编写java一个程序，点击第一幅、上一幅、下一幅、最后一幅按钮，可浏览加载的五幅图片，实现简单图片浏览

import java.awt.CardLayout;
import java.awt.event.*;

import javax.swing.*;

public class ChangePic extends JFrame implements ActionListener {
private static final long serialVersionUID = 1L;
public JButton btnFir, btnLast, btnBef, btnNext;
CardLayout card = new CardLayout();
public JPanel p, pTop, p1, p2, p3, p4;
public JLabel lb1, lb2, lb3, lb4;
String imgpath[] = { "D:/图片/hx/01[1].gif", "D:/图片/hx/02[1].gif",
"D:/图片/hx/03[1].gif", "D:/图片/hx/04[1].gif" };

public ChangePic() {
initCom();
}

public void initCom() {
btnFir = new JButton("第一张");
btnLast = new JButton("最后一张");
btnBef = new JButton("上一张");
btnNext = new JButton("下一张");
btnFir.addActionListener(this);
btnLast.addActionListener(this);
btnBef.addActionListener(this);
btnNext.addActionLis