C#调用SAP S4/HANA Gateway Service

        private Model.APIReturn ZOBIAPI(string PlantCode, DateTime DocDate)
        {
            Model.APIReturn ret = new Model.APIReturn();

            string sDocDate = GetTimestamp(DocDate.ToUniversalTime()).ToString();

            string userid = "";
            string password = "";
            string url = "";
            //url = "http://10.29.10.110:8000/sap/opu/odata/sap/ZODATA_ZOBI012_SRV/HeaderSet?sap-client=100";//测试环境
            url = "http://10.29.10.126:8000/sap/opu/odata/sap/ZODATA_ZOBI012_SRV/HeaderSet?sap-client=800";//正式环境
            string token = "";
            string json = "";
            string authorization = "Basic " + Convert.ToBase64String(Encoding.UTF8.GetBytes(userid + ":" + password));

            #region 通过 Headers-authorization 方式验证 Basic
            System.Net.HttpWebRequest request1 = System.Net.HttpWebRequest.Create(url) as System.Net.HttpWebRequest;
            request1.Method = "GET";
            request1.Headers.Add("authorization", authorization);
            request1.Headers.Add("x-csrf-token", "fetch");
            request1.CookieContainer = new System.Net.CookieContainer(); //没有Container就不能保存这次请求的Cookie，没有第一次的Cookie，第二次调用的时候会提示403

            using (System.Net.HttpWebResponse response1 = request1.GetResponse() as System.Net.HttpWebResponse)
            {
                token = response1.GetResponseHeader("x-csrf-token");
                #region 调用API
                System.Net.HttpWebRequest requestAPI = System.Net.HttpWebRequest.Create(url) as System.Net.HttpWebRequest;
                requestAPI.Method = "POST";
                requestAPI.Headers.Add("x-csrf-token", token); //x-csrf-token方式需要先从服务器用GET方式取得token
                requestAPI.ContentType = "application/json"; //用来指定提交给API的内容格式
                requestAPI.Accept = "application/json"; //用来指定API返回的内容格式
                requestAPI.CookieContainer = new System.Net.CookieContainer(); //new一个Container是为了将第一次的Cookie再次使用
                requestAPI.CookieContainer.Add(response1.Cookies); //将第一次的Cookie作为第二次再使用不然服务器会提示403
                json = @"{""ItemsSet"":[{""DocDate"":""\/Date(" + sDocDate + @")\/"",""DocDateAbc"":""\/Date(" + sDocDate + @")\/"",""PlantCode"":""" + PlantCode + @"""}]}";
                using (System.IO.StreamWriter sw = new System.IO.StreamWriter(requestAPI.GetRequestStream()))
                {
                    sw.Write(json);
                }
                using (System.Net.HttpWebResponse hwRespAPI = requestAPI.GetResponse() as System.Net.HttpWebResponse)
                {
                    System.IO.StreamReader sr = new System.IO.StreamReader(hwRespAPI.GetResponseStream());
                    string resultJson = sr.ReadToEnd();
                    ret = Newtonsoft.Json.JsonConvert.DeserializeObject<Model.APIReturn>(resultJson);
                }
                #endregion
            }
            #endregion

            return ret;
        }