For studying the Android service, I wrote a test program that have three button "bind service", "unbind service" and "send echo" on the screen. When clicked, they use bindService(), unbindService() and a Messenger to communicate with the service.
Here is the service codes:
public class MessengerService extends Service {
private final Messenger mMessenger = new Messenger(new TempHandler());
private class TempHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_SAY_HELLO:
Toast.makeText(getApplicationContext(), "Hi, there.", Toast.LENGTH_SHORT).show();
break;
case MSG_SAY_GOODBYE:
Toast.makeText(getApplicationContext(), "See you next time.", Toast.LENGTH_SHORT).show();
break;
case MSG_ECHO:
Toast.makeText(getApplicationContext(), "Received " + msg.arg1 + " from client.", Toast.LENGTH_SHORT).show();
Messenger replyMessenger = msg.replyTo;
Message replyMsg = Message.obtain(null, MSG_ECHO, msg.arg1, 0);
try {
replyMessenger.send(replyMsg);
} catch (RemoteException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
default:
super.handleMessage(msg);
}
}
}
@Override
public IBinder onBind(Intent intent) {
Toast.makeText(getApplicationContext(), "Service bound", Toast.LENGTH_SHORT).show();
return mMessenger.getBinder();
}
@Override
public void onDestroy() {
Log.d("", "Service.onDestroy()...");
super.onDestroy();
}
}
And here is the activity code:
public class MessengerActivity extends Activity {
private Messenger mMessengerService;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity2);
Button bind = (Button) findViewById(R.id.button5);
bind.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
doBindService();
}
});
Button unbind = (Button) findViewById(R.id.button6);
unbind.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
doUnbindService();
}
});
Button echo = (Button) findViewById(R.id.button7);
echo.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
doSendEcho();
}
});
}
private void doBindService() {
Intent intent = new Intent(getApplicationContext(), MessengerService.class);
bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
}
private void doUnbindService() {
Message msg = Message.obtain(null, MessengerService.MSG_SAY_GOODBYE);
try {
mMessengerService.send(msg);
} catch (RemoteException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
unbindService(mConnection);
}
private void doSendEcho() {
if (mMessengerService != null) {
Message msg = Message.obtain(null, MessengerService.MSG_ECHO, 12345, 0);
msg.replyTo = mMessenger;
try {
mMessengerService.send(msg);
} catch (RemoteException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
private final Messenger mMessenger = new Messenger(new TempHandler());
private ServiceConnection mConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Toast.makeText(getApplicationContext(), "Service is connected.", Toast.LENGTH_SHORT).show();
mMessengerService = new Messenger(service);
Message msg = Message.obtain(null, MessengerService.MSG_SAY_HELLO);
try {
mMessengerService.send(msg);
} catch (RemoteException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void onServiceDisconnected(ComponentName name) {
mMessengerService = null;
Toast.makeText(getApplicationContext(), "Service is disconnected.", Toast.LENGTH_SHORT).show();
}
};
private class TempHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MessengerService.MSG_ECHO:
Toast.makeText(getApplicationContext(), "Get the echo message (" + msg.arg1 + ")", Toast.LENGTH_SHORT).show();
break;
default:
super.handleMessage(msg);
}
}
}
}
When I click "bind service" and "send echo" button. I can see the service is connected and the message communication is good. And then click "unbind service", I saw the service onDestroy() be called, so I expect the service is stopped and should not respond to the coming message again. But actually is, the service seems still alive and I could get the echo message again when click the "send echo" button. So I'm wondering is there anything I made incorrect? Or maybe I'm not fully understand about the service?
Hope someone can help, thanks.
