java - 如何检查用户是否按下了某个键？

Question

在java中，我有一个程序需要连续检查用户是否按下了某个键。所以在伪代码中，类似

if (isPressing("w")) {
   // do somthing
}

Answer 1

在java中，你不会检查是否按下了某个键，而是听 KeyEvent s。实现您目标的正确方法是注册 KeyEventDispatcher ，并实现它来维护所需 key 的状态:

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

public class IsKeyPressed {
    private static volatile boolean wPressed = false;
    public static boolean isWPressed() {
        synchronized (IsKeyPressed.class) {
            return wPressed;
        }
    }

    public static void main(String[] args) {
        KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(new KeyEventDispatcher() {

            @Override
            public boolean dispatchKeyEvent(KeyEvent ke) {
                synchronized (IsKeyPressed.class) {
                    switch (ke.getID()) {
                    case KeyEvent.KEY_PRESSED:
                        if (ke.getKeyCode() == KeyEvent.VK_W) {
                            wPressed = true;
                        }
                        break;

                    case KeyEvent.KEY_RELEASED:
                        if (ke.getKeyCode() == KeyEvent.VK_W) {
                            wPressed = false;
                        }
                        break;
                    }
                    return false;
                }
            }
        });
    }
}

然后您可以随时使用:

if (IsKeyPressed.isWPressed()) {
    // do your thing.
}

当然，你可以使用同样的方法来实现 isPressing("<some key>")包含键及其状态的映射 IsKeyPressed .