/// <summary>  

        /// 创建POST方式的HTTP请求  

        /// </summary>  

        /// <param name="url">请求的URL</param>  

        /// <param name="parameters">随同请求POST的参数名称及参数值字典</param>  

        /// <param name="timeout">请求的超时时间</param>  

        /// <param name="userAgent">请求的客户端浏览器信息，可以为空</param>  

        /// <param name="requestEncoding">发送HTTP请求时所用的编码</param>  

        /// <param name="cookies">随同HTTP请求发送的Cookie信息，如果不需要身份验证可以为空</param>  

        /// <returns></returns>  

        public static HttpWebResponse CreatePostHttpResponse(string url, IDictionary<string, string> parameters, int? timeout, string userAgent, Encoding requestEncoding, CookieCollection cookies)

        {

            if (string.IsNullOrEmpty(url))

            {

                throw new ArgumentNullException("url");

            }

            if (requestEncoding == null)

            {

                throw new ArgumentNullException("requestEncoding");

            }

            HttpWebRequest request = null;

            //如果是发送HTTPS请求  

            if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))

            {

                ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);

                request = WebRequest.Create(url) as HttpWebRequest;

                request.ProtocolVersion = HttpVersion.Version10;

            }

            else

            {