您的问题可能是由于 JButton 在按下时窃取了焦点,导致您的 KeyListener 正在侦听未获得焦点的组件。再次,一个解决方案是使用键绑定。
我的sscce证明 KeyListeners 和 Key Bindings 在您尝试实现的转换后都可以正常工作:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.*;
import javax.swing.*;
@SuppressWarnings("serial")
public class TestUndecoratedKeyListener {
protected static final int PREF_W = 400;
protected static final int PREF_H = PREF_W;
private static void createAndShowGui() {
final JFrame frame = new JFrame("TestUndecoratedKeyListener");
final JPanel mainPanel = new JPanel() {
@Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
};
JToggleButton toggleButton = new JToggleButton("Full Screen");
toggleButton.setFocusable(false);
toggleButton.setMnemonic(KeyEvent.VK_F);
toggleButton.addItemListener(new ItemListener() {
@Override
public void itemStateChanged(ItemEvent e) {
if (e.getStateChange() == ItemEvent.SELECTED) {
frame.dispose();
frame.setUndecorated(true);
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setVisible(true);
} else {
frame.dispose();
frame.setUndecorated(false);
frame.setExtendedState(JFrame.NORMAL);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
});
mainPanel.add(toggleButton);
final JLabel keyListenerLabel = new JLabel();
final JLabel keyBindingLabel = new JLabel();
mainPanel.add(new JLabel("Press Right or Left Arrow Key To Test"));
mainPanel.add(keyListenerLabel);
mainPanel.add(keyBindingLabel);
keyListenerLabel.setBorder(BorderFactory.createLineBorder(Color.black));
keyBindingLabel.setBorder(BorderFactory.createLineBorder(Color.black));
mainPanel.addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
keyListenerLabel.setText("KeyListener: left pressed");
} else if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
keyListenerLabel.setText("KeyListener: right pressed");
}
}
});
int condition = JPanel.WHEN_IN_FOCUSED_WINDOW;
InputMap inputMap = mainPanel.getInputMap(condition);
ActionMap actionMap = mainPanel.getActionMap();
KeyStroke leftArrowStroke = KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0);
KeyStroke rightArrowStroke = KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0);
inputMap.put(leftArrowStroke, leftArrowStroke.toString());
inputMap.put(rightArrowStroke, rightArrowStroke.toString());
actionMap.put(leftArrowStroke.toString(), new AbstractAction() {
@Override
public void actionPerformed(ActionEvent arg0) {
keyBindingLabel.setText("Key Bindings: left Arrow Pressed");
}
});
actionMap.put(rightArrowStroke.toString(), new AbstractAction() {
@Override
public void actionPerformed(ActionEvent arg0) {
keyBindingLabel.setText("Key Bindings: right Arrow Pressed");
}
});
mainPanel.setFocusable(true);
mainPanel.requestFocusInWindow();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}