怎么加入启动封面？

import java.awt.*;
import java.awt.event.*;public class splashTest extends Frame
{
Toolkit toolkits=Toolkit.getDefaultToolkit();
Window Windows;
Image Images;

public static void main(String args[])
{
Frame frame=new splashTest();
}

public splashTest()
{
ImageCanvas Canvas1;
Windows =new Window(this);
Images  =toolkits.getImage("saint.jpg");
Canvas1 =new ImageCanvas(Images);

Windows.add(Canvas1,"Center");

Dimension scrnSize  =toolkits.getScreenSize();
int       imgWidth =Images.getWidth(this),
  imgHeight=Images.getHeight(this);

Windows.setLocation(scrnSize.width/2-(imgWidth/2),
        scrnSize.height/2-(imgHeight/2));
Windows.setSize(imgWidth,imgHeight);
Windows.show();
Windows.toFront();        

try  {Thread.currentThread().sleep(20000);}
catch(Exception e) {e.printStackTrace();}

Windows.dispose();
System.exit(0);
}
}
class ImageCanvas extends Canvas
{
private Image Images;

public ImageCanvas(Image Images)
{
MediaTracker mt=new MediaTracker(this);
mt.addImage(Images,0);

try {mt.waitForID(0);}
catch(Exception e) { e.printStackTrace();}

this.Images=Images;
}

public void paint(Graphics g)
{
g.drawImage(Images,0,0,this);
}

public void update(Graphics g)
{
paint(g);
}
public Dimension getPreferredSize()
{
return new Dimension(Images.getWidth(this),Images.getHeight(this));
}
}
你自己找一个图片命名saint.jpg