JPanels 和播放音乐

Question

我有一个在 JFrame 中有多个 JPanel 的程序。在某些时候，只有一个面板可见 [setVisible(true)]，而其他所有面板不可见 [setVisible(false)]。我想要的是在 JPanel 可见时播放一段音乐，但在不可见时暂停。我有一个播放音频的类

public class AudioPlay extends Thread { 

private String filename;
private Position curPosition;

private final int EXTERNAL_BUFFER_SIZE = 524288; // 128Kb 

enum Position { 
    LEFT, RIGHT, NORMAL
};

public AudioPlay(String wavfile) { 
    filename = wavfile;
    curPosition = Position.NORMAL;
} 

public AudioPlay(String wavfile, Position p) { 
    filename = wavfile;
    curPosition = p;
} 

public void run() { 
    while(true){
        File soundFile = new File(filename);
        if (!soundFile.exists()) { 
            System.err.println("Wave file not found: " + filename);
            return;
        } 

        AudioInputStream audioInputStream = null;
        try { 
            audioInputStream = AudioSystem.getAudioInputStream(soundFile);
        } catch (UnsupportedAudioFileException e1) { 
            e1.printStackTrace();
            return;
        } catch (IOException e1) { 
            e1.printStackTrace();
            return;
        } 

        AudioFormat format = audioInputStream.getFormat();
        SourceDataLine auline = null;
        DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);

        try { 
            auline = (SourceDataLine) AudioSystem.getLine(info);
            auline.open(format);
        } catch (LineUnavailableException e) { 
            e.printStackTrace();
            return;
        } catch (Exception e) { 
            e.printStackTrace();
            return;
        } 

        if (auline.isControlSupported(FloatControl.Type.PAN)) { 
            FloatControl pan = (FloatControl) auline
                    .getControl(FloatControl.Type.PAN);
            if (curPosition == Position.RIGHT) 
                pan.setValue(1.0f);
            else if (curPosition == Position.LEFT) 
                pan.setValue(-1.0f);
        } 

        auline.start();
        int nBytesRead = 0;
        byte[] abData = new byte[EXTERNAL_BUFFER_SIZE];

        try { 
            while (nBytesRead != -1) { 
                nBytesRead = audioInputStream.read(abData, 0, abData.length);
                if (nBytesRead >= 0) 
                    auline.write(abData, 0, nBytesRead);
            } 
        } catch (IOException e) { 
            e.printStackTrace();
            return;
        } finally { 
            auline.drain();
            auline.close();
        }
    }
}

}

所以在每个类中都扩展了一个 JPanel 并有一个 AudioPlay 作为参数。首次创建 JPanel 时调用 start() 方法。但后来我一直在播放所有的音频文件。

谁能给我看一个 JPanel，它会在 JPanel 不可见时暂停其中一个 AudioPlay 类的 start() 方法？

编辑

好的，所以我有了一个想法并玩了一下，现在我可以让它仅在音频可见时播放！在其可见性关闭后，它会播放之前的面板音乐一两秒钟，但大多数情况下是做它应该做的！对于任何需要它的人，这里是更新的。

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.FloatControl; 
import javax.sound.sampled.LineUnavailableException; 
import javax.sound.sampled.SourceDataLine; 
import javax.sound.sampled.UnsupportedAudioFileException; 
import javax.swing.JPanel;

public class AudioPlay extends Thread { 

private String filename;
private Position curPosition;
JPanel panel;

private final int EXTERNAL_BUFFER_SIZE = 524288; // 128Kb 

enum Position { 
    LEFT, RIGHT, NORMAL
};

public AudioPlay(String wavfile, JPanel panel) { 
    filename = wavfile;
    curPosition = Position.NORMAL;
    this.panel = panel;
} 

public AudioPlay(String wavfile, Position p, JPanel panel) { 
    filename = wavfile;
    curPosition = p;
    this.panel = panel;
} 

public void run() { 
    while(true){
        File soundFile = new File(filename);
        if (!soundFile.exists()) { 
            System.err.println("Wave file not found: " + filename);
            return;
        } 

        AudioInputStream audioInputStream = null;
        try { 
            audioInputStream = AudioSystem.getAudioInputStream(soundFile);
        } catch (UnsupportedAudioFileException e1) { 
            e1.printStackTrace();
            return;
        } catch (IOException e1) { 
            e1.printStackTrace();
            return;
        } 

        AudioFormat format = audioInputStream.getFormat();
        SourceDataLine auline = null;
        DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);

        try { 
            auline = (SourceDataLine) AudioSystem.getLine(info);
            auline.open(format);
        } catch (LineUnavailableException e) { 
            e.printStackTrace();
            return;
        } catch (Exception e) { 
            e.printStackTrace();
            return;
        } 

        if (auline.isControlSupported(FloatControl.Type.PAN)) { 
            FloatControl pan = (FloatControl) auline
                    .getControl(FloatControl.Type.PAN);
            if (curPosition == Position.RIGHT) 
                pan.setValue(1.0f);
            else if (curPosition == Position.LEFT) 
                pan.setValue(-1.0f);
        } 

        auline.start();
        int nBytesRead = 0;
        byte[] abData = new byte[EXTERNAL_BUFFER_SIZE];
        try { 
            while (nBytesRead != -1) { 
                if(this.panel.isShowing()){
                    nBytesRead = audioInputStream.read(abData, 0, abData.length);
                    if (nBytesRead >= 0) 
                        auline.write(abData, 0, nBytesRead);
                }
            } 
        } catch (IOException e) { 
            e.printStackTrace();
            return;
        } finally { 
            auline.drain();
            auline.close();
        }
    }
}

}

Answer 1

你可以试试ComponentListener，虽然它对我没有用