java - KeyListener - 调用了 keyPressed 但未调用 KeyReleased

Question

无需发布太多代码，简而言之，我有一个表现有趣的 KeyListener

我有一个 JPanel，我这样实现我的 KeyListener:

keyboard = new KeyBoard(); // implements KeyListener
KeyboardFocusManager manager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
manager.addKeyEventDispatcher(new DefaultKeyEventDispatcher(keyboard));

我之前也试过这样的:

theJPanel.addKeyListener(myKeyListener);
theJPanel.setFocusable(true);
theJPanel.requestFocusInWindow();

主要问题:

当问题发生时，public void keyPressed(KeyEvent e) 总是被调用，但是public void keyReleased(KeyEvent e) 从不被调用。

当它发生时似乎无法预测，因为其他时候一切正常。如果我等待大约 5 分钟并重新运行程序，这个错误就会消失 :/

编辑:(忘记发布 DefaultKeyEventDispatcher 代码)

package game.keyboard;

import java.awt.KeyEventDispatcher;
import java.awt.event.KeyEvent;

public class DefaultKeyEventDispatcher implements KeyEventDispatcher {

    private KeyBoard keyboard;

    public DefaultKeyEventDispatcher(KeyBoard keyboard) {
        this.keyboard = keyboard;
    }

    @Override
    public boolean dispatchKeyEvent(KeyEvent e) {
        if (e.getID() == KeyEvent.KEY_PRESSED) {
            keyboard.keyPressed(e);
        } else if (e.getID() == KeyEvent.KEY_RELEASED) {
            keyboard.keyReleased(e);
        } else if (e.getID() == KeyEvent.KEY_TYPED) {
            keyboard.keyTyped(e);
        }
        return false;
    }
}

编辑 2. KeyBoard 类中的示例

package game.keyboard;

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

public class KeyBoard implements KeyListener {

    private boolean[] keys;

    private long[] keyPressedTime;

    public KeyBoard() {
        keys = new boolean[KeyEvent.KEY_LAST];
        keyPressedTime = new long[KeyEvent.KEY_LAST];
    }

    @Override
    public void keyTyped(KeyEvent e) {
    }

    @Override
    public void keyPressed(KeyEvent e) {
        keys[e.getKeyCode()] = true;
        keyPressedTime[e.getKeyCode()] = System.currentTimeMillis();
    }

    @Override
    public void keyReleased(KeyEvent e) {
        keys[e.getKeyCode()] = false;   
        keyPressedTime[e.getKeyCode()] = -1;
    }

    public long keyPressedTime(int k) {
        return keyPressedTime[k];
    }

    public boolean isKeyPressed(int k) {
        return keys[k];
    }

    public boolean isKeyCombo(int[] k) {
        boolean ret = true;
        for(int i = 0;i < k.length; i++) {
            ret &= keys[k[i]];
        }
        return ret;
    }

}

Answer 1

这...

keyboard = new KeyBoard(); // implements KeyListener
KeyboardFocusManager manager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
manager.addKeyEventDispatcher(new DefaultKeyEventDispatcher(keyboard));

不是注册KeyListener的方法。这将允许您查看应用程序处理的所有 key 。 KeyEventDispatcher 没有 keyPressed 或 keyReleased 方法，只有 dispatchKeyEvent。

JDK 中没有 DefaultKeyEventDispatcher 这样的类，所以你必须使用自定义版本，这意味着，我们不知道问题到底是什么，因为我们无法复制它或研究一下。

如果不知道您要达到的目标是什么，就不可能提供准确的指导，但您可能希望从 How to Write a Key Listener 开始