1.主类
package s1221画图板重绘撤销;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.util.ArrayList;
import javax.swing.*;

public class Main1221 extends JFrame{
	ImageIcon image[]={
		    new ImageIcon("E:/Michael/javaImage/扫雷图片/2.jpg"),//曲线
		    new ImageIcon("E:/Michael/javaImage/扫雷图片/2.jpg"),//直线
		    new ImageIcon("E:/Michael/javaImage/扫雷图片/2.jpg"), //矩形
		    new ImageIcon("E:/Michael/javaImage/扫雷图片/2.jpg"),//椭圆
		    };
	
	 String st[]={"曲线","直线","矩形","椭圆","橡皮","颜色笔","填色","放大镜","刷子","圆角矩形","涂鸦","文字","多边形","填充矩形","文字","多边形","填充矩形"};
	    	
	 Color b[] ={ Color.blue,Color.green,Color.lightGray,Color.orange,Color.black,
				Color.cyan,Color.darkGray,Color.gray,Color.magenta,Color.pink,Color.red,
				Color.yellow,Color.white,new Color(0,100,200),new Color(0,200,200)};
	    	static ArrayList<Shape> list = new ArrayList<Shape>();
	
	    	 Mymouselisten l1=new Mymouselisten();    //创建监听对象
	    	 
	public  Main1221()
	{   	
		   //设置窗体属性*********************************************
			this.setDefaultCloseOperation(3);//设置关闭的方式
			this.setLayout( new BorderLayout());//设置窗体为边框布局
			this.setSize(800, 600);//设置窗体的大小
			this.setTitle("画板");  //设置窗体的标题	
			this.setResizable(true);//设置窗体不可改变大小
			this.setLocationRelativeTo(null);//设置窗体出现在屏幕中间
			//设置窗体属性*********************************************

			//创建按钮**************************************

			JMenuBar jbar=new JMenuBar();
			JMenuItem t1=new JMenuItem("撤销");
		   	JMenu m1=new JMenu("选项");
		
		   	t1.addActionListener(l1);
		   	m1.add(t1);		
		   	jbar.add(m1);
	       	this.setJMenuBar(jbar);
	       	//创建按钮***************************************
	    
	        //左边的面板************************************
			JPanel west=new JPanel();
			west.setPreferredSize(new Dimension(80,0));
			west.setBackground(Color.lightGray);
			this.add(west,BorderLayout.WEST);
			//左边的面板************************************
	        
			//下方的面板********************************************
			JPanel south =new JPanel();
			south.setPreferredSize(new Dimension(0,100));
			south.setBackground(Color.pink);
			this.add(south,BorderLayout.SOUTH);
			//下方的面板*********************************************
			
			
			//绘画的面板**************************************************************
			 JPanel drawpanel =new JPanel()
			  {
						public void paint(Graphics g)         //重写JPanel中的方法
						{
							super.paint(g);								
							list.forEach((shape)->shape.draw(g));  //lambda表达式			
						}	
			 };
			//绘画的面板**************************************************************
		
			 
			 //中间的面板********************************************
			JPanel center =new JPanel();
			center.setBackground(Color.GRAY);
			center.setLayout(new BorderLayout());
			center.add(drawpanel);
			this.add(center,BorderLayout.CENTER);
			//中间的面板*********************************************
			
			drawpanel.setBackground(Color.WHITE);		
		    drawpanel.addMouseListener(l1);	             //给监听方法传递监听的对象 
		    drawpanel.addMouseMotionListener(l1);        //虽然l1实现了多个接口，但是面板要监听鼠标拖动事件，要分别添加方法
		    
		    
			//**********************************窗体左边的选项栏***************************************//
			for(int i=0;i<image.length;i++)
			{
			JButton jb=new JButton(image[i]);
			jb.setActionCommand(st[i]);                      //给这个图标添加action command 方便在事件中获取
			jb.setPreferredSize(new Dimension(image[i].getIconWidth(),image[i].getIconHeight()));
			jb.setToolTipText(st[i]);
			jb.addActionListener(l1); 
			west.add(jb);
			}			  
			//*****************************************************************************************//
			
			//**********************************窗体下方颜色选择框***************************************//	
			for(Color i:b)
			{
			 JButton jb1=new JButton("");	
			 jb1.setBackground(i);
			 jb1.setPreferredSize(new Dimension(30,30));
			 jb1.addActionListener(l1); 
			 south.add(jb1);
			}
			//*****************************************************************************************//
			
			this.setVisible(true);                           //要先设置窗体可见，然后再传画笔	
			Graphics g=drawpanel.getGraphics(); 			 //传递画笔 ，我一开始放在最后，结果不能显示！！！传画笔之前一定要先设置可见
			l1.setGraphics(g,list,drawpanel);		    
	}
	
	public static void main(String[] args) 
	{ Main1221 k=new Main1221();}
}