PlayerApplet.java

/*
 * 11/19/04		1.0 moved to LGPL.
 * 29/01/00		Initial version. mdm@techie.com
 *-----------------------------------------------------------------------
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library General Public License as published
 *   by the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU Library General Public License for more details.
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this program; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *----------------------------------------------------------------------
 */

package audio.javazoom.jl.player;

import java.applet.Applet;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;

import audio.javazoom.jl.decoder.JavaLayerException;


/**
 * A simple applet that plays an MPEG audio file. 
 * The URL (relative to the document base)
 * is passed as the "audioURL" parameter. 
 * 
 * @author	Mat McGowan
 * @since	0.0.8
 */
public class PlayerApplet extends Applet implements Runnable
{
	static public final String AUDIO_PARAMETER = "audioURL";
	
	/**
	 * The Player used to play the MPEG audio file. 
	 */
	private Player	player = null;
	
	/**
	 * The thread that runs the player.
	 */
	private Thread	playerThread = null;	
	
	private String	fileName = null;
	
	
	/**
	 * Retrieves the <code>AudioDevice</code> instance that will
	 * be used to sound the audio data. 
	 * 
	 * @return	an audio device instance that will be used to 
	 *			sound the audio stream.
	 */
	protected AudioDevice getAudioDevice() throws JavaLayerException
	{
		return FactoryRegistry.systemRegistry().createAudioDevice();
	}
	
	/**
	 * Retrieves the InputStream that provides the MPEG audio
	 * stream data. 
	 * 
	 * @return	an InputStream from which the MPEG audio data
	 *			is read, or null if an error occurs. 
	 */
	protected InputStream getAudioStream()
	{
		InputStream in = null;
		
		try
		{
			URL url = getAudioURL();
			if (url!=null)			
				in = url.openStream();
		}
		catch (IOException ex)
		{
			System.err.println(ex);
		}
		return in;
	}

	protected String getAudioFileName()
	{
		String urlString = fileName;
		if (urlString==null)
		{
			urlString = getParameter(AUDIO_PARAMETER);
		}
		return urlString;
	}
	
	protected URL getAudioURL()
	{				
		String urlString = getAudioFileName();
		URL url = null;
		if (urlString!=null)
		{
			try
			{
				url = new URL(getDocumentBase(), urlString);				
			}
			catch (Exception ex)
			{
				System.err.println(ex);	
			}
		}		
		return url;
	}
	
	/**
	 * Sets the URL of the audio stream to play.
	 */
	public void setFileName(String name)
	{
		fileName = name;
	}
	
	public String getFileName()
	{
		return fileName;	
	}
	
	/**
	 * Stops the audio player. If the player is already stopped
	 * this method is a no-op.  
	 */
	protected void stopPlayer() throws JavaLayerException
	{
		if (player!=null)
		{
			player.close();
			player = null;
			playerThread = null;
		}
	}
	
	/**
	 * Decompresses audio data from an InputStream and plays it
	 * back through an AudioDevice. The playback is run on a newly
	 * created thread. 
	 * 
	 * @param in	The InputStream that provides the MPEG audio data.
	 * @param dev	The AudioDevice to use to sound the decompressed data. 
	 * 
	 * @throws JavaLayerException if there was a problem decoding
	 *		or playing the audio data.
	 */
	protected void play(InputStream in, AudioDevice dev) throws JavaLayerException
	{
		stopPlayer();
		
		if (in!=null && dev!=null)
		{
			player = new Player(in, dev, 100);
			playerThread = createPlayerThread();
			playerThread.start();
		}
	}
	
	/**
	 * Creates a new thread used to run the audio player.
	 * @return A new Thread that, once started, runs the audio player.
	 */
	protected Thread createPlayerThread()
	{
		return new Thread(this, "Audio player thread");	
	}
	
	/**
	 * Initializes this applet.
	 */
	public void init()
	{		
	}
	
	/**
	 * Starts this applet. An input stream and audio device 
	 * are created and passed to the play() method.
	 */
	public void start()
	{
		String name = getAudioFileName();
		try
		{			
			InputStream in = getAudioStream();
			AudioDevice dev = getAudioDevice();
			play(in, dev);
		}
		catch (JavaLayerException ex)
		{
			synchronized (System.err)
			{
				System.err.println("Unable to play "+name);
				ex.printStackTrace(System.err);
			}
		}
	}	
	
	/**
	 * Stops this applet. If audio is currently playing, it is
	 * stopped.
	 */
	public void stop()
	{
		try
		{
			stopPlayer();
		}
		catch (JavaLayerException ex)
		{
			System.err.println(ex);
		}
	}
	
	public void destroy()
	{
	}
	
	/**
	 * The run method for the audio player thread. Simply calls
	 * play() on the player to play the entire stream. 
	 */
	public void run()
	{				
		if (player!=null)
		{
			try
			{
				player.play();				
			}
			catch (JavaLayerException ex)
			{
				System.err.println("Problem playing audio: "+ex);
			}			
		}
	}
}