Swing(和大多数GUI)是事件驱动的环境.也就是说,某些事情发生了,您对此做出了反应.

让循环等待某种动作是一种反直观(IMHO).

一般来说,如果可以,应该避免使用KeyListeners.他们有重点关注的问题. key bindings API具有克服此限制的方法.

它允许您针对Action注册一个KeyStroke,并允许您的程序坐下来等到发生某种事情为止.

import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.Dimension;

import java.awt.EventQueue;

import java.awt.Graphics;

import java.awt.Graphics2D;

import java.awt.GridBagConstraints;

import java.awt.GridBagLayout;

import java.awt.event.ActionEvent;

import java.awt.event.KeyEvent;

import javax.swing.AbstractAction;

import javax.swing.ActionMap;

import javax.swing.InputMap;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.KeyStroke;

import javax.swing.UIManager;

import javax.swing.UnsupportedLookAndFeelException;

import javax.swing.border.LineBorder;

public class KeyBindings {

public static void main(String[] args) {

new KeyBindings();

}

public KeyBindings() {

EventQueue.invokeLater(new Runnable() {

@Override

public void run() {

try {

UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {

}

JFrame frame = new JFrame("Testing");

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

frame.setLayout(new BorderLayout());

frame.add(new TestPane());

frame.pack();

frame.setLocationRelativeTo(null);

frame.setVisible(true);

}

});

}

public class TestPane extends JPanel {

public TestPane() {

setLayout(new GridBagLayout());

GridBagConstraints gbc = new GridBagConstraints();

gbc.gridx = 1;

gbc.gridy = 0;

add(new KeyPane(KeyEvent.VK_UP, 0), gbc);

gbc.gridy = 2;

add(new KeyPane(KeyEvent.VK_DOWN, 0), gbc);

gbc.gridx = 0;

gbc.gridy = 1;

add(new KeyPane(KeyEvent.VK_LEFT, 0), gbc);

gbc.gridx = 2;

add(new KeyPane(KeyEvent.VK_RIGHT, 0), gbc);

}

}

public class KeyPane extends JPanel {

public KeyPane(int keyCode, int modifier) {

setBorder(new LineBorder(Color.DARK_GRAY));

InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);

ActionMap am = getActionMap();

im.put(KeyStroke.getKeyStroke(keyCode, modifier, false), "keyPressed");

im.put(KeyStroke.getKeyStroke(keyCode, modifier, true), "keyReleased");

am.put("keyPressed", new AbstractAction() {

@Override

public void actionPerformed(ActionEvent e) {

setBackground(Color.RED);

}

});

am.put("keyReleased", new AbstractAction() {

@Override

public void actionPerformed(ActionEvent e) {

setBackground(UIManager.getColor("Panel.background"));

}

});

}

@Override

public Dimension getPreferredSize() {

return new Dimension(20, 20);

}

}

}