frame = new JFrame();//��ʼ�����漰�˵�
frame.getContentPane().add(new Screen());
frame.addKeyListener(this);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container contentPane = frame.getContentPane();
contentPane.addMouseListener(this);
contentPane.addMouseMotionListener(this);
menuBar = new JMenuBar();
gameMenu = new JMenu("��Ϸ");
helpMenu =new JMenu("����");