SpringBoot整合Kaptcha实现图片验证码加减乘除功能

<!-- https://mvnrepository.com/artifact/com.github.penggle/kaptcha -->
<dependency>
	<groupId>com.github.penggle</groupId>
	<artifactId>kaptcha</artifactId>
	<version>2.3.2</version>
</dependency>

package com.bangbang.tracesource.admin.conf;
import com.google.code.kaptcha.text.impl.DefaultTextCreator;
import java.util.Random;
public class MathKaptchaTextCreator extends DefaultTextCreator {
    @Override
    public String getText() {
        Random random = new Random();
        int x = random.nextInt(100);
        int y = random.nextInt(100);
        String[] operators = {"+", "-", "*", "/"};
        String operator = operators[random.nextInt(4)];
        String expression = x + operator + y;
        int result = 0;
        switch (operator) {
            case "+":
                result = x + y;
                break;
            case "-":
                result = x - y;
                break;
            case "*":
                result = x * y;
                break;
            case "/":
                result = y == 0 ? x : x / y;
                break;
        }
        return expression + "=?@" + result;
    }
}

import com.google.code.kaptcha.impl.DefaultKaptcha;
import com.google.code.kaptcha.util.Config;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;
import java.util.Properties;
@Component
public class KaptchaConfig {
    @Bean
    public DefaultKaptcha getDefaultKaptcha() {
        DefaultKaptcha defaultKaptcha = new DefaultKaptcha();
        Properties properties = new Properties();
        properties.setProperty("kaptcha.border", "yes");
        properties.setProperty("kaptcha.border.color", "105,179,90");
        properties.setProperty("kaptcha.textproducer.font.color", "black");
        properties.setProperty("kaptcha.image.width", "110");
        properties.setProperty("kaptcha.image.height", "40");
        properties.setProperty("kaptcha.textproducer.font.size", "35");
        properties.setProperty("kaptcha.session.key", "code");
        properties.setProperty("kaptcha.textproducer.impl", "com.shy.admin.conf.MathKaptchaTextCreator");
        properties.setProperty("kaptcha.textproducer.font.names", "宋体,楷体,微软雅黑");
        // 设置干扰线
        properties.setProperty("kaptcha.obscurificator.impl", "com.google.code.kaptcha.impl.FishEyeGimpy");
        Config config = new Config(properties);
        defaultKaptcha.setConfig(config);
        return defaultKaptcha;
    }
}

import com.google.code.kaptcha.impl.DefaultKaptcha;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
public class KaptchaController {
    @Autowired
    private DefaultKaptcha defaultKaptcha;
    @RequestMapping(value = "/kaptcha", method = RequestMethod.GET)
    public void getKaptcha(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse)
            throws IOException {
        byte[] captchaChallengeAsJpeg;
        ByteArrayOutputStream jpegOutputStream = new ByteArrayOutputStream();
        try {
            // 生产验证码字符串并保存到session中 eg: 3-2=?@1
            String createText = defaultKaptcha.createText();
            // capStr就是算术题 也就是用户看到的验证码
            String capStr = createText.substring(0, createText.lastIndexOf("@"));
            // code 就是算术的结果 也就是输入的验证码
            String code = createText.substring(createText.lastIndexOf("@") + 1);
            httpServletRequest.getSession().setAttribute("KAPTCHA_SESSION_KEY", code);
            // 使用生产的验证码字符串返回一个BufferedImage对象并转为byte写入到byte数组中
            BufferedImage challenge = defaultKaptcha.createImage(capStr);
            ImageIO.write(challenge, "jpg", jpegOutputStream);
        } catch (IllegalArgumentException e) {
            httpServletResponse.sendError(HttpServletResponse.SC_NOT_FOUND);
            return;
        }
        captchaChallengeAsJpeg = jpegOutputStream.toByteArray();
        httpServletResponse.setHeader("Cache-Control", "no-store");
        httpServletResponse.setHeader("Pragma", "no-cache");
        httpServletResponse.setDateHeader("Expires", 0);
        httpServletResponse.setContentType("image/jpeg");
        httpServletResponse.getOutputStream().write(captchaChallengeAsJpeg);
        httpServletResponse.getOutputStream().flush();
    }
}

// 生产验证码字符串并保存到session中 eg: 3-2=?@1
String createText = defaultKaptcha.createText();
// capStr就是算术题 也就是用户看到的验证码
String capStr = createText.substring(0, createText.lastIndexOf("@"));
// code 就是算术的结果 也就是输入的验证码
String code = createText.substring(createText.lastIndexOf("@") + 1);
httpServletRequest.getSession().setAttribute("KAPTCHA_SESSION_KEY", code);