sogui wrote:
我自己继承了一个JDesktopPane的MyJDesktopPane的类，可以实现设置背景图片，现在的问题是在一个MDI窗体中打开的子窗体沉在JDesktopPane下面，不可见！向各位请教有什么好的办法解决这个问题？
我的代码如下：

package jbtest;
import javax.swing.*;
import java.awt.*;
//import java.awt.Canvas;

/**
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2004</p>
 * <p>Company: </p>
 * @author not attributable
 * @version 1.0
 */

public class MyJDesktopPane extends JDesktopPane {
  Canvas mycanvas;
  public MyJDesktopPane() {
  }
public void paint(Graphics g){
    ImageIcon myimage=new ImageIcon(jbtest.Frame1.class.getResource("Windows 2000.jpg"));
    Image image=myimage.getImage();
    g.drawImage(image,0,0,this.getSize().width,this.getSize().height,myimage.getImageObserver());

  }
}

/*
 * Created on 2005/3/8
 */
package com.jsptw.j2se;

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;

import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;

public class WPDesktop extends JDesktopPane {
  private Image wallPaper;

  public static void main(String[] args)
  {
    Image bg = Toolkit.getDefaultToolkit().createImage(
      WPDesktop.class.getResource("images/risako.jpg"));
    JDesktopPane desktop = new WPDesktop(bg);
    
    JInternalFrame childFrame = new JInternalFrame("MDI child frame", true);
    childFrame.setBounds(100, 100, 200, 200);
    desktop.add(childFrame, new Integer(10));
    childFrame.show();

    JFrame mainFrame = new JFrame("Application main frame");
    mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    mainFrame.getContentPane().add(desktop);
    mainFrame.pack();
    mainFrame.show();
  }
  public WPDesktop(Image wallPaper)
  {
    this.wallPaper = wallPaper;
    MediaTracker tracker = new MediaTracker(this);
    tracker.addImage(wallPaper, 0);
    try {
      tracker.waitForAll();
    }
    catch (InterruptedException e) {
      e.printStackTrace();
    }
  }

  protected void paintComponent(Graphics g)
  {
    super.paintComponent(g);
    
    int width = wallPaper.getWidth(this);
    int height = wallPaper.getHeight(this);
    Dimension size = getSize();
    
    // paint tiled wall paper
    for (int x = 0; x < size.width; x += width)
      for (int y = 0; y < size.height; y += height)
        g.drawImage(wallPaper, x, y, this);
  }
  
  public Dimension getPreferredSize()
  {
    return new Dimension(wallPaper.getWidth(this), wallPaper.getHeight(this));
  }
}

package com.jsptw.j2se;

import java.awt.Container;
import java.awt.Dimension;
import java.awt.HeadlessException;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;

import javax.swing.ImageIcon;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class DesktopDemo extends JFrame {

  public static void main(String[] args)
  {
    Image bgImage = Toolkit.getDefaultToolkit().createImage(DesktopDemo.class.getResource(
        "images/lavigne_avril_005.jpg"));
    JFrame frm = new DesktopDemo(bgImage);
    frm.setTitle("A MDI Frame with a image as background.");
    frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frm.pack();
    frm.show();
  }

  public DesktopDemo(Image image) throws HeadlessException
  {
    super(image.toString());

    _bgImage = image;
    initComponsnts();
  }

  public Container getContentPane()
  {
    return _content;
  }
  
  private void initComponsnts()
  {
    JDesktopPane desk = new JDesktopPane() {
      public Dimension getPreferredSize()
      {
        return _bgView.getPreferredSize();
      }
    };
    _bgView = new JLabel(new ImageIcon(_bgImage), JLabel.CENTER);
    _bgView.setOpaque(true);

    _content = (JPanel) super.getContentPane();
    _content.setOpaque(false);
    desk.add(_content, JDesktopPane.FRAME_CONTENT_LAYER);
    
    desk.add(
      _bgView,
      new Integer(JDesktopPane.FRAME_CONTENT_LAYER.intValue() - 1));
    
    desk.addComponentListener(new ComponentAdapter(){
      public void componentResized(ComponentEvent e)
      {
        Dimension size = e.getComponent().getSize();
        _bgView.setSize(size);
        _content.setSize(size);
        _content.revalidate();
      }
    });
    setContentPane(desk);

    JInternalFrame dummy1 =
      new JInternalFrame("Dummy frame A", true, true, true, true);
    dummy1.setBounds(100, 100, 300, 200);
    desk.add(dummy1, JDesktopPane.DEFAULT_LAYER);
    dummy1.show();

    JInternalFrame dummy2 = new JInternalFrame("Dummy frame B", true, true);
    dummy2.setBounds(200, 200, 400, 300);
    desk.add(dummy2, JDesktopPane.DEFAULT_LAYER);
    dummy2.show();
  }

  private Image _bgImage;
  private JLabel _bgView;
  private JPanel _content;
}