Android Messenger实现进程间双向通信

 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(); } } }

 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(); } }); } }

 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); } }