1、在pom文件中先导入生成图像的依赖包

<dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>kaptcha-spring-boot-starter</artifactId>
            <version>1.0.0</version>
        </dependency>

2、在config写配置类

@Configuration
public class CaptchaConfig {
    /**
     * 验证码配置
     * Kaptcha配置类名
     * 
     * @return
     */
    @Bean
    @Qualifier("captchaProducer")
    public DefaultKaptcha kaptcha() {
        DefaultKaptcha kaptcha = new DefaultKaptcha();
        Properties properties = new Properties();
        //验证码个数
        properties.setProperty(Constants.KAPTCHA_TEXTPRODUCER_CHAR_LENGTH, "4");
        //字体间隔
        properties.setProperty(Constants.KAPTCHA_TEXTPRODUCER_CHAR_SPACE,"8");
        //干扰线颜色
        //干扰实现类
        properties.setProperty(Constants.KAPTCHA_NOISE_IMPL, "com.google.code.kaptcha.impl.NoNoise");
        //图片样式
        properties.setProperty(Constants.KAPTCHA_OBSCURIFICATOR_IMPL, "com.google.code.kaptcha.impl.WaterRipple");
        //文字来源
        properties.setProperty(Constants.KAPTCHA_TEXTPRODUCER_CHAR_STRING, "0123456789");

        Config config = new Config(properties);
        kaptcha.setConfig(config);
        return kaptcha;
    }
}

3、配置好redis相关的配置

4、存入redis

1. 根据请求获取客户ip作为key，方法如下：

2. **
        * 获取ip
        * @param request
        * @return
        */
       public static String getIpAddr(HttpServletRequest request) {
           String ipAddress = null;
           try {
               ipAddress = request.getHeader("x-forwarded-for");
               if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
                   ipAddress = request.getHeader("Proxy-Client-IP");
               }
               if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
                   ipAddress = request.getHeader("WL-Proxy-Client-IP");
               }
               if (ipAddress == null || ipAddress.length() == 0 || "unknown".equalsIgnoreCase(ipAddress)) {
                   ipAddress = request.getRemoteAddr();
                   if (ipAddress.equals("127.0.0.1")) {
                       // 根据网卡取本机配置的IP
                       InetAddress inet = null;
                       try {
                           inet = InetAddress.getLocalHost();
                       } catch (UnknownHostException e) {
                           e.printStackTrace();
                       }
                       ipAddress = inet.getHostAddress();
                   }
               }
               // 对于通过多个代理的情况，第一个IP为客户端真实IP,多个IP按照','分割
               if (ipAddress != null && ipAddress.length() > 15) {
                   // "***.***.***.***".length()
                   // = 15
                   if (ipAddress.indexOf(",") > 0) {
                       ipAddress = ipAddress.substring(0, ipAddress.indexOf(","));
                   }
               }
           } catch (Exception e) {
               ipAddress="";
           }
           return ipAddress;
       }

5、controller类编写

@RestController
@RequestMapping("/api/v1/captchar")
public class CaptCharController {

    @Autowired
    private RedisTemplate redisTemplate;

    @Autowired
    private Producer captchaProducer;  //captchaProducer和配置文件的@Qualifier("captchaProducer")名字相同才可以

@GetMapping("get_captcha") public void getCaptChar(HttpServletRequest request, HttpServletResponse response){ String producerText = captchaProducer.createText(); String key = getKey(request); //设置过期时间为10分钟 redisTemplate.opsForValue().set(key,producerText,10, TimeUnit.MINUTES); BufferedImage image = captchaProducer.createImage(producerText); ServletOutputStream outputStream = null; try { outputStream = response.getOutputStream(); ImageIO.write(image,"jpg",outputStream); outputStream.flush(); outputStream.close(); }catch (Exception e){ e.fillInStackTrace(); } } 
//获取key的值
    private String getKey(HttpServletRequest request){
        String ipAddr = CommonUtil.getIpAddr(request);
        String header = request.getHeader("User-Agent");
        String key = "user-service:captcha:"+CommonUtil.MD5(ipAddr+header);
        return key;
    }
}