引入依赖

<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-data-redis -->
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-redis</artifactId>
  <version>3.2.4</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.github.whvcse/easy-captcha -->
<dependency>
  <groupId>com.github.whvcse</groupId>
  <artifactId>easy-captcha</artifactId>
  <version>1.6.2</version>
</dependency>

编写相应前端实体vo

package com.orchids.springmybatisplus.model.entity;

import io.swagger.v3.oas.annotations.media.Schema;
import lombok.AllArgsConstructor;
import lombok.Data;

@Data
@Schema(description = "图像验证码")
@AllArgsConstructor
public class CaptchaVo {

    @Schema(description="验证码图片信息")
    private String image;

    @Schema(description="验证码key")
    private String key;
}

生成验证码

1. controller

@Controller
public class LoginController {
    @Autowired
    private LoginService loginService;
    @Operation(summary = "获取图形验证码")
    @GetMapping("login/captcha")
    public Result<CaptchaVo> getCaptcha() {
        CaptchaVo captcha = loginService.getCaptcha();
        return Result.ok(captcha);
    }
}

2. serviceimpl

@Service
public class LoginServiceImpl implements LoginService {
    @Autowired
    private StringRedisTemplate redisTemplate;
    @Override
    public CaptchaVo getCaptcha() {
        SpecCaptcha specCaptcha = new SpecCaptcha(100, 40, 4);
        String code = specCaptcha.text().toLowerCase();
        String key = RedisConstant.ADMIN_LOGIN_PREFIX + UUID.randomUUID();
        String image = specCaptcha.toBase64();

        redisTemplate.opsForValue().set(key,code,60, TimeUnit.SECONDS);
        return new CaptchaVo(image, key);
    }
}

因为需要使用redis所以 需要在yml中配置redis

spring:
    data:
        redis:
          host: localhost
          port: 6379
          database: 0

测试