求JAVA画布程序

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Img extends JFrame
{
Icon pic;
JButton buttonpre=new JButton("上一页");
JButton buttonnext=new JButton("下一页");
JLabel labelImg=new JLabel();
String path="E:/Img/pic.jpg";

public static void main(String args[])
{
Img frame1=new Img();
frame1.setTitle("JAVA画布程序");
frame1.setSize(660,460);
frame1.setVisible(true);
}

public Img()
{

getContentPane().setLayout(null);
buttonpre.addMouseListener(new MouseLis(1));
buttonnext.addMouseListener(new MouseLis(2));

pic=new ImageIcon(path);
labelexpImg.setIcon(pic);
getContentPane().add(labelexpImg);
getContentPane().add(buttonpre);
getContentPane().add(buttonnext);
labelexpImg.setBounds(30,70,400,300