本人想用几个JPanel的来重复合成一个图画,就是说,可以几层的JPanel来重叠在一起,然后想通过setOpaque的方法来设置每一个JPanel透明,想显示各个JPanel的图像,但是不行,请问怎样可以做到呢?

自己覆写JPanel的paintComponent方法,用Graphics的drawImage方法自己draw上去.

示例程序:

import java.io.*;
import java.awt.*;
import javax.swing.*;
import javax.imageio.*;

/**
*author: [url=http://eastsun.javaeye.com]Eastsun[/url]
*/
public class CompositeImage extends JFrame{
    Image backImage,foreImage;
    public CompositeImage(){
        super(\"CompositeImage\");
        try{
            backImage =ImageIO.read(new File(\"back.jpg\"));
            foreImage =ImageIO.read(new File(\"fore.jpg\"));
        }catch(IOException e){
            e.printStackTrace();
            System.exit(1);
        }
        JPanel panel =new JPanel(){
            public void paintComponent(Graphics g){
                Graphics2D g2 =(Graphics2D)g;
                g2.drawImage(backImage,0,0,null);
                g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,0.3f));
                g2.drawImage(foreImage,80,120,null);
            }
        };
        Dimension dim =new Dimension(backImage.getWidth(null),backImage.getHeight(null));
        panel.setPreferredSize(dim);
        add(panel);
        pack();
        setResizable(false);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }
    public static void main(String[] args){
        SwingUtilities.invokeLater(new Runnable(){
            public void run(){
                new CompositeImage().setVisible(true);
            }
        });
    }
}

068IJQxR.rar (28.88 KB) 关于JPanel 的setOpaque问题

我把那代码放到Jcreater环境里去运行了下，编译通过，运行就出现了异常，说:Can not read input file!
是什么原因？