amazon 设计 13 drawboard

public class Drawboard extends JFrame{
       Graphics g;
       public static void main(String[] args){
              Drawboard d = new Drawboard();
              d.showUI();
       }
      
 
 
 public void showUI(){
       Graphics g ;
        this.setTitle("画图板");
        this.setSize(600,600);
        this.setDefaultCloseOperation(3);
        this.setResizable(false);
        
      
        java.awt.FlowLayout fl = new java.awt.FlowLayout();
        this.setLayout(fl);
        JPanel p = new JPanel();
        this.add(p);
     //      创建一个面板
        p.setPreferredSize(new Dimension(550,400));
     //   设置面板颜色
        p.setBackground(Color.green);
        JRadioButton jr1 =new JRadioButton("line");
        jr1.setActionCommand("直线");
        JRadioButton jr2 =new JRadioButton("rectangle");
        jr2.setActionCommand("矩形");
        JRadioButton jr3 =new JRadioButton("圆角矩形");
        jr3.setActionCommand("圆角矩形");
        JRadioButton jr4 =new JRadioButton("eclipse");
        jr4.setActionCommand("椭圆");
        JRadioButton jr5 =new JRadioButton("fill the rectangle");
        jr5.setActionCommand("填充矩形");
        JRadioButton jr6 =new JRadioButton("填充椭圆");
        jr6.setActionCommand("填充椭圆");
        JRadioButton jr7 =new JRadioButton("圆弧");
        jr7.setActionCommand("圆弧");
        //创建一个group（这是个容器）,并把所有单选对象放进去
        ButtonGroup group = new ButtonGroup();
        group.add(jr1);
        group.add(jr2);
        group.add(jr3);
        group.add(jr4);
        group.add(jr5);
        group.add(jr6);
        group.add(jr7);
 
        this.add(jr1);
        this.add(jr2);
        this.add(jr3);
        this.add(jr4);
        this.add(jr5);
        this.add(jr6);
        this.add(jr7);
        this.setVisible(true);
        //创建一个画布
        g = this.getGraphics();
       //创建鼠标监听器对象
        mouselistener lis = new mouselistener(g,group);
       this.addMouseListener(lis);
      }
}
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
 
import javax.swing.ButtonGroup;
public class mouselistener implements MouseListener {
       int x1,x2,y1,y2;
       private Graphics g;
       public String command;
       ButtonGroup group;
       public mouselistener(Graphics g,ButtonGroup group){
              this.g = g;
              this.group = group;
      
       }
       //鼠标按键在组件上按下时调用
       public void mousePressed(MouseEvent e){
              x1=e.getX();
              y1=e.getY();
       }
       //鼠标按钮在组件上释放时调用。
       public void mouseReleased(MouseEvent e){
              x2=e.getX();
              y2=e.getY();
              String command = group.getSelection().getActionCommand();
              if("直线".equals(command))
              //画直线
              g.drawLine(x1, y1, x2, y2);
              else if("矩形".equals(command))
              //绘制矩形
         g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1));
              else if("椭圆".equals(command))
         //绘制椭圆
         g.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1));
              else if("填充矩形".equals(command))
         //填充矩形
         g.fillRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1));
              else if("圆角矩形".equals(command))
        
         //圆角矩形
         g.drawRoundRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1),12,12);
              else if("填充椭圆".equals(command))
         //填充椭圆
         g.fillOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1));
              else if("圆弧".equals(command))
         //画圆弧
         g.drawArc(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1),45,90);
       }
       public void mouseClicked(MouseEvent e){}
       public void mouseEntered(MouseEvent e){}
       public void mouseExited(MouseEvent e){}
}