java的键盘事件

最近看到有人问怎么模拟钢琴操作

想了想怎么实现 顺便看了下键盘事件

可以用两种方式

1、

public class KeystrokeTest extends JApplet {
private JButton button = new JButton("button");
public void init() {
　 Container contentPane = getContentPane();
　 JPanel panel = new JPanel();
　 JCheckBox checkbox = new JCheckBox("checkbox");
　 JButton southButton = new JButton("south button");
　 Listener listener = new Listener();
　 panel.setBorder(BorderFactory
　　 .createTitledBorder(("Ancestor of button and checkbox")));
　 checkbox.registerKeyboardAction(listener, KeyStroke.getKeyStroke (
　　 KeyEvent.VK_F, 0, false), JComponent.WHEN_FOCUSED);
　 panel.registerKeyboardAction(listener, KeyStroke.getKeyStroke (
　　 KeyEvent.VK_A, InputEvent.ALT_MASK, false),
　　 JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
　 southButton.registerKeyboardAction(listener, KeyStroke.getKeyStroke(
　　 KeyEvent.VK_W, 0, true), JComponent.WHEN_IN_FOCUSED_WINDOW);
　 panel.add(button);
　 panel.add(checkbox);
　 contentPane.add(panel, "Center");
　 contentPane.add(southButton, "South");
}
}
class Listener implements ActionListener {
public void actionPerformed(ActionEvent e) {
　 Object src = e.getSource();
　 String cname = src.getClass().getName();
　 if (src instanceof JCheckBox) {
　 System.out.print("'f' key PRESSED when checkbox");
　 System.out.println(" had focus");
　 } else if (src instanceof JPanel) {
　 System.out.print("'ALT-a' key PRESSED when ancestor");
　 System.out.println(" of titled panel had focus");
　 } else if (src instanceof JButton) {
　 System.out.print("'w' key RELEASED when any");
　 System.out.println(" component in window had focus");
　 }
　 System.out.println("Source: " + cname);
　 System.out.println();
}
}