第一次，我的csrf_token为空

Question

我有一个用于获取csrf_token的GET方法。我第一次调用该方法时收到null吗？

@GetMapping("check/mobile/{mobile}/otp/{otp}")
  public Response checkOtp(@PathVariable String mobile, @PathVariable int otp) {
    return otpService.checkOtp(mobile, otp);
  }

 public Response checkOtp(String mobile, int otp) {
    Response response = new Response();

    response.setStatus(ResponseStatusEnum.SUCCESS);
    response.setDescription(messages.get("otp.success"));
    Authentication authentication = new UsernamePasswordAuthenticationToken(mobile, "",
        AuthorityUtils.createAuthorityList("ROLE_USER"));
    SecurityContextHolder.getContext().setAuthentication(authentication);
    response.setData(getCsrfToken());

    return response;
  }

private CsrfToken getCsrfToken() {
    ServletRequestAttributes attr = (ServletRequestAttributes) RequestContextHolder
        .currentRequestAttributes();
    HttpSession session = attr.getRequest().getSession();
    return (CsrfToken) session.getAttribute(
        "org.springframework.security.web.csrf.HttpSessionCsrfTokenRepository.CSRF_TOKEN");
  }