Java KeyBindings 组合不起作用

Question

我正在努力创建一种识别组合键的方法。在我设置任何 boolean 值之前，我注意到某些组合键会导致忽略其他键。

package question;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;

import javax.swing.AbstractAction;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;

public class Example extends JPanel {

/**
 * 
 */
private static final long serialVersionUID = 1L;

public Example() {

    setBackground(Color.DARK_GRAY);
    setPreferredSize(new Dimension(500,500));
    setFocusable(true);
    requestFocusInWindow();

    getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0), "action_a");
    getActionMap().put("action_a", new AbstractAction() {

        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println("A has been pressed!");
        }
    });
    getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0), "action_s");
    getActionMap().put("action_s", new AbstractAction() {

        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println("S has been pressed!");
        }
    });
    getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0), "action_d");
    getActionMap().put("action_d", new AbstractAction() {

        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println("D has been pressed!"); // This code is reached, even when you are holding down the A key and S key 
        }
    });getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_J, 0), "action_j");
    getActionMap().put("action_j", new AbstractAction() {

        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println("J has been pressed!");
        }
    });
    getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_K, 0), "action_k");
    getActionMap().put("action_k", new AbstractAction() {

        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println("K has been pressed!");
        }
    });
    getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_L, 0), "action_l");
    getActionMap().put("action_l", new AbstractAction() {

        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println("L has been pressed!"); // This code is never reached when you hold down the J key and K key
        }
    });

    JFrame frame;       
    frame = new JFrame("KeyBinding problem");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(this, BorderLayout.CENTER);
    frame.pack();       
    frame.setResizable(false);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
}

public static void main(String[] args) {
    Example example = new Example();
}
}

我现在已按照推荐使用 KeyBindings 以启用组合键。但是，我面临的问题是，当某些键被同时按下时，并非所有键都被注册。使用我的示例，尝试以下场景:

启动示例并按住 A 键。控制台会不断打印出“A has been pressed!”。现在，在按住 A 键的同时，另外添加 S 键并按住它。控制台现在将停止打印“A has been pressed!”并打印出“S已被按下!”不断地，而不是。现在按住 A 键、S 键和 D 键。这将导致控制台不断打印出“D has been pressed!”。

现在，重新启动一切，但不要使用 A、S 和 D 键，而是使用 J、K 和 L 键。 这仅适用于 J 和 K，L 键将被忽略。

-> 顺便说一下，我正在使用 Windows 8.1(64 位)。使用 Aspire E1-772G 笔记本电脑。

谁能告诉我为什么会这样，我该如何解决甚至解决这个问题？提前致谢!

干杯。

*编辑我添加了另一个示例，它也直观地显示了问题。我不可能让所有标签立即变红。 J+K+L 的组合对我来说似乎有问题。 这与一次按下的键数无关，因为它在我的主程序中也适用于 6 个键。它只是 J+K 的组合，似乎停止触发 L 键的 KeyEvents。这似乎也发生在 KeyListeners 中，如下例所示。

package question;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.BitSet;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class Example extends JPanel implements KeyListener, Runnable {

/**
 * 
 */
private static final long serialVersionUID = 1L;
private BitSet bitSet;
private Thread thread;
private JLabel a_key, s_key, d_key, j_key, k_key, l_key;

public Example() {      
    setBackground(Color.DARK_GRAY);
    setPreferredSize(new Dimension(700,300));
    addKeyListener(this);
    setFocusable(true);
    requestFocusInWindow();

    bitSet = new BitSet(256);
    thread = new Thread(this);

    a_key = new JLabel("A");
    a_key.setBackground(Color.YELLOW);
    a_key.setPreferredSize(new Dimension(50,50));
    a_key.setOpaque(true);

    s_key = new JLabel("S");
    s_key.setBackground(Color.YELLOW);
    s_key.setPreferredSize(new Dimension(50,50));
    s_key.setOpaque(true);

    d_key = new JLabel("D");
    d_key.setBackground(Color.YELLOW);
    d_key.setPreferredSize(new Dimension(50,50));
    d_key.setOpaque(true);

    j_key = new JLabel("J");
    j_key.setBackground(Color.YELLOW);
    j_key.setPreferredSize(new Dimension(50,50));
    j_key.setOpaque(true);

    k_key = new JLabel("K");
    k_key.setBackground(Color.YELLOW);
    k_key.setPreferredSize(new Dimension(50,50));
    k_key.setOpaque(true);

    l_key   = new JLabel("L");
    l_key.setBackground(Color.YELLOW);
    l_key.setPreferredSize(new Dimension(50,50));
    l_key.setOpaque(true);

    add(a_key);
    add(s_key);
    add(d_key);
    add(j_key);
    add(k_key);
    add(l_key);

    JFrame frame;       
    frame = new JFrame("Key Event problem");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.add(this, BorderLayout.CENTER);
    frame.pack();       
    frame.setResizable(false);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);

    thread.start();
}

public static void main(String[] args) {
    Example example = new Example();
}

@Override
public void keyPressed(KeyEvent e) {
    int keyCode = e.getKeyCode();
    if(bitSet.get(keyCode) == false) {
        bitSet.set(keyCode);
    }       
}

@Override
public void keyReleased(KeyEvent e) {
    int keyCode = e.getKeyCode();
    bitSet.clear(keyCode);
}

@Override
public void keyTyped(KeyEvent e) {

}

private boolean isKeyPressed(int keyCode) {
    return bitSet.get(keyCode);
}

@Override
public void run() {
    while(true) {
        if(isKeyPressed(KeyEvent.VK_A)) {
            a_key.setBackground(Color.red);
        }
        else {
            if(a_key.getBackground() == Color.red) {
                a_key.setBackground(Color.yellow);
            }               
        }
        if(isKeyPressed(KeyEvent.VK_S)) {
            s_key.setBackground(Color.red);
        }
        else {
            if(s_key.getBackground() == Color.red) {
                s_key.setBackground(Color.yellow);
            }               
        }
        if(isKeyPressed(KeyEvent.VK_D)) {
            d_key.setBackground(Color.red);
        }
        else {
            if(d_key.getBackground() == Color.red) {
                d_key.setBackground(Color.yellow);
            }               
        }
        if(isKeyPressed(KeyEvent.VK_J)) {
            j_key.setBackground(Color.red);
        }
        else {
            if(j_key.getBackground() == Color.red) {
                j_key.setBackground(Color.yellow);
            }               
        }
        if(isKeyPressed(KeyEvent.VK_K)) {
            k_key.setBackground(Color.red);
        }
        else {
            if(k_key.getBackground() == Color.red) {
                k_key.setBackground(Color.yellow);
            }               
        }
        if(isKeyPressed(KeyEvent.VK_L)) {
            l_key.setBackground(Color.red);
        }
        else {
            if(l_key.getBackground() == Color.red) {
                l_key.setBackground(Color.yellow);
            }               
        }
    }
}
}

Answer 1

可能这与 key 翻转有关:https://en.wikipedia.org/wiki/Rollover_(key)有些键盘与 WASD 键有特殊连接，因为它们在游戏中经常使用。