simpleaudioplayer.java

这是一个简单的用JMF完成的播放器软件

package com.gjunit.CRT;
import	java.io.File;
import	java.io.IOException;


import	javax.sound.sampled.AudioFormat;
import	javax.sound.sampled.AudioInputStream;
import	javax.sound.sampled.AudioSystem;
import	javax.sound.sampled.DataLine;
import	javax.sound.sampled.LineUnavailableException;
import	javax.sound.sampled.SourceDataLine;  


  /*	+DocBookXML
	<title>Playing an audio file (easy)</title>

	<formalpara><title>Purpose</title>
	<para>Plays a single audio file.</para></formalpara>

	<formalpara><title>Level</title>
	<para>Newbies</para></formalpara>

	<formalpara><title>Usage</title>
	<cmdsynopsis>
	<command>java SimpleAudioPlayer</command>
	<replaceable class="parameter">audiofile</replaceable>
	</cmdsynopsis>
	</formalpara>

	<formalpara><title>Parameters</title>
	<variablelist>
	<varlistentry>
	<term><option><replaceable class="parameter">audiofile</replaceable></option></term>
	<listitem><para>the name of the
	audio file that should be played</para></listitem>
	</varlistentry>
	</variablelist>
	</formalpara>

	<formalpara><title>Bugs, limitations</title>
	<para>Only PCM encoded files are supported. A-law, μ-law,
	ADPCM, mp3 and other compressed data formats are not supported. For
	playing these, see AudioPlayer.</para>
	</formalpara>
		
	<formalpara><title>Source code</title>
	<para>
	<ulink url="SimpleAudioPlayer.java.html">SimpleAudioPlayer.java</ulink>
	</para>
	</formalpara>

-DocBookXML
*/  
public class SimpleAudioPlayer
{
	private static final int	EXTERNAL_BUFFER_SIZE = 128000;

	public static void main(String[] args)
 	{
	
		String	strFilename = "D:\\a.mp3 ";
		File	soundFile = new File(strFilename);
	
		/*
		  We have to read in the sound file.
		*/
		AudioInputStream	audioInputStream = null;
		try
		{
			audioInputStream = AudioSystem.getAudioInputStream(soundFile);
		}
		catch (Exception e)
		{
			/*
			  In case of an exception, we dump the exception
			  including the stack trace to the console output.
			  Then, we exit the program.
			*/
			e.printStackTrace();
		}

		/*
		  From the AudioInputStream, i.e. from the sound file,
		  we fetch information about the format of the
		  audio data.
		  These information include the sampling frequency,
		  the number of
		  channels and the size of the samples.
		  These information
		  are needed to ask Java Sound for a suitable output line
		  for this audio file.
		*/
		AudioFormat	audioFormat = audioInputStream.getFormat();

		/*
		  Asking for a line is a rather tricky thing.
		  We have to construct an Info object that specifies
		  the desired properties for the line.
		  First, we have to say which kind of line we want. The
		  possibilities are: SourceDataLine (for playback), Clip
		  (for repeated playback)	and TargetDataLine (for
		  recording).
		  Here, we want to do normal playback, so we ask for
		  a SourceDataLine.
		  Then, we have to pass an AudioFormat object, so that
		  the Line knows which format the data passed to it
		  will have.
		  Furthermore, we can give Java Sound a hint about how
		  big the internal buffer for the line should be. This
		  isn't used here, signaling that we
		  don't care about the exact size. Java Sound will use
		  some default value for the buffer size.
		*/
		SourceDataLine	line = null;
		DataLine.Info	info = new DataLine.Info(SourceDataLine.class,
							 audioFormat);
		try
 		{
			line = (SourceDataLine) AudioSystem.getLine(info);

			/*
			  The line is there, but it is not yet ready to
			  receive audio data. We have to open the line.
			*/
			line.open(audioFormat);
		} 
		catch (LineUnavailableException e)
 		{
			//e.printStackTrace();
			// sound blocked, possible and even likely
			// in linux. artsd or another program can block sound device
		} 
		catch (Exception e)
 		{
			//e.printStackTrace();
		} 

		/*
		  Still not enough. The line now can receive data,
		  but will not pass them on to the audio output device
		  (which means to your sound card). This has to be
		  activated.
		*/  
		line.start();

		/*
		  Ok, finally the line is prepared. Now comes the real
		  job: we have to write data to the line. We do this
		  in a loop. First, we read data from the
		  AudioInputStream to a buffer. Then, we write from
		  this buffer to the Line. This is done until the end
		  of the file is reached, which is detected by a
		  return value of -1 from the read method of the
		  AudioInputStream.
		*/  
		int	nBytesRead = 0;
		byte[]	abData = new byte[EXTERNAL_BUFFER_SIZE];
		while (nBytesRead != -1)
 		{
			try
			{
				nBytesRead = audioInputStream.read(abData, 0, abData.length);
			}
			catch (IOException e)
			{
				e.printStackTrace();
			}
			if (nBytesRead >= 0)
			{
				int	nBytesWritten = line.write(abData, 0, nBytesRead);
			}
		} 

		/*
		  Wait until all data are played.
		  This is only necessary because of the bug noted below.
		  (If we do not wait, we would interrupt the playback by
		  prematurely closing the line and exiting the VM.)
		 
		  Thanks to Margie Fitch for bringing me on the right
		  path to this solution.
		*/  
		line.drain();

		/*
		  All data are played. We can close the shop.
		*/  
		line.close();

	} 
}