eclipse awt包在图片上显示文字

package awt;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.*;
import java.awt.geom.Rectangle2D;
import java.util.Date;
import javax.swing.*;
public class DrawString extends JFrame {
  //三个对象 在图片上显示问题
  private Shape rect;
  private Font font;
  private Date date;
  public DrawString() {
    rect=new Rectangle2D.Double(10,10,200,80);
    font=new Font("宋体",Font.BOLD,16);
    date=new Date();
    //设置窗体大小 关闭模式 标题 面板等等
    this.setSize(230,140);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      add(new CanvasPanel());
      this.setTitle("绘图文本");
  }
  public static void main(String[]args) {
    new DrawString().setVisible(true);
  } 
  class CanvasPanel extends Canvas{
    public void paint(Graphics g) {
      super.paint(g);
      //绘制加填充
      Graphics2D g2=(Graphics2D)g;
      g2.setColor(Color.green);
      g2.fill(rect);
      g2.setColor(Color.blue);
      g2.setFont(font);
      g2.drawString("现在时间是",20,30);
      g2.drawString(String.format("%tr",date), 50, 60);
    }
  }
}