屏幕上任意位置的 Java 鼠标移动

Question

我确信这是可能的，但我所有的搜索都是空白的。

在 Java 中是否可以在 Java 应用程序之外注册鼠标移动事件？因此，如果鼠标指针在屏幕上的任何位置移动，我就会收到回电。通过轮询MouseInfo.getPointerInfo 可以得出近似值，但必须有更好的方法。

谢谢

解释用例： 这只是一个宠物项目，但基本上是在鼠标碰到屏幕边缘时触发事件。我还认为如果您尝试推过屏幕边缘，可能会触发不同的事件。为此，我认为鼠标运动监听器可能更合适。

Answer 1

java.awt.event.MouseMotionListener 只会为您提供有关鼠标在应用程序窗口内移动的信息。对于在该窗口之外发生的事件，没有办法绕过MouseInfo.getPointerInfo。但是，您可以编写一个（可能是单例）类，定期轮询指针信息并允许添加 MouseMotionListeners：

import java.awt.Component;
import java.awt.MouseInfo;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.util.HashSet;
import java.util.Set;

import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

/**
 * This class checks the position every #DELAY milliseconds and 
 * informs all registered MouseMotionListeners about position updates.
 */
public class MouseObserver {
    /* the resolution of the mouse motion */
    private static final int DELAY = 10;

    private Component component;
    private Timer timer;
    private Set<MouseMotionListener> mouseMotionListeners;

    protected MouseObserver(Component component) {
        if (component == null) {
            throw new IllegalArgumentException("Null component not allowed.");
        }

        this.component = component;

        /* poll mouse coordinates at the given rate */
        timer = new Timer(DELAY, new ActionListener() {
                private Point lastPoint = MouseInfo.getPointerInfo().getLocation();

                /* called every DELAY milliseconds to fetch the
                 * current mouse coordinates */
                public synchronized void actionPerformed(ActionEvent e) {
                    Point point = MouseInfo.getPointerInfo().getLocation();

                    if (!point.equals(lastPoint)) {
                        fireMouseMotionEvent(point);
                    }

                    lastPoint = point;
                }
            });
        mouseMotionListeners = new HashSet<MouseMotionListener>();
    }

    public Component getComponent() {
        return component;
    }

    public void start() {
        timer.start();
    }

    public void stop() {
        timer.stop();
    }

    public void addMouseMotionListener(MouseMotionListener listener) {
        synchronized (mouseMotionListeners) {
            mouseMotionListeners.add(listener);
        }
    }

    public void removeMouseMotionListener(MouseMotionListener listener) {
        synchronized (mouseMotionListeners) {
            mouseMotionListeners.remove(listener);
        }
    }

    protected void fireMouseMotionEvent(Point point) {
        synchronized (mouseMotionListeners) {
            for (final MouseMotionListener listener : mouseMotionListeners) {
                final MouseEvent event =
                    new MouseEvent(component, MouseEvent.MOUSE_MOVED, System.currentTimeMillis(),
                                   0, point.x, point.y, 0, false);

                SwingUtilities.invokeLater(new Runnable() {
                        public void run() {
                            listener.mouseMoved(event);
                        }
                    });
            }
        }
    }

    /* Testing the ovserver */
    public static void main(String[] args) {
        JFrame main = new JFrame("dummy...");
        main.setSize(100,100);
        main.setVisible(true);

        MouseObserver mo = new MouseObserver(main);
        mo.addMouseMotionListener(new MouseMotionListener() {
                public void mouseMoved(MouseEvent e) {
                    System.out.println("mouse moved: " + e.getPoint());
                }

                public void mouseDragged(MouseEvent e) {
                    System.out.println("mouse dragged: " + e.getPoint());
                }
            });

        mo.start();
    }
}

请注意，与您的标准 MouseMotionListener 存在一些显着差异：

• 您只会收到mouseMoved 事件，绝不会收到mouseDragged 事件。这是因为无法接收有关主窗口外点击的信息。
• 出于类似原因，每个MouseEvent 的modifiers 将始终为0。
• 同样适用于值clickCount、popupTrigger、button
• 您需要提供一个虚拟的java.awt.Component，用作MouseEvents 的（假）源 - 这里不允许使用null 值。