java阿基米德螺线

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

public class SpiralJFrame extends JFrame implements ActionListener {
 
 private SpiralCanvas canvas;
 
 public SpiralJFrame()
 {
  super("阿基米德螺线");
  Dimension dim=getToolkit().getScreenSize();
  this.setBounds(dim.width/4,dim.height/4,dim.width/2,dim.height/2);
  this.setDefaultCloseOperation(EXIT_ON_CLOSE);
  JPanel jpanel=new JPanel();
  this.getContentPane().add(jpanel, "North");
  JButton button_color=new JButton("颜色选择");
  jpanel.add(button_color);
  button_color.addActionListener(this);
  this.canvas=new SpiralCanvas(Color.red);
  this.getContentPane().add(this.canvas, "Center");
  this.setVisible(true);
 }
 
 
 
 @Override
 public void actionPerformed(ActionEvent arg0) {
  Color c=JColorChooser.showDialog(this, "选择颜色", Color.blue);
  this.canvas.setColor(c);
  this.canvas.repaint();
 }
 public static void main(String arg[]){
  new SpiralJFrame();
 }

}

class SpiralCanvas extends Canvas {
 
 private Color color;
 public SpiralCanvas(Color color){
  this.setColor(color);
 }
 public void setColor(Color color){
  this.color=color;
 }
 public void paint(Graphics g){
  
  int x0=this.getWidth()/2;
  int y0=this.getHeight()/2;
  g.setColor(this.color);
  g.drawLine(x0, 0, x0, y0*2);
  g.drawLine(0, y0, x0*2, y0);
  
  double r;
  for(int i=0;i<2000;i++){
   r=0.1*i;
   int x =(int) ( r * Math.cos(5*r*Math.PI/180));
      int y = (int) (r * Math.sin(5*r*Math.PI/180));
   g.fillOval(x0+x, y0+y, 2, 2);
  }
  
 }
 
}