我已经设置了我的 netbeans 项目所需的运行时库。但是当我尝试播放 mp3 文件时mp3plugin.jar仍然得到上述内容。这是什么原因：exception
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;
public class tester_1 {
private static final int EXTERNAL_BUFFER_SIZE = 128000;
public static void main(String[] args)
{
/*
We check that there is exactely one command-line
argument.
If not, we display the usage message and exit.
*/
/*
Now, that we're shure there is an argument, we
take it as the filename of the soundfile
we want to play.
*/
String strFilename = "mp3tester.mp3";
File soundFile = new File("mp3tester.mp3");
/*
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();
System.exit(1);
}
/*
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();
System.exit(1);
}
catch (Exception e)
{
e.printStackTrace();
System.exit(1);
}
/*
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();
/*
There is a bug in the jdk1.3/1.4.
It prevents correct termination of the VM.
So we have to exit ourselves.
*/
System.exit(0);
}
private static void printUsageAndExit()
{
out("tester_1: usage:");
out("\tjava tester_1 <soundfile>");
System.exit(1);
}
private static void out(String strMessage)
{
System.out.println(strMessage);
}
}
当我运行这个程序时，我得到以下异常：
java.lang.IllegalArgumentException: No line matching interface SourceDataLine supporting format MPEG1L3 44100.0 Hz, unknown bits per sample, stereo, unknown frame size, unknown frame rate, is supported.
at javax.sound.sampled.AudioSystem.getLine(AudioSystem.java:476)
at mp3tester_mp3plugin.tester_1.main(tester_1.java:178)
Java Result: 1
我收到此错误的原因是什么？