简介
Messenger是安卓进程间通信 (IPC) 最为简单的方式，可以实现进程间双向通信。详见官网介绍
代码实现
服务端应用实现
MessengerService接收客户端发送的消息：
package com.test.messengerservice;
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 androidx.annotation.NonNull;
public class MessengerService extends Service {
//接收客户端的消息类型
private static final int SEND_MESSENGER = 0;
private static final int CONFIG_NET = 1;
private static final int CANCEL = 2;
//发送给客户端的消息类型
private static final int FIND_DEVICE = 10;
public MessengerService() {
}
private Messenger messenger = new Messenger(new ServiceHandler());
private static Messenger mClient;
public class ServiceHandler extends Handler {
@Override
public void handleMessage(@NonNull Message msg) {
// 处理消息
switch(msg.what){
case SEND_MESSENGER:
Log.d("service", "receive messenger");
mClient = msg.replyTo;
break;
case CONFIG_NET:
Log.d("service", "config net task");
mClient = msg.replyTo;
break;
case CANCEL:
Log.d("service", "cancel task");
mClient = msg.replyTo;
break;
default:
break;
}
}
}
@Override
public IBinder onBind(Intent intent) {
Log.i("service", "service bind");
return messenger.getBinder();
}
@Override
public boolean onUnbind(Intent intent) {
Log.i("service", "service unbind");
mClient = null;
return super.onUnbind(intent);
}
//向客户端发送消息
public static void sendMessage() {
if (null == mClient) {
Log.d("service", "client is null");
return;
}
try {
Message message = Message.obtain(null, FIND_DEVICE);
mClient.send(message);
} catch (RemoteException e) {
e.printStackTrace();
}
}
}
AndroidManifest.xml中注册messenger服务：
<service
android:name=".MessengerService"
android:enabled="true"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MESSENGER"/>
</intent-filter>
</service>
MainActivity中设置按钮用于向客户端主动发送消息：
package com.test.messengerservice;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
private Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = findViewById(R.id.findDeviceButton);
button.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View v) {
MessengerService.sendMessage();
}
});
}
}
客户端应用实现
MainActivity中绑定服务端的service，并设置向客户端发送消息的按钮：
package com.test.messengerclient;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.content.ComponentName;
import android.content.Context;
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.widget.Button;
public class MainActivity extends AppCompatActivity {
// 服务端的Messenger
private Messenger mService;
// 客户端的Messenger
private Messenger mMessenger;
private Button buttonConfigNet;
private Button buttonCancel;
//发送给服务端的消息类型
private static final int SEND_MESSENGER = 0;
private static final int CONFIG_NET = 1;
private static final int CANCEL = 2;
//接收服务端的消息类型
private static final int FIND_DEVICE = 10;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//客户端Messenger
mMessenger = new Messenger(new ClientHandler());
//绑定服务
bindServiceInvoked();
//设置点击事件
buttonConfigNet = findViewById(R.id.buttonConfigNet);
buttonCancel = findViewById(R.id.buttonCancel);
buttonConfigNet.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(mService != null) {
try {
Log.d("client", "send config net");
Message message = Message.obtain(null, CONFIG_NET);
message.replyTo = mMessenger;
mService.send(message);
} catch (RemoteException e) {
e.printStackTrace();
}
}
}
});
buttonCancel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(mService != null) {
try {
Log.d("client", "send cancel");
Message message = Message.obtain(null, CANCEL);
message.replyTo = mMessenger;
mService.send(message);
} catch (RemoteException e) {
e.printStackTrace();
}
}
}
});
}
//接收服务连接和断开消息
ServiceConnection serviceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Log.i("client", "service connected");
mService = new Messenger(service);
//由于绑定后服务端没有客户端的Messenger ，绑定后先将客户端Messenger发送给服务端
if(mService != null) {
try {
Log.d("client", "send messenger");
Message message = Message.obtain(null, SEND_MESSENGER);
message.replyTo = mMessenger;
mService.send(message);
} catch (RemoteException e) {
e.printStackTrace();
}
}
}
@Override
public void onServiceDisconnected(ComponentName name) {
Log.i("client", "service disconnected");
mService = null;
}
};
//从服务端接收消息
public class ClientHandler extends Handler {
@Override
public void handleMessage(@NonNull Message msg) {
switch (msg.what){
case FIND_DEVICE:
Log.i("client", "find device");
break;
}
}
}
//绑定服务端的service
private void bindServiceInvoked()
{
Intent intent = new Intent();
intent.setAction("android.intent.action.MESSENGER");
intent.setPackage("com.test.messengerservice");
bindService(intent, serviceConnection, Context.BIND_AUTO_CREATE);
}
}
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