/*

* Copyright 2009 Weaver authors

*

* This code is part of the Weaver tutorial and may be freely used.

*/

import java.util.HashMap;

import java.util.Map;

/**

* Provides a layer between a {@link Controller} that plays audio, and the

* underlying {@link AudioService}. Maintains a mapping between the

* audio tokens used by the AudioService and the corresponding controller

* object.

* <p>

* This is a simplified version of a real class, and is used to

* illustrate potential race conditions.

*

* @author alasdair.mackintosh@gmail.com (Alasdair Mackintosh)

*/

public class Player implements AudioListener {

/** Maps an audio token onto the corresponding Controller */

private Map<Integer, Controller> controllerMap = new HashMap<Integer,Controller>();

private AudioService service;

public Player(AudioService service) {

this.service = service;

}

/**

* Plays the given media asset. When the asset has finished playing,

* invokes {@link Controller#onFinished}.

*/

public int playAsset(String assetName, Controller controller) {

validateAsset(assetName);

// Start playing the asset, and get the token that identifies the audio stream.

int token = service.cue(assetName, this);

// Add a mapping from token back to the controller that owns it.

controllerMap.put(token, controller);

return token;

}

/**

* Invoked by the audio service when the asset has finished

* playing. Calls the controller's {@link Controller#onFinished} method.

*/

@Override

public void onAudioPlayed(int audioToken) {

Controller controller = controllerMap.get(audioToken);

if (controller == null) {

throw new IllegalStateException("No controller for token " + audioToken);

}

controller.onFinished(audioToken);

}

private void validateAsset(String assetName) {

if (assetName == null) {

throw new NullPointerException();

}

}

}