drawtest.java

Java程序设计实验与实训源代码经典的JAVA学习教材

//DrawTest.java

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

public class DrawTest
{  
   public static void main(String[] args)
   {  
      DrawFrame frame = new DrawFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.show();
   }
}

//一个包含图画面板的框架 
class DrawFrame extends JFrame
{
   public DrawFrame()
   {
      setTitle("DrawTest");
      setSize(WIDTH, HEIGHT);

      // 添加画板到框架

      DrawPanel panel = new DrawPanel();
      Container contentPane = getContentPane();
      contentPane.add(panel);
   }

   public static final int WIDTH = 400;
   public static final int HEIGHT = 400;  
}

//一个显示圆形、椭圆形、矩形的画板
 
class DrawPanel extends JPanel
{  
   public void paintComponent(Graphics g)
   {  
      super.paintComponent(g);
      Graphics2D g2 = (Graphics2D)g;

      // 绘制一个矩形

      double leftX = 100;
      double topY = 100;
      double width = 200;
      double height = 150;

      Rectangle2D rect = new Rectangle2D.Double(leftX, topY,
         width, height);
      g2.draw(rect);

      // 绘制一个椭圆形
      Ellipse2D ellipse = new Ellipse2D.Double();
      ellipse.setFrame(rect);
      g2.draw(ellipse);

      // 绘制一个斜线 

      g2.draw(new Line2D.Double(leftX, topY, 
         leftX + width, topY + height));

      // 绘制一在同一圆心的圆

      double centerX = rect.getCenterX();
      double centerY = rect.getCenterY();
      double radius = 150;

      Ellipse2D circle = new Ellipse2D.Double();
      circle.setFrameFromCenter(centerX, centerY,
         centerX + radius, centerY + radius);
      g2.draw(circle);
   }
}