请给出java边界标志算法绘制多边形的代码

以下是Java中实现边界标志算法绘制多边形的代码：

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
 
public class PolygonDrawer extends JFrame {
    private ArrayList<Point> points;
    private int mouseX, mouseY;
    private boolean mouseDown = false;
    private boolean firstPoint = true;
 
    public PolygonDrawer() {
        super("Polygon Drawer");
        setSize(640, 480);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
        // create the list to hold the points
        points = new ArrayList<Point>();
 
        // add the mouse listener for the drawing area
        JPanel panel = new JPanel() {
            public void paintComponent(Graphics g) {
                super.paintComponent(g);
                drawPolygon(g);
            }
        };
        panel.setBackground(Color.WHITE);
        panel.addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent e) {
                mouseX = e.getX();
                mouseY = e.getY();
                mouseDown = true;
                if (firstPoint) {
                    points.add(new Point(mouseX, mouseY));
                    firstPoint = false;
                }
            }
 
            public void mouseReleased(MouseEvent e) {
                mouseDown = false;
            }
        });
        panel.addMouseMotionListener(new MouseMotionAdapter() {
            public void mouseMoved(MouseEvent e) {
                mouseX = e.getX();
                mouseY = e.getY();
                repaint();
            }
 
            public void mouseDragged(MouseEvent e) {
                mouseX = e.getX();
                mouseY = e.getY();
                if (mouseDown) {
                    points.add(new Point(mouseX, mouseY));
                    repaint();
                }
            }
        });
 
        getContentPane().add(panel);
        setVisible(true);
    }
 
    public static void main(String[] args) {
        new PolygonDrawer();
    }
 
    private void drawPolygon(Graphics g) {
        if (points.size() > 0) {
            int[] xPoints = new int[points.size()];
            int[] yPoints = new int[points.size()];
            for (int i = 0; i < points.size(); i++) {
                xPoints[i] = points.get(i).x;
                yPoints[i] = points.get(i).y;
            }
            g.drawPolygon(xPoints, yPoints, points.size());
        }
        if (mouseDown) {
            if (points.size() > 0) {
                int[] xPoints = new int[points.size() + 1];
                int[] yPoints = new int[points.size() + 1];
                for (int i = 0; i < points.size(); i++) {
                    xPoints[i] = points.get(i).x;
                    yPoints[i] = points.get(i).y;
                }
                xPoints[points.size()] = mouseX;
                yPoints[points.size()] = mouseY;
                g.drawPolyline(xPoints, yPoints, points.size() + 1);
            } else {
                g.drawLine(mouseX, mouseY, mouseX, mouseY);
            }
        }
    }
}

希望对你有帮助！