public async Task GetVerifyCode()
        {
            Response.ContentType = "image/jpeg";
            using (var stream = VerifyCodeHelper.Create(out string code))
            {
                var buffer = stream.ToArray();

                // 将验证码的token放入cookie
                Response.Cookies.Append(VERFIY_CODE_TOKEN_COOKIE_NAME, await SecurityServices.GetVerifyCodeToken(code));

                await Response.Body.WriteAsync(buffer, 0, buffer.Length);
            }
        }