How to get http response.

public class HttpWebResponseUtility
    {
        public static string CreateGetHttpResponse(string url)
        {
            var response = CreateGetHttpResponse(url, null);
            Stream dataStream = response.GetResponseStream();
            StreamReader reader = new StreamReader(dataStream);
            string responseString = reader.ReadToEnd();
            return responseString;
        }

        public static string CreatePostHttpResponse(string url, IDictionary<string, string> parameters)
        {
            var response = CreatePostHttpResponse(url, parameters,null,System.Text.Encoding.UTF8);
            Stream dataStream = response.GetResponseStream();
            StreamReader reader = new StreamReader(dataStream);
            string responseString = reader.ReadToEnd();
            return responseString;
        }

        public static HttpWebResponse CreateGetHttpResponse(string url, int? timeout)
        {
            if (string.IsNullOrEmpty(url))
            {
                throw new ArgumentNullException("url");
            }
            var request = WebRequest.Create(url) as HttpWebRequest;
            request.Method = "GET";
            request.Proxy = null;
            request.Credentials = CredentialCache.DefaultCredentials;
            //allows for validation of SSL certificates 
            ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);

            if (timeout.HasValue)
            {
                request.Timeout = timeout.Value;
            }
            return request.GetResponse() as HttpWebResponse;
        }

        public static HttpWebResponse CreatePostHttpResponse(string url, IDictionary<string, string> parameters, int? timeout, Encoding requestEncoding)
        {
            if (string.IsNullOrEmpty(url))
            {
                throw new ArgumentNullException("url");
            }
            if (requestEncoding == null)
            {
                throw new ArgumentNullException("requestEncoding");
            }
            HttpWebRequest request = null;

            if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))
            {
                ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
                request = WebRequest.Create(url) as HttpWebRequest;
                request.Proxy = null;
                request.Credentials = CredentialCache.DefaultCredentials;
                request.ProtocolVersion = HttpVersion.Version10;
            }
            else
            {
                request = WebRequest.Create(url) as HttpWebRequest;
            }
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";

            if (timeout.HasValue)
            {
                request.Timeout = timeout.Value;
            }
            if (!(parameters == null || parameters.Count == 0))
            {
                StringBuilder buffer = new StringBuilder();
                int i = 0;
                foreach (string key in parameters.Keys)
                {
                    if (i > 0)
                    {
                        buffer.AppendFormat("&{0}={1}", key, parameters[key]);
                    }
                    else
                    {
                        buffer.AppendFormat("{0}={1}", key, parameters[key]);
                    }
                    i++;
                }
                byte[] data = requestEncoding.GetBytes(buffer.ToString());
                using (Stream stream = request.GetRequestStream())
                {
                    stream.Write(data, 0, data.Length);
                }
            }
            return request.GetResponse() as HttpWebResponse;
        }

        private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
        {
            return true; //总是接受
        }
    }