Java JPanel_Bg设置背景

[java]
package com.han;

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

/**
* The result is :
* <p>
* If you use pack(), use the setPref() method when you want to resize
* components; If you do not use the Layout Manager, employ the combined
* methods: setLayout(null) + Components.setBounds()
*
* @author HAN
*
*/
@SuppressWarnings("serial")
public class JPanelTest extends JFrame {
    static JPanel panel;
    static JButton button;
    int BgImageWidth;
    int BgImageHeight;

    public JPanelTest() {
        // TODO Auto-generated constructor stub
        Container c = getContentPane();
        final Image img = Toolkit.getDefaultToolkit().getImage(
                JPanelTest.class.getResource("/images/Luxun.jpg"));
        BgImageWidth = img.getWidth(this);
        BgImageHeight = img.getHeight(this);
        panel = new JPanel() {
            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g); // paints the component's background, since this component is opaque
                Graphics2D g2 = (Graphics2D) g;
                g2.drawImage(img, 0, 0, BgImageWidth, BgImageHeight, this);
            }
        };
        c.add(panel, BorderLayout.CENTER);
        // panel.setPreferredSize(new Dimension(200, 250));
        System.out.println(panel.getPreferredSize());
        System.out.println(panel.getSize());
        button = new JButton("Test");
        JButton button2= new JButton("Button 2");
        panel.add(button);
        panel.add(button2);

        addComponentListener(new ComponentAdapter() {
            public void componentResized(ComponentEvent e) {
                System.out.println("here");
                System.out.println(panel.getSize());
                BgImageWidth = panel.getWidth();
                BgImageHeight = panel.getHeight();
                panel.repaint();
            }
        });
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        JPanelTest frame = new JPanelTest();
        frame.pack();
        frame.setSize(new Dimension(500, 500));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
        System.out.println(panel.getSize());
        System.out.println(panel.getPreferredSize());
    }

}

补充：软件开发 , Java ,