java 加减法验证码

以下是一个简单的 Java 加减法验证码生成器：

import java.util.Random;

public class CaptchaGenerator {
    private static final int MIN_NUM = 1;
    private static final int MAX_NUM = 10;
    private static final String[] OPERATORS = {"+", "-"};

    public static String generate() {
        Random random = new Random();
        int num1 = random.nextInt(MAX_NUM - MIN_NUM + 1) + MIN_NUM;
        int num2 = random.nextInt(MAX_NUM - MIN_NUM + 1) + MIN_NUM;
        String operator = OPERATORS[random.nextInt(OPERATORS.length)];
        int result;
        String captcha;

        if (operator.equals("+")) {
            result = num1 + num2;
            captcha = num1 + " + " + num2 + " = ?";
        } else {
            result = num1 - num2;
            captcha = num1 + " - " + num2 + " = ?";
        }

        captcha += " " + result;
        return captcha;
    }
}

使用方法：

String captcha = CaptchaGenerator.generate();

该代码会生成一个形如 "2 + 3 = ? 5" 的字符串作为验证码，其中 "?" 部分需要用户输入计算结果。