemoteException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
break;
default:
super.handleMessage(msg);
}
}
}
@Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
Toast.makeText(getApplicationContext(), "binding", Toast.LENGTH_SHORT).show();
return mMessenger.getBinder();
}
}Client端
MainActivity.java
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.widget.Button;
import android.widget.TextView;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
public class MainActivity extends Activity {
public static final String TAG = "MainActivity";
public static final int MSG_SEND_TO_SERVER = 1;
public static final int MSG__REPLY_FROM_SERVER = 2;
private Messenger mMessenger;
boolean mBound;
private TextView textViewShowConnectState;
private TextView textViewMessageSendToService;
private TextView textViewMessageReceiverFromService;
private Button button;
private Messenger mMessengerReceive = new Messenger(new MyHandler());
class MyHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG__REPLY_FROM_SERVER:
Log.i(TAG, "MSG__REPLY_FROM_SERVER:"+"--msg.arg1="+msg.arg1+"--msg.arg2="+msg.arg2);
textViewMessageReceiverFromService.setText("msg:server-->client:"+"--msg.arg1="+msg.arg1+"--msg.arg2="+msg.arg2);
break;
default:
super.handleMessage(msg);
}
}
}
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder service) {
mMessenger = new Messenger(service);
mBound = true;
textViewShowConnectState.setText("service connect");
}
public void onServiceDisconnected(ComponentName className) {
mMessenger = null;
mBound = false;
textViewShowConnectState.setText("service disconnect");
}
};
public void sendMessage(View v) {
if (!mBound) return;
// Create and send a message to the service, using a supported ‘what‘ value
int arg1 = (int) (Math.random() * 100);;
int arg2 = (int) (Math.random() * 100);;
Message msg = Message.obtain(null, MSG_SEND_TO_SERVER, arg1, arg2);
msg.replyTo = mMessengerReceive;
textViewMessageSendToService.setText("msg:client-->server:"+"--msg.arg1="+msg.arg1+"--msg.arg2="+msg.arg2);
try {
mMessenger.send(msg);
} catch (RemoteException e) {
e.printStackTrace();
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
}
private void init() {
// TODO Auto-generated method stub
textViewShowConnectState = (TextView)findViewById(R.id.textViewShowConnectState);
textViewMessageSendToService = (TextView)findViewById(R.id.textViewMessageSendToService);
textViewMessageReceiverFromService = (TextView)findViewById(R.id.textViewMessageReceiverFromService);
button = (Button)findViewById(R.id.button);
}
@Override
protected void onStart() {
super.onStart();
bindService(new Intent("com.android.ACTION.MessengerService"), mConnection,
Context.BIND_AUTO_CREATE);
}
@Override
protected void onStop() {
super.onStop();
if (mBound) {
unbindService(mConnection);
mBound = false;
}
}
}我们Client给Server发送消息的是封装在sendMessage方法中的：
mMessenger.send(msg);那么如何响应从server端回传的消息了，这中间的关键是把client发送到server的消息msg与回调处理的Messenger mMessengerReceive相关联：
msg.replyTo = mMessengerReceive;布局文件：
activity_main.xml
<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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<TextView
android:id="@+id/textViewShowConnectState"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/textViewShowConnectState"
android:onClick="sendMessage"
android:text="click send message to Server"
/>
<TextView
android:id="@+id/textViewMessageSendToService"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/button"/>
<TextView
android:id="@+id/textViewMessageReceiverFromService"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/textViewMessageSendToService"/>
</RelativeLayout>效果图
从源码和效果图，我们可以看出，这个Demo是从Client发送一个消息到Server，Server把消息的msg.arg1和msg.arg2的值交换后再反馈给Client，Client将从Client发送到Server的消息和Server返回的消息都显示出来。
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时间： 2024-10-15 20:39:18