java中image显示图片，随上下左右键移动

import java.awt.*;
import java.awt.event.*;

class FTest {
  public static void main(String[] args){
     final MyFrame form = new MyFrame();
    // form.setBounds(100, 100, 500, 500);
     
     form.setMyFullScreen();
     form.addWindowListener(new Wclose());
     form.addKeyListener(new KeyAdapter(){
        public void keyPressed(KeyEvent e){
            
            form.w=form.getWidth();//获取当前窗口的大小
            form.h=form.getHeight();
            if(e.getKeyCode()==KeyEvent.VK_DOWN){
                if(form.p.y < form.h-form.imH){
                    form.repaint(form.p.x,form.p.y,form.imW, form.StepLength);
                    form.p.y=form.p.y+form.StepLength;
                    
                }
            }
            else if(e.getKeyCode()==KeyEvent.VK_UP){
                if(form.p.y>form.getX()){
                    form.repaint(form.p.x,form.p.y+form.imH-form.StepLength,form.imW, form.StepLength);
                    form.p.y-=form.StepLength;
                }
            }
            else if(e.getKeyCode()==KeyEvent.VK_LEFT){
                if(form.p.x>form.getY()){
                    form.repaint(form.p.x+form.imW-form.StepLength,form.p.y,form.StepLength, form.imH);
                    form.p.x-=form.StepLength;
                }
            }
            else if(e.getKeyCode()==KeyEvent.VK_RIGHT){
                if(form.p.x<form.w-form.imW){
                    form.repaint(form.p.x,form.p.y,form.StepLength, form.imH);
                    form.p.x+=form.StepLength;
                }
            }
            form.paint(form.getGraphics());//重绘，调用的是重写的paint
        }
    });
     form.setVisible(true);
  }
}

class MyFrame extends Frame {
  Image mImages;//定义了两张图片对象
  Image mImages2;
  int StepLength=10;
  int imH=100;//图像的大小
  int imW=100;
  int h=300;//当前的窗口的大小
  int w=400;
  Point p=new Point(20,20);//用来记录图像左上方定点的位置
 // Point pF=new Point(0,0);
  MyFrame(){
    setSize(h,w);
    
    mImages = getToolkit().getImage("ap1.jpg");//创建图片对象
    mImages2 = getToolkit().getImage("ap2.jpg");
    
    //java加载图象是异步的。也就是说，在你执行到getwidth时，它还不一定读完图象。所以当然是-1了。 
    //可以用下面的程序等待加载 
    MediaTracker   media   =   new   MediaTracker(this); 
    media.addImage(mImages2,1); 
    try{media.waitForID(1);}
    catch(InterruptedException e){
    }
    //如果没有上面这段程序，imH,和imW就会是-1
    imH=mImages2.getHeight(null);
    imW=mImages2.getWidth(null);
  }
  public void paint(Graphics g){
    g.drawImage(mImages2,p.x,p.y,imW,imH,this);
  }
  
  public void setMyFullScreen(){
      //把当前frame设置成全屏
      Dimension   screenSize=this.getToolkit().getScreenSize(); 
      this.setSize(screenSize.width,screenSize.height); 
      this.setUndecorated(true); 
      this.setExtendedState(Frame.MAXIMIZED_BOTH);
  }
}

class Wclose extends WindowAdapter {
    public void windowClosing(WindowEvent e) {
    System.exit(0);
    }
}