java如何获取JPanel中鼠标指针的位置（无需任何鼠标操作）？

Question

我可以通过在JPanel上添加一个MouseAdapter来获取鼠标指针的位置。但是，它只在用户移动鼠标指针或执行其他操作时起作用。代码如下：

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

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


public class LocationTest {
    public static void main(String[] args) {
        LocationTest locationTest = new LocationTest();
        locationTest.createUI();
    }

    public void createUI(){
        JFrame frame = new JFrame("Location Test");
        frame.setResizable(false);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        MainPanel mainPanel = new MainPanel();
        mainPanel.addMouseListener(new CustomMouseListener());
        mainPanel.addMouseMotionListener(new CustomMouseListener());
        frame.add(mainPanel,BorderLayout.CENTER);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    @SuppressWarnings("serial")
    class MainPanel extends JPanel{
        @Override
        public Dimension getPreferredSize() {
            // TODO Auto-generated method stub
            return new Dimension(400,300);
        }
    }

    class CustomMouseListener extends MouseAdapter{
        @Override
        public void mouseClicked(MouseEvent e) {
            System.out.println("Click: " + e.getPoint().getX() + " , " + e.getPoint().getY());
        }

        @Override
        public void mousePressed(MouseEvent e) {
            System.out.println("Press: " + e.getPoint().getX() + " , " + e.getPoint().getY());
        }

        @Override
        public void mouseReleased(MouseEvent e) {
            System.out.println("Release: " + e.getPoint().getX() + " , " + e.getPoint().getY());
        }

        @Override
        public void mouseDragged(MouseEvent e) {
            System.out.println("Drag: " + e.getPoint().getX() + " , " + e.getPoint().getY());
        }

        @Override
        public void mouseMoved(MouseEvent e) {
            System.out.println("MouseMove: " + e.getPoint().getX() + " , " + e.getPoint().getY());
        }
    }
}

不需要任何鼠标操作就可以获得位置吗？例如，我可以使用面板。getPointerLocation可随时获取此信息

提前感谢您的帮助

Answer 1

定义一个新的界面，以便听者可以向面板提供反馈：

public interface PointHolder {
    /**
     * Pass the new mouse location.
     * Pass null if the mouse left the panel
     */
    public void setPoint(Point newpoint);
}

让主面板实现它：

public MainPanel extends JPanel implements PointHolder {
    private Point lastpoint;
    @Override
    public void setPoint(Point newpoint) {
        lastpoint=newpoint;
    }
    public Point getPointerLocation() {
        return lastpoint;
    }
}

向CustomMouseListener添加构造函数：

public CustomMouseListener {
    PointHolder holder;
    public CustomMouseListener(PointHolder holder) {
       this.holder=holder;
    }

    @Override
    public void mouseMoved(MouseEvent e) {
        holder.setPoint(e.getPoint());

        System.out.println("MouseMove: " + e.getPoint().getX() + " , " + e.getPoint().getY());
    }

    @Override
    public void mouseExited(MouseEvent e)
    {
        holder.setPoint(null);
    }
}

主要是：

    MainPanel mainPanel = new MainPanel();
    CustomMouseListener listener=new CustomMouseListener(mainPanel);
    mainPanel.addMouseListener(listener);
    mainPanel.addMouseMotionListener(listener);

从现在起，您可以调用mainPanel.getPointerLocation()，如果鼠标不再位于面板上方，它将返回null

Answer 2

使用鼠标信息。getPointerInfo（）。getLocation（）随时获取当前鼠标位置