C# POST方式提交数据，接收方式，使用Request.Form[""]或Request[""]来获取

  /// <summary>
        /// 调用接口
        /// </summary>
        /// <param name="url"></param>
        /// <param name="dic">提交的参数</param>
        /// <returns></returns>
        public string Post(string url  , Dictionary<string, string> dic)
        {
            string result = "";

            //添加Post 参数
            System.Text.StringBuilder builder = new System.Text.StringBuilder();
            int i = 0;
            foreach (var item in dic)
            {
                if (i > 0)
                    builder.Append("&");
                builder.AppendFormat("{0}={1}", item.Key, item.Value);
                i++;
            }
            byte[] postData = System.Text.Encoding.UTF8.GetBytes(builder.ToString());

            System.Net.HttpWebRequest _webRequest = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(url);
            _webRequest.Method = "POST";
            //_webRequest.ContentType = "application/json";
            //内容类型  
            _webRequest.ContentType = "application/x-www-form-urlencoded";
            _webRequest.Timeout = 1000 * 30;
            _webRequest.ContentLength = postData.Length;

            using (System.IO.Stream reqStream = _webRequest.GetRequestStream())
            {
                reqStream.Write(postData, 0, postData.Length);
                reqStream.Close();
            }

            System.Net.HttpWebResponse resp = (System.Net.HttpWebResponse)_webRequest.GetResponse();
            System.IO.Stream stream = resp.GetResponseStream();
            //获取响应内容
            using (System.IO.StreamReader reader = new System.IO.StreamReader(stream, System.Text.Encoding.UTF8))
            {
                result = reader.ReadToEnd();
            }
 
            return result;
        }

//调用接口
var para = new Dictionary<string, string>();
 para.Add("UserId", "33699");
 para.Add("pwd", "123456");
 string postResult = Post("http://", para);