写一个图片验证算数形式的Java类

以下是一个简单的Java类，用于生成带有算术表达式的图片验证：

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;

public class ArithmeticCaptcha {
    private static final int WIDTH = 120;  // 图片宽度
    private static final int HEIGHT = 40;  // 图片高度
    private static final int FONT_SIZE = 20;  // 字体大小
    private static final int STR_LENGTH = 4;  // 验证码长度
    private static final int MAX_NUM = 10;  // 随机数最大值

    public static BufferedImage createImage() {
        // 创建图片缓冲区
        BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);

        // 获取图形上下文
        Graphics g = image.getGraphics();

        // 设置背景颜色
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, WIDTH, HEIGHT);

        // 生成随机数和运算符
        Random random = new Random();
        int num1 = random.nextInt(MAX_NUM);
        int num2 = random.nextInt(MAX_NUM);
        int operatorIndex = random.nextInt(2);
        char operator = operatorIndex == 0 ? '+' : '-';

        // 计算结果
        int result = operatorIndex == 0 ? num1 + num2 : num1 - num2;

        // 将算式绘制到图片上
        g.setColor(Color.BLACK);
        g.setFont(new Font("Arial", Font.BOLD, FONT_SIZE));
        String expression = num1 + " " + operator + " " + num2 + " = ?";
        g.drawString(expression, 10, 25);

        // 绘制干扰线
        int lineCount = 5;
        for (int i = 0; i < lineCount; i++) {
            int x1 = random.nextInt(WIDTH);
            int y1 = random.nextInt(HEIGHT);
            int x2 = random.nextInt(WIDTH);
            int y2 = random.nextInt(HEIGHT);
            g.drawLine(x1, y1, x2, y2);
        }

        // 释放图形上下文
        g.dispose();

        // 返回图片缓冲区
        return image;
    }
}

使用方法：

// 生成图片验证码
BufferedImage image = ArithmeticCaptcha.createImage();

// 将图片验证码输出到文件或响应流
ImageIO.write(image, "JPEG", new File("captcha.jpg"));