java的鍵盤事件

最近看到有人問怎麼模擬鋼琴操作

想了想怎麼實現 順便看了下鍵盤事件

可以用兩種方式

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();
}
}


2、

public class T {
public static void main(String[] args) {
　 try {
　 UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName ());
　 } catch (Exception e) {
　 }
　 final JTextField tf = new JTextField();
　 tf.setEnabled(false);
　 JPanel p = new JPanel(new GridLayout(0, 3, 5, 5));
　 for (int i = 0; i <= 9; i++) {
　 final JButton btn = new JButton(String.valueOf(i));
　 p.add(btn);
　 btn.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(
　　 KeyStroke.getKeyStroke((char) (i + '0')), "PressKeyAction");
　 btn.getActionMap().put("PressKeyAction", new AbstractAction() {
　　 public void actionPerformed(ActionEvent e) {
　　 btn.doClick();
　　 }
　 });
　 btn.addActionListener(new ActionListener() {
　　 public void actionPerformed(ActionEvent e) {
　　 tf.setText(tf.getText() + btn.getText());
　　 }
　 });
　 }
　 JFrame f = new JFrame();
　 JComponent contentPane = (JComponent) f.getContentPane();
　 contentPane.setLayout(new BorderLayout(0, 5));
　 contentPane.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
　 f.getContentPane().add(p, BorderLayout.CENTER);
　 f.getContentPane().add(tf, BorderLayout.NORTH);
　 f.pack();
　 f.setLocationRelativeTo(null);
　 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
　 f.setVisible(true);
}
}

看了下java的源代碼發現registerKeyboardAction方法其實就是把

btn.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(
　　 KeyStroke.getKeyStroke((char) (i + '0')), "PressKeyAction");
　 btn.getActionMap().put("PressKeyAction", new AbstractAction() {
　　 public void actionPerformed(ActionEvent e) {
　　 btn.doClick();
　　 }
　 });

封裝了一下

public void registerKeyboardAction(ActionListener anAction,String aCommand,KeyStroke aKeyStroke,int aCondition) {
InputMap inputMap = getInputMap(aCondition, true);
if (inputMap != null) {
　　 ActionMap actionMap = getActionMap(true);
　　 ActionStandin action = new ActionStandin(anAction, aCommand);
　　 inputMap.put(aKeyStroke, action);
　　 if (actionMap != null) {
　 actionMap.put(action, action);
　　 }
}
　　 }

不過api中提到

registerKeyboardAction方法現在已過時，對於類似的操作，請結合使用 getActionMap() 和 getInputMap()，即第二種方法為java推薦的方法

好像在哪看到過java中不提倡使用addKeyListener();

知道的可以說以下