在从 Intellij IDEA 创建的 jar 文件中播放 .wav 时遇到问题

Question

Apologies if this has been asked before, but I was unable to find an answer that worked for us. I am also a beginner so please bear with me.

Essentially, after jarring our code the audio stopped working.

clip = AudioSystem.getClip();
             File file = new File(musicLocation);
             clip.open(AudioSystem.getAudioInputStream(file.getAbsoluteFile()));
             clip.start();

I have tried using getResourceAsStream and getResource as apparently files don't work properly when jarred but it still does not work even in Intellij.

My code is located in the src folder and the music location is being passed to the code like so:

filepath = "src/Images/music/click.wav"; 
musicObject.playMusic(filepath);

Images are working properly in the jar file.

Edit: it appear that the jar file is unable to take the audio files, which are within another folder that is otherwise being accessed, because the file size of the jar does not change after the deletion of the.wav files.

Edit 2:

public class Music {
    Clip loop;
    void loopMusic(String musicLocation) {
        try {
            loop = AudioSystem.getClip();
            InputStream is = getClass().getResourceAsStream(musicLocation);
            AudioInputStream audioS = AudioSystem.getAudioInputStream(is);
            loop = AudioSystem.getClip();
            loop.open(audioS);
            loop.start();
            loop.loop(Clip.LOOP_CONTINUOUSLY);
        } catch (Exception e) {
            System.out.println(e);
        }
    }
    void stopLoop(){
        if (loop != null) {
            loop.stop();
            loop.close();
        }
        loop=null;
    }
}

This is the coe we are attempting to use. The musicLocation String is passed in the format of: /folder/file.wav After manually putting the.wav files into the jar through winrar, it still is unable to load the music in the jar file.

Edit 3:Attempting to use URL Class, receiving NullPointerException

URL musicLocation = this.getClass().getResource("/Images/music/battle.wav");
AudioInputStream inputStream = AudioSystem.getAudioInputStream(musicLocation);

When passed into the AudioInputStream as a file with the "src" before the location name, it does not pass a null.

Edit 4: Attempting to use URL Class with the file inside of folder in Music class package

URL musicLocation = this.getClass().getResource("audio/battle.wav");
AudioInputStream inputStream = AudioSystem.getAudioInputStream(musicLocation);

With the audio folder above being inside the classes (containing all the.java files) package, this returns a NullPointerException. After adding a "Classes/" to the front, hovering over the string in my IDE allows me to "see" that the file is correctly being sourced if you will but it still returns a NullPointerException to the.wav file.

Edit 5: Receiving this error after implementing Phil's code

Exception in thread "main" java.lang.ExceptionInInitializerError
    at Classes.Frame.<init>(Frame.java:15)
    at Classes.GraphicsRunner.main(GraphicsRunner.java:15)
Caused by: java.lang.NullPointerException
    at java.base/java.util.Objects.requireNonNull(Objects.java:222)
    at java.desktop/javax.sound.sampled.AudioSystem.getAudioInputStream(AudioSystem.java:1032)
    at Classes.Music.<init>(Music.java:16)
    at Classes.Panel.<clinit>(Panel.java:24)
    ... 2 more

Edit 6: Displaying class that resulted in error above

package Classes;

import javax.sound.sampled.*;
import javax.swing.*;
import java.io.*;
import java.net.URL;

public class Music {
    Clip clip;

    // Constructor, create looping audio resource, hold in memory.
    public Music() {
        URL url = this.getClass().getResource("audio/battle.wav");
        AudioInputStream ais;
        try {
            ais = AudioSystem.getAudioInputStream(url);
            //line 16 above 
            DataLine.Info info = new DataLine.Info(Clip.class, ais.getFormat());
            clip = (Clip) AudioSystem.getLine(info);
            clip.open(ais);
        } catch (UnsupportedAudioFileException | IOException | LineUnavailableException e) {
            e.printStackTrace();
        }
    }

    public void play() {
        clip.setFramePosition(0);
        clip.loop(Clip.LOOP_CONTINUOUSLY);
    }
}

Edit 7: Phils identical set of code worked upon moving project to Eclipse. I'm still unsure of why it didn't work in Intellij but my problem was solved n.netheless. Thanks to everyone who offered their help!

Answer 1

The java.io.File object is not a good choice for addressing files that are packed in jars. I don't know the correct technical way to explain this, but in simple language, it can only address files that are in file folders. It has no ability to "see" within jar files.

For this reason, it's more usual to access the file by getting its URL using the Class.getResource method. A URL can identify a file that has been compressed and is located within a jar.

It is also possible to address and load a sound file in a jar using the .getResourceAsStream method. This method returns an InputStream , not a URL . But this is a dicier option. If you look at the API for the overloaded AudioSystem.getAudioInputStream , and compare the versions, you'll see that if the argument is an InputStream , the file will be subjected to tests to determine if "mark" and "reset" are supported. A sizable number of audio files fail these tests. For this reason, it's safer to use the method with a URL argument.

Problems can also arise in how the file name is provide in the getResource method, but usually if the name String works in the DAW it will also work in a jar (assuming you are obtaining a URL and not a File). The specifics about "relative" and "root" addressing aren't the easiest to explain. But we can go there if needed.

EDIT: Code example for troubleshooting.

public class Music {
    Clip clip;

    // Constructor, create looping audio resource, hold in memory.
    public Music() {
        URL url = this.getClass().getResource("audio/battle.wav");
        AudioInputStream ais;
        try {
            ais = AudioSystem.getAudioInputStream(url);
            DataLine.Info info = new DataLine.Info(Clip.class, ais.getFormat());
            clip = (Clip) AudioSystem.getLine(info);
            clip.open(ais);
        } catch (UnsupportedAudioFileException | IOException | LineUnavailableException e) {
            e.printStackTrace();
        }
    }

    public void play() {
        clip.setFramePosition(0);
        clip.loop(Clip.LOOP_CONTINUOUSLY);
    }    
}

The code assumes the following file folder structure:

/src/.../folderwithMusic/Music
/src/.../folderwithMusic/audio/battle.wav

Note that the file name is case sensitive. A null value for the URL indicates that the file is not at the expected location. First get this working in your IDE, and maybe prefer either your console or File Explorer to verify the file structure and file location.

If you try running the above and have problems, the exact code as entered and stack trace would be helpful.