java - "file", "localhost"在这个程序的构造函数中是什么意思？

Question

这似乎是一个愚蠢的问题，但是，在这段代码中我试图制作一个点唱机 GUI。它使用组合框来选择 6 首歌曲。我将 .wav 歌曲文件的副本存储在我的 Music 文件夹和 JukeBox.java 程序所在的文件夹中。我猜“file”是文件名，“localhost”是路径名？无论如何，它目前给我这个错误: - 我将在下面发布完整的程序....

craig@craig-laptop:~/Documents/panda/newGUI$ java JukeBox
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at com.sun.media.sound.JavaSoundAudioClip.readStream(JavaSoundAudioClip.java:345)
    at com.sun.media.sound.JavaSoundAudioClip.loadAudioData(JavaSoundAudioClip.java:324)
    at com.sun.media.sound.JavaSoundAudioClip.<init>(JavaSoundAudioClip.java:110)
    at sun.applet.AppletAudioClip.createAppletAudioClip(AppletAudioClip.java:125)
    at sun.applet.AppletAudioClip.<init>(AppletAudioClip.java:66)
    at java.applet.Applet.newAudioClip(Applet.java:311)
    at JukeBoxControls.<init>(JukeBox.java:36)
    at JukeBox.main(JukeBox.java:113)

//JukeBox.java

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.applet.AudioClip;
import java.net.URL;

class JukeBoxControls extends JPanel  {

  private JComboBox musicCombo;
  private JButton stopButton, playButton;
  private AudioClip[] music;
  private AudioClip current;

  //constructor
  public JukeBoxControls ()  { 
   URL url1, url2,  url3, url4, url5, url6;
   url1 = url2 = url3 = url4 = url5 = url6 = null;

  //obtain and store the audio clips
  try  {
    url1 = new URL ("file", "localhost", "booradleys.wav");
    url2 = new URL ("file", "localhost", "notobig.wav");
    url3 = new URL ("file", "localhost", "roots.wav");
    url4 = new URL ("file", "localhost", "snakadaktal.wav");
    url5 = new URL ("file", "localhost", "sumthing.wav");
    url6 = new URL ("file", "localhost", "radiocontrol.wav");
  }
  catch (Exception exception) {}

  music = new AudioClip[7];
  music[0] = null; //corresponds to 'make a selection'
  music[1] = JApplet.newAudioClip (url1);
  music[2] = JApplet.newAudioClip (url2);
  music[3] = JApplet.newAudioClip (url3);
  music[4] = JApplet.newAudioClip (url4);
  music[5] = JApplet.newAudioClip (url5);
  music[6] = JApplet.newAudioClip (url6);

  JLabel titleLabel = new JLabel ("Java Juke Box");
  titleLabel.setAlignmentX (Component.CENTER_ALIGNMENT);

  //create the list of strings for combo box
  String[] musicNames = {"Make a selection...", "booradleys", "notobig",
                         "roots", "snakadaktal", "sumthing"};
  JComboBox <String> musicCombo = new JComboBox<> (musicNames);
  musicCombo.setAlignmentX (Component.CENTER_ALIGNMENT);

  //set up the buttons
  playButton = new JButton ("Play", new ImageIcon ("play.gif"));
  playButton.setBackground (Color.white);
  playButton.setMnemonic ('p');
  stopButton = new JButton ("Stop", new ImageIcon ("stop.gif"));
  stopButton.setBackground (Color.white);
  stopButton.setMnemonic ('s');

  JPanel buttons = new JPanel();
  buttons.setLayout (new BoxLayout (buttons, BoxLayout.X_AXIS));
  buttons.add (playButton);
  buttons.add (Box.createRigidArea (new Dimension(5, 0)));
  buttons.add (stopButton);
  buttons.setBackground (Color.cyan);

  //set up this panel
  setPreferredSize (new Dimension (300, 100));
  setBackground (Color.cyan);
  setLayout (new BoxLayout (this, BoxLayout.Y_AXIS));
  add (Box.createRigidArea (new Dimension(0, 5)));
  add (titleLabel);
  add (Box.createRigidArea (new Dimension(0, 5)));
  add (musicCombo);
  add (Box.createRigidArea (new Dimension(0, 5)));
  add (buttons);
  add (Box.createRigidArea (new Dimension(0, 5)));

  musicCombo.addActionListener (new ComboListener());
  stopButton.addActionListener (new ButtonListener());
  playButton.addActionListener (new ButtonListener());

  current = null;
  }

  //represents the action listener for combo box
  private class ComboListener implements ActionListener  {

   public void actionPerformed (ActionEvent event)  {
    if (current != null)
        current.stop();

    current = music[musicCombo.getSelectedIndex()];
    }
  }

  private class ButtonListener implements ActionListener  {

    public void actionPerformed (ActionEvent event)  {
      if (current != null)
        current.stop();
      if (event.getSource() == playButton)
        if (current != null)
            current.play();
    }
  }
}


public class JukeBox  {

  public static void main (String[] args)  {
    JFrame frame = new JFrame ("Java Juke Box");
    frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
    JukeBoxControls controlPanel = new JukeBoxControls();
    frame.getContentPane().add(controlPanel);
    frame.pack();
    frame.setVisible(true);
  }
}

Answer 1

关于构造函数，它构造一个 URL，如下所示:

url1 = new URL ("file", "localhost", "booradleys.wav");

几乎肯定会给您 URL:

file://localhost/booradleys.wav

该错误表明您的内存不足，因此您需要找出导致该问题的原因。我会删除 URL 和音频剪辑(减少到一两个)，看看这是否是问题所在，然后尝试使用可能更有效的格式(例如 MP3)或增加运行时环境可用的内存。