java 2D图形绘制

package jisuan;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import javax.swing.JComponent;
import javax.swing.JFrame;
public class Drawtest {
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new DrawFrame();
                frame.setTitle("计算器");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setVisible(true);
            }
        });
    }
}
class DrawFrame extends JFrame
{
    /**
     * 创建一个窗口
     */
    private static final long serialVersionUID = 1L;
    public DrawFrame() {
        add(new DrawComponent());
        pack();
    }
}
class DrawComponent extends JComponent
{
    /**
     * 画图
     */
    private static final long serialVersionUID = 1L;
    private static final int DEFAULT_WIDTH = 400;
    private static final int DEFAULY_HEIQHT = 400;
    public void paintComponent(Graphics g) {
        Graphics2D g2 = (Graphics2D)g;
        double leftX = 100;
        double topY = 100;
        double width = 200;
        double height = 150;
        //长方形
        Rectangle2D rect = new Rectangle2D.Double(leftX, topY , width , height);
        g2.draw(rect);
        //椭圆
        Ellipse2D ellipse = new Ellipse2D.Double();
        ellipse.setFrame(rect);
        g2.draw(ellipse);
        //画斜线
        g2.draw(new Line2D.Double(leftX ,topY ,leftX + width, topY + height));
        //大园
        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);
    }
    public Dimension getPreferredSize() {
        return new Dimension(DEFAULT_WIDTH, DEFAULY_HEIQHT);
    }
}