<dependency>
     <groupId>com.google.code.kaptcha</groupId>
     <artifactId>kaptcha</artifactId>
     <version>2.3</version>
 </dependency>

  <dependency>
      <groupId>com.github.penggle</groupId>
      <artifactId>kaptcha</artifactId>
      <version>2.3.2</version>
  </dependency>

@Component
public class KaptchaConfig {
    @Bean
    public DefaultKaptcha getDefaultKaptcha(){
        com.google.code.kaptcha.impl.DefaultKaptcha defaultKaptcha = new com.google.code.kaptcha.impl.DefaultKaptcha();
        Properties properties = new Properties();
        properties.put("kaptcha.border", "no");
        properties.put("kaptcha.textproducer.font.color", "red");
        properties.put("kaptcha.image.width", "213");
        properties.put("kaptcha.image.height", "88");
        properties.put("kaptcha.textproducer.font.size", "45");
        properties.put("kaptcha.session.key", "verifyCode");
        properties.put("kaptcha.textproducer.char.space", "6");
        properties.put("kaptcha.obscurificator.impl", "com.google.code.kaptcha.impl.WaterRipple");
       // properties.put("kaptcha.textproducer.font.names", "宋體,楷體,微軟雅黑");
        properties.put("kaptcha.background.clear.from", "yellow");
        properties.put("kaptcha.background.clear.to", "green");
        Config config = new Config(properties);
        defaultKaptcha.setConfig(config);
        return defaultKaptcha;
    }
}

@GetMapping("/login/getVerifyCode")
    public void getVerifyCode(String loginKey,
                              HttpServletRequest httpServletRequest,
                              HttpServletResponse httpServletResponse) {
        try {
            log.warn("query verify Code" + loginKey);
            loadService.getVerifyCode(loginKey, httpServletRequest, httpServletResponse);
        } catch (Exception e) {
            log.error("get verify Code failed :", e);
        }
    }

public void getVerifyCode(String loginKey, HttpServletRequest httpServletRequest,
                              HttpServletResponse httpServletResponse) throws IOException {
        ByteArrayOutputStream imgOutputStream = new ByteArrayOutputStream();
        try {
            //生產(chǎn)驗(yàn)證碼字符串并保存到session中
            String verifyCode = captchaProducer.createText();
            // httpServletRequest.getSession().setAttribute("verifyCode", verifyCode);  // 寫入會(huì)話
            //redisCache.setVerifyInfo(loginKey, verifyCode);   //寫入redis
            captchaMap.put(loginKey, verifyCode);//寫入內(nèi)存
            log.warn("reset verify code key {}, code {}", loginKey, verifyCode);
            BufferedImage challenge = captchaProducer.createImage(verifyCode);
            ImageIO.write(challenge, "jpg", imgOutputStream);
        } catch (IllegalArgumentException | IOException e) {
            httpServletResponse.sendError(HttpServletResponse.SC_NOT_FOUND);
            return;
        }
        byte[] captchaOutputStream = imgOutputStream.toByteArray();
        httpServletResponse.setHeader("Cache-Control", "no-store");
        httpServletResponse.setHeader("Pragma", "no-cache");
        httpServletResponse.setDateHeader("Expires", 0);
        httpServletResponse.setContentType("image/jpeg");
        try (ServletOutputStream responseOutputStream = httpServletResponse.getOutputStream()) {
            responseOutputStream.write(captchaOutputStream);
            responseOutputStream.flush();
        } catch (IOException ex) {
            log.error("find ex in create a new verify Code", ex);
        }
    }

 java.lang.NullPointerException: null
         at sun.awt.FontConfiguration.getVersion(FontConfiguration.java:1264)
         at sun.awt.FontConfiguration.readFontConfigFile(FontConfiguration.java:219)
         at sun.awt.FontConfiguration.init(FontConfiguration.java:107)
 .....