jukeboxcontrols.java

Java 程序设计教程（第五版）EXAMPLESchap10源码

//********************************************************************
//  JukeBoxControls.java       Author: Lewis and Loftus
//
//  Represents the control panel for the juke box.
//********************************************************************

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

public class JukeBoxControls extends JPanel
{
   private JComboBox musicCombo;
   private JButton stopButton, playButton;
   private AudioClip[] music;
   private AudioClip current;

   //-----------------------------------------------------------------
   //  Sets up the GUI for the juke box.
   //-----------------------------------------------------------------
   public JukeBoxControls()
   {
      URL url1, url2, url3, url4, url5, url6;
      url1 = url2 = url3 = url4 = url5 = url6 = null;

      // Obtain and store the audio clips to play
      try
      {
         url1 = new URL ("file", "localhost", "westernBeat.wav");
         url2 = new URL ("file", "localhost", "classical.wav");
         url3 = new URL ("file", "localhost", "jeopardy.au");
         url4 = new URL ("file", "localhost", "newAgeRythm.wav");
         url5 = new URL ("file", "localhost", "eightiesJam.wav");
         url6 = new URL ("file", "localhost", "hitchcock.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 the combo box options
      String[] musicNames = {"Make A Selection...", "Western Beat",
               "Classical Melody", "Jeopardy Theme", "New Age Rythm",
               "Eighties Jam", "Alfred Hitchcock's Theme"};

      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 the combo box.
   //*****************************************************************
   private class ComboListener implements ActionListener
   {
      //--------------------------------------------------------------
      //  Stops playing the current selection (if any) and resets
      //  the current selection to the one chosen.
      //--------------------------------------------------------------
      public void actionPerformed (ActionEvent event)
      {
         if (current != null)
            current.stop();

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

   //*****************************************************************
   //  Represents the action listener for both control buttons.
   //*****************************************************************
   private class ButtonListener implements ActionListener
   {
      //--------------------------------------------------------------
      //  Stops the current selection (if any) in either case. If
      //  the play button was pressed, start playing it again.
      //--------------------------------------------------------------
      public void actionPerformed (ActionEvent event)
      {
         if (current != null)
            current.stop();

         if (event.getSource() == playButton)
            if (current != null)
               current.play();
      }
   }
}