在Android中控制音乐播放器的音乐

Question

I want to program a music controller in my app, so I would be able to play/pause, skip to the next song or to the previous song in my playlist from another built-in music app. I've seen a solution using broadcast to send messages to all music players to, for example, start playing music. The problem is, music starts playing on three different music players I have installed. Does anybody know what to use instead of sendBroadcast , so that message will be sent only to the app I want?

I found the following solution on the internet. It uses the sendBroadcast method. The message is broadcasted to every music player which I do not want. I want it to be sent only to one specific app.

long eventTime = SystemClock.uptimeMillis();

/*NEXT*/
Intent downIntent = new Intent(Intent.ACTION_MEDIA_BUTTON, null);
KeyEvent downEvent = new KeyEvent(eventTime, eventTime, 
KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_MEDIA_PREVIOUS, 0);
downIntent.putExtra(Intent.EXTRA_KEY_EVENT, downEvent);
sendBroadcast(downIntent, null);

Intent upIntent = new Intent(Intent.ACTION_MEDIA_BUTTON, null);
KeyEvent upEvent = new KeyEvent(eventTime, eventTime, 
KeyEvent.ACTION_UP, KeyEvent.KEYCODE_MEDIA_PREVIOUS, 0);
upIntent.putExtra(Intent.EXTRA_KEY_EVENT, upEvent);
sendBroadcast(upIntent, null);

Answer 1

You cannot send it to just one music player. A broadcast is a system event that triggers an action that other apps can subscribe to. Im pretty sure its very possible to write a music player that does not subscribe to those broadcasts unless Android forces that on you when playing back music (Im not sure wether or not it does, but I think not). So, you are not even sending it to everybody, you send it to the system and whoever subscribed to it will then be able to act on it.

What exactly is the usecase of this app?

Another way you can interact with other apps is an implicit Intent. With that you can call views from other apps and get a result back. This only works with apps/views where the developer of that app allowed this. And does not do what you want either.