使用 javax.sound.sampled.Clip 在游戏中播放、循环和停止多个声音。意外错误

Posted 2023-02-16

【中文标题】使用 javax.sound.sampled.Clip 在游戏中播放、循环和停止多个声音。意外错误

【英文标题】：Using javax.sound.sampled.Clip to play, loop, and stop multiple sounds in a game. Unexpected Errors

【发布时间】：2012-08-08 18:42:34

【问题描述】：

我试图在游戏中同时播放两种 wav 声音（背景音乐和效果）。我首先使用 java 中的另一个音频处理程序构建了这段代码，该处理程序将处理声音的播放、停止和循环。这个结构会播放背景音乐或效果，但一次只能播放一个。我环顾互联网，并被告知使用 javax.sound.sampled.Clip 来处理声音，因此重用了相同的构造（播放、停止、循环），但将其切换为使用 javax.sound.sampled.Clip。现在我完全迷路了。从我到目前为止所读的内容来看，我已经完成了所有正确的操作，并且在 Eclipse 编辑器中没有出现任何错误，但是当我运行它时，我得到了两个错误之一。在 Eclipse（在 Linux 上运行）中抛出了 LineUnavailableException。在 Eclipse（在 Windows 7 上运行）中，我在此代码的 loop() 部分中获得了 java.lang.NullPointerException。如果您能告诉我我做错了什么或指向我一些相关文档，我将不胜感激。我假设它与我的处理异常的代码有关，但我不确定。如果您发现任何其他可怕的代码错误，请告诉我，我正在努力成为我能做到的最好的程序员，并且非常感谢建设性的批评。感谢您的宝贵时间。

    import java.io.File;
    import java.io.IOException;
    import java.net.MalformedURLException;
    import javax.sound.sampled.AudioInputStream;
    import javax.sound.sampled.Audiosystem;
    import javax.sound.sampled.Clip;
    import javax.sound.sampled.LineUnavailableException;
    import javax.sound.sampled.UnsupportedAudioFileException;

    /**
     * Handles play, pause, and looping of sounds for the game.
     * @author Tyler Thomas
     *
     */
    public class Sound 
        private Clip myClip;
        public Sound(String fileName) 
                try 
                    File file = new File(fileName);
                    if (file.exists()) 
                        Clip myClip = AudioSystem.getClip();
                        AudioInputStream ais = AudioSystem.getAudioInputStream(file.toURI().toURL());
                        myClip.open(ais);
                    
                    else 
                        throw new RuntimeException("Sound: file not found: " + fileName);
                    
                
                catch (MalformedURLException e) 
                    throw new RuntimeException("Sound: Malformed URL: " + e);
                
                catch (UnsupportedAudioFileException e) 
                    throw new RuntimeException("Sound: Unsupported Audio File: " + e);
                
                catch (IOException e) 
                    throw new RuntimeException("Sound: Input/Output Error: " + e);
                
                catch (LineUnavailableException e) 
                    throw new RuntimeException("Sound: Line Unavailable: " + e);
                
        
        public void play()
            myClip.setFramePosition(0);  // Must always rewind!
            myClip.loop(0);
            myClip.start();
        
        public void loop()
            myClip.loop(Clip.LOOP_CONTINUOUSLY);
        
        public void stop()
            myClip.stop();
        
    

【参考方案1】：

我能够让代码正常工作，现在对 Clips 有了更好的理解。对我帮助最大的页面是http://www3.ntu.edu.sg/home/ehchua/programming/java/J8c_PlayingSound.html，它分解了所有内容并帮助我了解了我犯错的地方。这是我的最终工作代码。和以前一样，如果您在逻辑或风格上发现任何可怕的错误或过失，请告诉我。

import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.Clip;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.UnsupportedAudioFileException;

/**
 * Handles playing, stoping, and looping of sounds for the game.
 * @author Tyler Thomas
 *
 */
public class Sound 
    private Clip clip;
    public Sound(String fileName) 
        // specify the sound to play
        // (assuming the sound can be played by the audio system)
        // from a wave File
        try 
            File file = new File(fileName);
            if (file.exists()) 
                AudioInputStream sound = AudioSystem.getAudioInputStream(file);
             // load the sound into memory (a Clip)
                clip = AudioSystem.getClip();
                clip.open(sound);
            
            else 
                throw new RuntimeException("Sound: file not found: " + fileName);
            
        
        catch (MalformedURLException e) 
            e.printStackTrace();
            throw new RuntimeException("Sound: Malformed URL: " + e);
        
        catch (UnsupportedAudioFileException e) 
            e.printStackTrace();
            throw new RuntimeException("Sound: Unsupported Audio File: " + e);
        
        catch (IOException e) 
            e.printStackTrace();
            throw new RuntimeException("Sound: Input/Output Error: " + e);
        
        catch (LineUnavailableException e) 
            e.printStackTrace();
            throw new RuntimeException("Sound: Line Unavailable Exception Error: " + e);
        

    // play, stop, loop the sound clip
    
    public void play()
        clip.setFramePosition(0);  // Must always rewind!
        clip.start();
    
    public void loop()
        clip.loop(Clip.LOOP_CONTINUOUSLY);
    
    public void stop()
            clip.stop();
        
    

【讨论】：

您能否详细解释一下该链接，以防万一它出现故障？

【参考方案2】：

我发现了一种有用的技术来阻止声音。您可以将这两个类复制下来并自己进行测试。尽管如此，clip.stop() 方法更像是一种暂停方法。它会停止播放声音，是的，但它不会清除线路中的声音。结果，声音仍在排队播放，无法播放新声音。因此，使用 clip.close() 方法将清除此排队数据并允许播放新声音或执行其他操作。另请注意，在以下代码中，声音文件被放置在名为“predator.wav”的项目文件夹中，此声音可以是您想要使用的任何类型的声音，而不是我选择的声音，但请确保它是 .wav 格式并且声音必须位于项目文件夹的最顶层。

/*
 * File: KeyMap.java
 * Author: Andrew Peturis Chaselyn Langley; UAB EE Students
 * Assignment:  SoundBox - EE333 Fall 2015
 * Vers: 1.0.0 10/20/2015 agp - initial coding
 *
 * Credits: Dr. Green, UAB EE Engineering Professor
 */

import java.io.File;
import java.io.IOException;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.Clip;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.UnsupportedAudioFileException;

public class KeyMap 

    private char keyCode;
    private String song;
    private Clip clip;

    // Don't allow default constructor
    private KeyMap() 
    

    public KeyMap(char keyCode, String song) throws LineUnavailableException 
        this.keyCode = keyCode;
        this.song = song;

        // Create an audiostream from the inputstream
        clip = AudioSystem.getClip();
    

    public boolean match(char key) 
        return key == keyCode;
    

    // Play a sound using javax.sound and Clip interface
    public String play() 
        try 
            // Open a sound file stored in the project folder
            clip.open(AudioSystem.getAudioInputStream(new File(song + ".wav")));

            // Play the audio clip with the audioplayer class
            clip.start();

            // Create a sleep time of 2 seconds to prevent any action from occuring for the first
            // 2 seconds of the sound playing
            Thread.sleep(2000);

         catch (LineUnavailableException | UnsupportedAudioFileException | IOException | InterruptedException e) 
            System.out.println("Things did not go well");
            System.exit(-1);
        
        return song;
    

    // Stop a sound from playing and clear out the line to play another sound if need be.
    public void stop() 
        // clip.stop() will only pause the sound and still leave the sound in the line
        // waiting to be continued. It does not actually clear the line so a new action could be performed.
        clip.stop();

        // clip.close(); will clear out the line and allow a new sound to play. clip.flush() was not 
        // used because it can only flush out a line of data already performed.
        clip.close();
    

---

/*
 * File: SoundBox.java
 * Author: Andrew Peturis, Chaselyn Langley; UAB EE Students
 * Assignment:  GUI SoundBox - EE333 Fall 2015
 * Vers: 1.0.0 09/08/2015 agp - initial coding
 */

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Scanner;
import javax.sound.sampled.LineUnavailableException;

/**
 *
 * @author Andrew Peturis, Chaselyn Langley
 *
 */
public class SoundBox 

    static Scanner scanner = new Scanner(System.in);   //Scanner object to read user input
    InputStream input;

    /**
     * @param args the command line arguments
     * @throws java.io.IOException
     */
    public static void main(String[] args) throws IOException, LineUnavailableException 

        String line;
        Character firstChar;
        String predator = "predator";
        String explosion = "explosion";

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        KeyMap[] keyedSongs = 
            new KeyMap('a', predator),;

        while (true) 
            line = br.readLine();
            firstChar = line.charAt(0);

            for (int i = 0; i < keyedSongs.length; i++) 
                if (keyedSongs[i].match(firstChar)) 

                    // Notice now by running the code, after the first second of sleep time the sound can
                    // and another sound can be played in its place
                    keyedSongs[i].stop();
                    System.out.println("Played the sound: " + keyedSongs[i].play());
                    break;
                
            

            if (firstChar == 'q') 
                break;