public void ConfigureServices(IServiceCollection services)

        {         

            services.AddControllers();

            services.Configure(options =>

            {

                // This lambda determines whether user consent for non-essential cookies is needed for a given request.

                options.CheckConsentNeeded = context => false;//这里要改为false，默认是true，true的时候session无效

                options.MinimumSameSitePolicy = SameSiteMode.None;

            });

            services.AddDistributedMemoryCache();

            services.AddSession(option =>

            {

                option.IOTimeout = TimeSpan.FromHours(1);

                option.IdleTimeout = TimeSpan.FromHours(1);

                option.Cookie.HttpOnly = true;

                // Make the session cookie essential

                option.Cookie.IsEssential = true;

                option.Cookie.Name = "XMECG";

                //默认cookie如果没有信息，会被清空，导致sessionid改变，所以先给个名字

            });

            services.AddMvc()

            .SetCompatibilityVersion(CompatibilityVersion.Version_3_0);

        }

 public void Configure(IApplicationBuilder app, IWebHostEnvironment env)

        {

          ............

            app.UseAuthorization();

          //启动SESSION

            app.UseSession();

            app.UseCookiePolicy();

   //支持获取IP地址

            app.UseForwardedHeaders(new ForwardedHeadersOptions { ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto });

  //End Sesson 

            app.UseEndpoints(endpoints =>

            {

                endpoints.MapControllers();

            });

        }

            if (HttpContext.Session.TryGetValue("USERID", out byte[] bytes))

            {

                theUserId = Encoding.UTF8.GetString(bytes);

            }

        private static CookieContainer cookie  = new CookieContainer();

           byte[] bs = Encoding.UTF8.GetBytes(theText);

            HttpWebRequest theRequest = (HttpWebRequest)HttpWebRequest.Create(url);

            theRequest.Method = "POST";

            theRequest.ContentType = "application/json;charset=utf-8";

            theRequest.ContentLength = bs.Length;

            theRequest.Headers.Set("Cookie", "cookie");

            theRequest.CookieContainer = cookie;

            using (Stream reqStream = theRequest.GetRequestStream())

            {

                reqStream.Write(bs, 0, bs.Length);

                reqStream.Close();

            }

            using (Stream reqStream = theRequest.GetRequestStream())

            {

                reqStream.Write(bs, 0, bs.Length);

                reqStream.Close();

            }

            using (WebResponse wr = theRequest.GetResponse())

            {

                Stream theResponseStream = wr.GetResponseStream();

                StreamReader theReader = new StreamReader(theResponseStream);

                string theOutPut = theReader.ReadToEnd();

                System.Text.UTF8Encoding converter = new System.Text.UTF8Encoding();

                string theBase642 = converter.GetString(Convert.FromBase64String(theOutPut));

             }