bt.addKeyListener(new KeyAdapter() {
	@Override
	public void keyReleased(KeyEvent e) {
		if (e.getKeyCode() == KeyEvent.VK_ENTER) {
			System.exit(0);
		}
		if (e.getKeyCode() >= KeyEvent.VK_A && e.getKeyCode() <= KeyEvent.VK_Z) {
			System.out.println(e.getKeyCode());
		}
	}
});

//键盘监听,与鼠标监听一样也是在按钮等控件上的,
按钮实例调用addKeyListener
可以传入监听接口的实现类的子类对象..