Java JPanel_Bg設置背景

、

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());
	}

}