public static string HttpPost(string url, string body)        {            //ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);            Encoding encoding = Encoding.UTF8;            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);            request.Method = "POST";            request.Accept = "text/html, application/xhtml+xml, */*";            request.ContentType = "application/json";                   byte[] buffer = encoding.GetBytes(body);            request.ContentLength = buffer.Length;            request.GetRequestStream().Write(buffer, 0, buffer.Length);            HttpWebResponse response = (HttpWebResponse)request.GetResponse();            using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))            {                return reader.ReadToEnd();            }        }        public static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)        {            return true; //总是接受          }