java 键盘事件_java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();

}

}

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的源代码发现registerKeyboardAction方法其实就是把

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();

}

});封装了一下

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);

}

}

}

不过api中提到

registerKeyboardAction方法现在已过时，对于类似的操作，请结合使用 getActionMap() 和 getInputMap()，即第二种方法为java推荐的方法

好像在哪看到过java中不提倡使用addKeyListener();

知道的可以说以下