gold-java/src/main/java/com/example/demo/controller/coin/CaptchaController.java

// com.example.demo.controller.CaptchaController.java
package com.example.demo.controller.coin;

import com.google.code.kaptcha.Producer;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.concurrent.TimeUnit;

@RestController
public class CaptchaController {

    @Autowired
    private Producer kaptchaProducer;

    @Autowired
    private StringRedisTemplate redisTemplate;

    /**
     * 获取图形验证码
     * @param uuid 前端生成的唯一标识，用于关联验证码
     */
    @GetMapping("/captcha")
    public void captcha(@RequestParam String uuid, HttpServletResponse response) throws IOException {
        if (uuid == null || uuid.trim().isEmpty()) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST, "uuid is required");
            return;
        }

        // 生成验证码文本和图片
        String code = kaptchaProducer.createText();
        BufferedImage image = kaptchaProducer.createImage(code);

        // 存入 Redis，5分钟过期
        redisTemplate.opsForValue().set("CAPTCHA:" + uuid, code, 5, TimeUnit.MINUTES);

        // 输出图片
        response.setHeader("Cache-Control", "no-store");
        response.setContentType("image/jpeg");
        ImageIO.write(image, "jpg", response.getOutputStream());
    }
}