后台web请求代码(含https,json提交）

namespace  XXXX.Utilites
{
    using System;
    using System.Collections.Generic;
    using System.IO;
    using System.IO.Compression;
    using System.Net;
    using System.Net.Security;
    using System.Security.Cryptography.X509Certificates;
    using System.Text;

    public class PostHttpResponse
    {
        #region Static Field
        private static readonly string DefaultUserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)";
        #endregion

        #region public Method
        public static string PostHttpResponseJson(string url)
        {
            string json = string.Empty;
            Encoding encoding = Encoding.UTF8;
            HttpWebResponse Response = CreatePostHttpResponseJson(url,null,null, null, null, encoding, null);
            json = GetStream(Response, encoding);
            return json;
        }

        public static string PostHttpResponseJson(string url, string  postJson)
        {
            string json = string.Empty;
            Encoding encoding = Encoding.UTF8;
            HttpWebResponse Response = CreatePostHttpResponseJson(url, postJson, null, null, null, encoding, null);
            json = GetStream(Response, encoding);
            return json;
        }

   

        /// <summary>
        /// 创建POST方式Json数据的HTTP请求（包括了https站点请求） 
        /// </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 CreatePostHttpResponseJson(string url, string postJson,string parameters, int? timeout, string userAgent, Encoding requestEncoding, string referer)
        {
            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
            {
                request = WebRequest.Create(url) as HttpWebRequest;
            }


            request.Method = "POST";
            //服务端 判断 客户端 提交的是否是 JSON数据 时
            request.ContentType = "application/json;charset=UTF-8";
            request.KeepAlive = true;

            if (!string.IsNullOrEmpty(userAgent))
            {
                request.UserAgent = userAgent;
            }
            else
            {
                request.UserAgent = DefaultUserAgent;
            }

            if (timeout.HasValue)
            {
                request.Timeout = timeout.Value;
            }

            //如果需要POST数据  
            #region post parameter  类似querystring格式
            if (parameters != null)
            {
                byte[] data = requestEncoding.GetBytes(parameters);
                using (Stream stream = request.GetRequestStream())
                {
                    stream.Write(data, 0, data.Length);
                    stream.Close();
                }
            }
            #endregion

            #region post json
            if (!string.IsNullOrEmpty(postJson))
            {
                using (var streamWriter = new StreamWriter(request.GetRequestStream()))
                {
                    //string json = "{\"user\":\"test\"," +
                    //              "\"password\":\"bla\"}";

                    streamWriter.Write(postJson);
                    streamWriter.Flush();
                    streamWriter.Close();
                }
            }
            #endregion


            if (!string.IsNullOrEmpty(referer))
            {
                request.Referer = referer;
            }

            HttpWebResponse response = request.GetResponse() as HttpWebResponse;

            if (request.CookieContainer != null)
            {
                response.Cookies = request.CookieContainer.GetCookies(request.RequestUri);
            }

            return response;
        }

        #endregion

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

        /// <summary>
        /// 将response转换成文本
        /// </summary>
        /// <param name="response"></param>
        /// <param name="encoding"></param>
        /// <returns></returns>
        private static string GetStream(HttpWebResponse response, Encoding encoding)
        {
            try
            {
                if (response.StatusCode == HttpStatusCode.OK)
                {
                    switch (response.ContentEncoding.ToLower())
                    {
                        case "gzip":
                            {
                                string result = Decompress(response.GetResponseStream(), encoding);
                                response.Close();
                                return result;
                            }
                        default:
                            {
                                using (StreamReader sr = new StreamReader(response.GetResponseStream(), encoding))
                                {
                                    string result = sr.ReadToEnd();
                                    sr.Close();
                                    sr.Dispose();
                                    response.Close();
                                    return result;
                                }
                            }
                    }
                }
                else
                {
                    response.Close();
                }
            }
            catch (Exception e)
            {
                throw e;
            }
            return "";
        }

        private static string Decompress(Stream stream, Encoding encoding)
        {
            byte[] buffer = new byte[100];
            //int length = 0;

            using (GZipStream gz = new GZipStream(stream, CompressionMode.Decompress))
            {
                //GZipStream gzip = new GZipStream(res.GetResponseStream(), CompressionMode.Decompress);
                using (StreamReader reader = new StreamReader(gz, encoding))
                {
                    return reader.ReadToEnd();
                }
                /*
                using (MemoryStream msTemp = new MemoryStream())
                {
                    //解压时直接使用Read方法读取内容，不能调用GZipStream实例的Length等属性，否则会出错：System.NotSupportedException: 不支持此操作；
                    while ((length = gz.Read(buffer, 0, buffer.Length)) != 0)
                    {
                        msTemp.Write(buffer, 0, length);
                    }

                    return encoding.GetString(msTemp.ToArray());
                }
                 * */
            }
        }

        #endregion
    }
}