程序完全在Eclipse中运行，但是当导出为可运行的JAR文件时无法运行

Question

I have a main class that looks like this:

package complete;

import java.io.File;
import java.io.*;
import javax.sound.sampled.*;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.BooleanControl;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.FloatControl;
import javax.sound.sampled.SourceDataLine;
import javax.swing.JFrame;

public class Main {

public static void main(String[] args) {
    JFrame frame = new JFrame("Presentation");
    frame.setSize(806, 506);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setResizable(false);
    frame.add(new GameFrame());
    frame.setVisible(true);
sound = new File("Assets/BackgroundSound.wav"); // Write you own file location here and be aware that it need to be an .wav file

    new Thread(play).start();
}

static File sound;
static boolean muted = false; // This should explain itself
static float volume = 100.0f; // This is the volume that goes from 0 to 100
static float pan = 0.0f; // The balance between the speakers 0 is both sides and it goes from -1 to 1

static double seconds = 0.0d; // The amount of seconds to wait before the sound starts playing

static boolean looped_forever = true; // It will keep looping forever if this is true

static int loop_times = 0; // Set the amount of extra times you want the sound to loop (you don't need to have looped_forever set to true)
static int loops_done = 0; // When the program is running this is counting the times the sound has looped so it knows when to stop

final static Runnable play = new Runnable() // This Thread/Runnabe is for playing the sound
{
    public void run()
    {
        try
        {
            // Check if the audio file is a .wav file
            if (sound.getName().toLowerCase().contains(".wav"))
            {
                AudioInputStream stream = AudioSystem.getAudioInputStream(sound);

                AudioFormat format = stream.getFormat();

                if (format.getEncoding() != AudioFormat.Encoding.PCM_SIGNED)
                {
                    format = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED,
                            format.getSampleRate(),
                            format.getSampleSizeInBits() * 2,
                            format.getChannels(),
                            format.getFrameSize() * 2,
                            format.getFrameRate(),
                            true);

                    stream = AudioSystem.getAudioInputStream(format, stream);
                }

                SourceDataLine.Info info = new DataLine.Info(
                        SourceDataLine.class,
                        stream.getFormat(),
                        (int) (stream.getFrameLength() * format.getFrameSize()));

                SourceDataLine line = (SourceDataLine) AudioSystem.getLine(info);
                line.open(stream.getFormat());
                line.start();

                // Set Volume
                FloatControl volume_control = (FloatControl) line.getControl(FloatControl.Type.MASTER_GAIN);
                volume_control.setValue((float) (Math.log(volume / 100.0f) / Math.log(10.0f) * 20.0f));

                // Mute
                BooleanControl mute_control = (BooleanControl) line.getControl(BooleanControl.Type.MUTE);
                mute_control.setValue(muted);

                FloatControl pan_control = (FloatControl) line.getControl(FloatControl.Type.PAN);
                pan_control.setValue(pan);

                long last_update = System.currentTimeMillis();
                double since_last_update = (System.currentTimeMillis() - last_update) / 1000.0d;

                // Wait the amount of seconds set before continuing
                while (since_last_update < seconds)
                {
                    since_last_update = (System.currentTimeMillis() - last_update) / 1000.0d;
                }

                //System.out.println("Playing!");

                int num_read = 0;
                byte[] buf = new byte[line.getBufferSize()];

                while ((num_read = stream.read(buf, 0, buf.length)) >= 0)
                {
                    int offset = 0;

                    while (offset < num_read)
                    {
                        offset += line.write(buf, offset, num_read - offset);
                    }
                }

                line.drain();
                line.stop();

                if (looped_forever)
                {
                    new Thread(play).start();
                }
                else if (loops_done < loop_times)
                {
                    loops_done++;
                    new Thread(play).start();
                }
            }
        }
        catch (Exception ex) { ex.printStackTrace(); }
    }
};



}

When I run the runnable JAR, the frame opens with the correct size and title but with a blank screen.

When I run from the command line I get this error:

java.io.FileNotFoundException: Assets\BackgroundSound.wav <The system cannot find the path specified> 

at java.io.FileInputStream.open<Native Method>

at java.io.FileInputStream.<init><Unknown Source>

at com.sun.media.sound.WaveFloatFileReader.getAudioInputStream<Unknown Source>

at javax.sound.sampled.AudioSystem.getAudioInputStream<Unknown Source>

at complete.Main$1.run<Main.Java:50>

at java.lang.Thread.run<Unknown Source>

I have extracted the files from the JAR and all the classes, images and the WAV file are there.

When I remove the sound section from the Main class and run in Eclipse, the program runs completely and without sound as expected.

When I export this version as a Runnable JAR, the same thing happens as before when I attempted to run it, except this time there are no command line errors.

Answer 1

要从jar中加载文件，您需要使用getResources或getResourceAsStream。

Answer 2

采用：

sound = new File(Main.class.getResource("Assets/BackgroundSound.wav").getPath());

Answer 3

The data for sound is not contained in a file on your disk directly; it is inside the jar file for your project. So, using File to access it is incorrect. Instead, use the overloaded AudioStream method:

public static AudioInputStream getAudioInputStream(InputStream stream)
                                        throws UnsupportedAudioFileException,
                                               IOException

Obtains an audio input stream from the provided input stream. The stream must point to valid audio file data. The implementation of this method may require multiple parsers to examine the stream to determine whether they support it. These parsers must be able to mark the stream, read enough data to determine whether they support the stream, and, if not, reset the stream's read pointer to its original position. If the input stream does not support these operation, this method may fail with an IOException.

You get the InputStream by using Class.getResourceAsStream(String name) . That will look on the class path, and so can be set to work in both Eclipse and from a jar file. Easiest is to move the sound file to be alongside your class file, so you can just use:

InputStream soundResource = Main.class.getResourceAsStream("BackgroundSound.wav");
AudioInputStream ais = AudioSystem.getAudioInputStream(soundResource);

Sorry--I needed to edit the last part--I forgot that this was all in main . Try not to do that for any but the most trivial programs. Instead, instantiate the class and have the instance do things. And rename the class from Main to something like SoundDemo . Otherwise in three months you'll say to yourself, "Where did I do that exercise on learning how to have Java play sounds? What file was it in? It was in Main ? Really?"