Java程序开发中如何实现，移动的小图片，不移出窗体，到窗体边框的时候自动改变方向？

import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;

import javax.swing.JFrame;
public class test extends JFrame{
private int xx, yy;
private boolean isDraging = false;
public test(){
setUndecorated(true); // 没有标题栏
setSize(200, 200);
setVisible(true);
this.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
isDraging = true;
xx = e.getX();
yy = e.getY();
}

public void mouseReleased(MouseEvent e) {
isDraging = false;
}
});
this.addMouseMotionListener(new MouseMotionAdapter() {
public void mouseDragged(MouseEvent e) {
if (isDraging) {
int left = getLocation().x;
int top = getLocation().y;
setLocation(left + e.getX() - xx, top + e.getY() - yy);
}
}
});
}
public static void main(String[] args) {
test t =new test();
t.setDefaultCloseOperation(3);
}
}

试试用线程