一个让label在背景图片上移动的程序，不知道为什么不能接受键盘的消息
import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.*;import java.awt.*;import java.awt.event.*;public class KeyMoveBackground extends JFrame{ private JLabel label; public KeyMoveBackground(){ super(); this.setResizable(false); this.setVisible(true); Container c = this.getContentPane(); this.setTitle("方向键移动背景"); this.setBounds(100,100,500,375); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); label = new JLabel(); ImageIcon icon = new ImageIcon(getClass().getResource("Penguins.jpg")); ImageIcon glassImg = new ImageIcon(getClass().getResource("QQ截图20120303162426.png")); label.setIcon(icon); label.setSize(icon.getIconWidth(),icon.getIconHeight()); label.setLocation(-icon.getIconWidth()/3,-icon.getIconHeight()/3); c.add(label); JLabel glassLabel = new JLabel(glassImg); JPanel glassPane = new JPanel(new BorderLayout()); glassPane.add(glassLabel); glassPane.setOpaque(false); this.setGlassPane(glassPane); this.getGlassPane().setVisible(true); this.addKeyListener(new KeyAdapter(){ public void keyPressed(KeyEvent e){ do_label_keyPress(e); } }); } protected void do_label_keyPress(final KeyEvent e){ int code = e.getKeyCode(); Point location = label.getLocation(); int step=3; switch(code){ case KeyEvent.VK_RIGHT: if(location.x > (getWidth() - label.getWidth())) label.setLocation(location.x-step,location.y); break; case KeyEvent.VK_LEFT: if(location.x<0) label.setLocation(location.x+step,location.y); break; case KeyEvent.VK_UP: if(location.y < 0) label.setLocation(location.x,location.y+step); break; case KeyEvent.VK_DOWN: if(location.y > (getHeight()-label.getHeight())) label.setLocation(location.x, location.y+step); break; default: break; } } public static void main(String[] args) { // TODO Auto-generated method stub new KeyMoveBackground(); }}