pig-mesh/easy-captcha

@Controller
public class CaptchaController {
    
    @RequestMapping("/captcha")
    public void captcha(HttpServletRequest request, HttpServletResponse response) throws Exception {
        // 使用 Jakarta 时用 CaptchaJakartaUtil
        CaptchaUtil.out(request, response);
    }
}

@Controller
public class LoginController {
    
    @PostMapping("/login")
    public JsonResult login(String username, String password, String verCode) {
        // 使用 Jakarta 时用 CaptchaJakartaUtil
        if (!CaptchaUtil.ver(verCode, request)) {
            CaptchaUtil.clear(request);  // 清除session中的验证码
            return JsonResult.error("验证码不正确");
        }
    }   
}

@Controller
public class CaptchaController {
    
    @RequestMapping("/captcha")
    public void captcha(HttpServletRequest request, HttpServletResponse response) throws Exception {
        // 设置位数
        CaptchaUtil.out(5, request, response);
        // 设置宽、高、位数
        CaptchaUtil.out(130, 48, 5, request, response);
        
        // 使用gif验证码
        GifCaptcha gifCaptcha = new GifCaptcha(130,48,4);
        CaptchaUtil.out(gifCaptcha, request, response);
    }
}

@Controller
public class CaptchaController {
    
    @RequestMapping("/captcha")
    public void captcha(HttpServletRequest request, HttpServletResponse response) throws Exception {
        // 设置请求头为输出图片类型
        response.setContentType("image/gif");
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);
        
        // 三个参数分别为宽、高、位数
        SpecCaptcha specCaptcha = new SpecCaptcha(130, 48, 5);
        // 设置字体
        specCaptcha.setFont(new Font("Verdana", Font.PLAIN, 32));  // 有默认字体，可以不用设置
        // 设置类型，纯数字、纯字母、字母数字混合
        specCaptcha.setCharType(Captcha.TYPE_ONLY_NUMBER);
        
        // 验证码存入session
        request.getSession().setAttribute("captcha", specCaptcha.text().toLowerCase());
        
        // 输出图片流
        specCaptcha.out(response.getOutputStream());
    }
    
    @PostMapping("/login")
    public JsonResult login(String username,String password,String verCode){
        // 获取session中的验证码
        String sessionCode = request.getSession().getAttribute("captcha");
        // 判断验证码
        if (verCode==null || !sessionCode.equals(verCode.trim().toLowerCase())) {
            return JsonResult.error("验证码不正确");
        }
    }  
}

public class Test {
    
    public static void main(String[] args) {
        // png类型
        SpecCaptcha captcha = new SpecCaptcha(130, 48);
        captcha.text();  // 获取验证码的字符
        captcha.textChar();  // 获取验证码的字符数组
        
        // gif类型
        GifCaptcha captcha = new GifCaptcha(130, 48);
        
        // 中文类型
        ChineseCaptcha captcha = new ChineseCaptcha(130, 48);
        
        // 中文gif类型
        ChineseGifCaptcha captcha = new ChineseGifCaptcha(130, 48);
        
        // 算术类型
        ArithmeticCaptcha captcha = new ArithmeticCaptcha(130, 48);
        captcha.setLen(3);  // 几位数运算，默认是两位
        captcha.getArithmeticString();  // 获取运算的公式：3+2=?
        captcha.text();  // 获取运算的结果：5
        captcha.supportAlgorithmSign(2); // 可设置支持的算法：2 表示只生成带加减法的公式
        captcha.setDifficulty(50); // 设置计算难度，参与计算的每一个整数的最大值
        captcha.out(outputStream);  // 输出验证码
        //简单算术类型 SimpleArithmeticCaptcha,用法同ArithmeticCaptcha,只支持加减，计算结果为正整数
    }
}

    ArithmeticCaptcha arithmeticCaptcha=new ArithmeticCaptcha();
    arithmeticCaptcha.supportAlgorithmSign(5);

    SpecCaptcha captcha=new SpecCaptcha(130,48,5);
    captcha.setCharType(Captcha.TYPE_ONLY_NUMBER);

@Controller
public class CaptchaController {
    @Autowired
    private RedisUtil redisUtil;
    
    @ResponseBody
    @RequestMapping("/captcha")
    public JsonResult captcha(HttpServletRequest request, HttpServletResponse response) throws Exception {
        SpecCaptcha specCaptcha = new SpecCaptcha(130, 48, 5);
        String verCode = specCaptcha.text().toLowerCase();
        String key = UUID.randomUUID().toString();
        // 存入redis并设置过期时间为30分钟
        redisUtil.setEx(key, verCode, 30, TimeUnit.MINUTES);
        // 将key和base64返回给前端
        return JsonResult.ok().put("key", key).put("image", specCaptcha.toBase64());
    }
    
    @ResponseBody
    @PostMapping("/login")
    public JsonResult login(String username,String password,String verCode,String verKey){
        // 获取redis中的验证码
        String redisCode = redisUtil.get(verKey);
        // 判断验证码
        if (verCode==null || !redisCode.equals(verCode.trim().toLowerCase())) {
            return JsonResult.error("验证码不正确");
        }
    }  
}