如何在Java Swing中拖动和绘制两点间的直线

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class LineDrawingPanel extends JPanel {
    private Point startPoint;
    private Point endPoint;

    public LineDrawingPanel() {
        // 添加鼠标事件监听器
        addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent e) {
                startPoint = e.getPoint();
            }

            public void mouseReleased(MouseEvent e) {
                endPoint = e.getPoint();
                repaint();
            }
        });

        addMouseMotionListener(new MouseMotionAdapter() {
            public void mouseDragged(MouseEvent e) {
                endPoint = e.getPoint();
                repaint();
            }
        });
    }

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (startPoint != null && endPoint != null) {
            g.drawLine(startPoint.x, startPoint.y, endPoint.x, endPoint.y);
        }
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Line Drawing");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(400, 400);

        LineDrawingPanel panel = new LineDrawingPanel();
        frame.add(panel);

        frame.setVisible(true);
    }
}