C#带参数的POST请求方式

        public string Post(string url, Dictionary<string, string> dic,string body="")
        {
            string result = "";
            StringBuilder builder = new StringBuilder();
            foreach (var item in dic)
            {
               
                builder.AppendFormat("{0}={1}", item.Key, item.Value);
                builder.Append("&");
            }
            url += "?"+builder.ToString()+"t="+DateTime.Now.Second;
            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
            req.Method = "POST";
            req.ContentType = "application/json";
            //这个可以添加head
            //req.Headers.Add("header", "header");
            #region 添加Body 内容

            byte[] data = Encoding.UTF8.GetBytes(body);
            req.ContentLength = data.Length;
            using (Stream reqStream = req.GetRequestStream())
            {
                reqStream.Write(data, 0, data.Length);
                reqStream.Close();
            }
            #endregion
            HttpWebResponse resp = (HttpWebResponse)req.GetResponse();
            Stream stream = resp.GetResponseStream();
            //获取响应内容
            using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
            {
                result = reader.ReadToEnd();
            }
            return result;
        }