/*

    *  url:POST请求地址,例如：url = "http://localhost:35229/ddn/GetPostData";

    *  postData:json格式的请求报文,例如：{"key1":"value1","key2":"value2"}

    */

     public static string PostUrl(string url, string postData)

        {

            string result = "";

            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);

            req.Method = "POST";

            req.TimeOut = "";//设置请求超时时间，单位为毫秒

            req.ContentType = "application/json";

            byte[] data = Encoding.UTF8.GetBytes(postData);

            req.ContentLength = data.Length;

            using (Stream reqStream = req.GetRequestStream())

            {

                reqStream.Write(data, , data.Length);

                reqStream.Close();

            }

            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;

        }