推荐一个很好用的HTTP操作类

 /// <summary>
 /// 类说明：HttpHelps类，用来实现Http访问，Post或者Get方式的，直接访问，带Cookie的，带证书的等方式，可以设置代理
 /// 重要提示：请不要自行修改本类，如果因为你自己修改后将无法升级到新版本。如果确实有什么问题请到官方网站提建议，
 /// 我们一定会及时修改
 /// 编码日期：2011-09-20
 /// 编 码 人：苏飞
 /// 联系方式：361983679
 /// 官方网址：http://www.sufeinet.com/thread-3-1-1.html
 /// 修改日期：2013-04-14
 /// </summary>
 using System;
 using System.Collections.Generic;
 using System.Text;
 using System.Net;
 using System.IO;
 using System.Text.RegularExpressions;
 using System.IO.Compression;
 using System.Security.Cryptography.X509Certificates;
 using System.Net.Security;

 namespace Common.PageHelper
 {
     /// <summary>
     /// Http连接操作帮助类
     /// </summary>
     public class HttpHelper
     {
         #region 预定义方法或者变更
         //默认的编码
         private Encoding encoding = Encoding.Default;
         //HttpWebRequest对象用来发起请求
         private HttpWebRequest request = null;
         //获取影响流的数据对象
         private HttpWebResponse response = null;
         /// <summary>
         /// 根据相传入的数据，得到相应页面数据
         /// </summary>
         /// <param name="objhttpitem">参数类对象</param>
         /// <returns>返回HttpResult类型</returns>
         private HttpResult GetHttpRequestData(HttpItem objhttpitem)
         {
             //返回参数
             HttpResult result = new HttpResult();
             try
             {
                 #region 得到请求的response
                 using (response = (HttpWebResponse)request.GetResponse())
                 {
                     result.StatusCode = response.StatusCode;
                     result.StatusDescription = response.StatusDescription;
                     result.Header = response.Headers;
                     if (response.Cookies != null)
                         result.CookieCollection = response.Cookies;
                     if (response.Headers["set-cookie"] != null)
                         result.Cookie = response.Headers["set-cookie"];
                     MemoryStream _stream = new MemoryStream();
                     //GZIIP处理
                     if (response.ContentEncoding != null && response.ContentEncoding.Equals("gzip", StringComparison.InvariantCultureIgnoreCase))
                     {
                         //开始读取流并设置编码方式
                         //new GZipStream(response.GetResponseStream(), CompressionMode.Decompress).CopyTo(_stream, 10240);
                         //.net4.0以下写法
                         _stream = GetMemoryStream(new GZipStream(response.GetResponseStream(), CompressionMode.Decompress));
                     }
                     else
                     {
                         //开始读取流并设置编码方式
                         //response.GetResponseStream().CopyTo(_stream, 10240);
                         //.net4.0以下写法
                         _stream = GetMemoryStream(response.GetResponseStream());
                     }
                     //获取Byte
                     byte[] RawResponse = _stream.ToArray();
                     _stream.Close();
                     //是否返回Byte类型数据
                     if (objhttpitem.ResultType == ResultType.Byte)
                         result.ResultByte = RawResponse;
                     //从这里开始我们要无视编码了
                     if (encoding == null)
                     {
                         Match meta = Regex.Match(Encoding.Default.GetString(RawResponse), "<meta([^<]*)charset=([^<]*)[\"']", RegexOptions.IgnoreCase);
                         string charter = (meta.Groups.Count > ) ? meta.Groups[].Value.ToLower() : string.Empty;
                         charter = charter.Replace("\"", "").Replace("'", "").Replace(";", "").Replace("iso-8859-1", "gbk");
                         if (charter.Length > )
                             encoding = Encoding.GetEncoding(charter);
                         else
                         {
                             if (string.IsNullOrEmpty(response.CharacterSet))
                                 encoding = Encoding.UTF8;
                             else
                                 encoding = Encoding.GetEncoding(response.CharacterSet);
                         }
                     }
                     //得到返回的HTML
                     result.Html = encoding.GetString(RawResponse);
                 }
                 #endregion
             }
             catch (WebException ex)
             {
                 //这里是在发生异常时返回的错误信息
                 response = (HttpWebResponse)ex.Response;
                 result.Html = ex.Message;
                 result.StatusCode = response.StatusCode;
                 result.StatusDescription = response.StatusDescription;
             }
             catch (Exception ex)
             {
                 result.Html = ex.Message;
             }
             if (objhttpitem.IsToLower)
                 result.Html = result.Html.ToLower();

             return result;
         }
         /// <summary>
         /// 4.0以下.net版本取数据使用
         /// </summary>
         /// <param name="streamResponse">流</param>
         private static MemoryStream GetMemoryStream(Stream streamResponse)
         {
             MemoryStream _stream = new MemoryStream();
             int Length = ;
             Byte[] buffer = new Byte[Length];
             int bytesRead = streamResponse.Read(buffer, , Length);
             // write the required bytes
             while (bytesRead > )
             {
                 _stream.Write(buffer, , bytesRead);
                 bytesRead = streamResponse.Read(buffer, , Length);
             }
             return _stream;
         }
         /// <summary>
         /// 为请求准备参数
         /// </summary>
         ///<param name="objhttpItem">参数列表</param>
         /// <param name="_Encoding">读取数据时的编码方式</param>
         private void SetRequest(HttpItem objhttpItem)
         {
             // 验证证书
             SetCer(objhttpItem);
             //设置Header参数
             if (objhttpItem.Header != null && objhttpItem.Header.Count > )
             {
                 foreach (string item in objhttpItem.Header.AllKeys)
                 {
                     request.Headers.Add(item, objhttpItem.Header[item]);
                 }
             }
             // 设置代理
             SetProxy(objhttpItem);
             //请求方式Get或者Post
             request.Method = objhttpItem.Method;
             request.Timeout = objhttpItem.Timeout;
             request.ReadWriteTimeout = objhttpItem.ReadWriteTimeout;
             //Accept
             request.Accept = objhttpItem.Accept;
             //ContentType返回类型
             request.ContentType = objhttpItem.ContentType;
             //UserAgent客户端的访问类型，包括浏览器版本和操作系统信息
             request.UserAgent = objhttpItem.UserAgent;
             // 编码
             encoding = objhttpItem.Encoding;
             //设置Cookie
             SetCookie(objhttpItem);
             //来源地址
             request.Referer = objhttpItem.Referer;
             //是否执行跳转功能
             request.AllowAutoRedirect = objhttpItem.Allowautoredirect;
             //设置Post数据
             SetPostData(objhttpItem);
             //设置最大连接
             if (objhttpItem.Connectionlimit > )
                 request.ServicePoint.ConnectionLimit = objhttpItem.Connectionlimit;
         }
         /// <summary>
         /// 设置证书
         /// </summary>
         /// <param name="objhttpItem"></param>
         private void SetCer(HttpItem objhttpItem)
         {
             if (!string.IsNullOrEmpty(objhttpItem.CerPath))
             {
                 //这一句一定要写在创建连接的前面。使用回调的方法进行证书验证。
                 ServicePointManager.ServerCertificateValidationCallback = new System.Net.Security.RemoteCertificateValidationCallback(CheckValidationResult);
                 //初始化对像，并设置请求的URL地址
                 request = (HttpWebRequest)WebRequest.Create(objhttpItem.URL);
                 //将证书添加到请求里
                 request.ClientCertificates.Add(new X509Certificate(objhttpItem.CerPath));
             }
             else
                 //初始化对像，并设置请求的URL地址
                 request = (HttpWebRequest)WebRequest.Create(objhttpItem.URL);
         }
         /// <summary>
         /// 设置Cookie
         /// </summary>
         /// <param name="objhttpItem">Http参数</param>
         private void SetCookie(HttpItem objhttpItem)
         {
             if (!string.IsNullOrEmpty(objhttpItem.Cookie))
                 //Cookie
                 request.Headers[HttpRequestHeader.Cookie] = objhttpItem.Cookie;
             //设置Cookie
             if (objhttpItem.CookieCollection != null)
             {
                 request.CookieContainer = new CookieContainer();
                 request.CookieContainer.Add(objhttpItem.CookieCollection);
             }
         }
         /// <summary>
         /// 设置Post数据
         /// </summary>
         /// <param name="objhttpItem">Http参数</param>
         private void SetPostData(HttpItem objhttpItem)
         {
             //验证在得到结果时是否有传入数据
             if (request.Method.Trim().ToLower().Contains("post"))
             {
                 byte[] buffer = null;
                 //写入Byte类型
                 if (objhttpItem.PostDataType == PostDataType.Byte && objhttpItem.PostdataByte != null && objhttpItem.PostdataByte.Length > )
                 {
                     //验证在得到结果时是否有传入数据
                     buffer = objhttpItem.PostdataByte;
                 }//写入文件
                 else if (objhttpItem.PostDataType == PostDataType.FilePath && !string.IsNullOrEmpty(objhttpItem.Postdata))
                 {
                     StreamReader r = new StreamReader(objhttpItem.Postdata, encoding);
                     buffer = Encoding.Default.GetBytes(r.ReadToEnd());
                     r.Close();
                 } //写入字符串
                 else if (!string.IsNullOrEmpty(objhttpItem.Postdata))
                 {
                     buffer = Encoding.Default.GetBytes(objhttpItem.Postdata);
                 }
                 if (buffer != null)
                 {
                     request.ContentLength = buffer.Length;
                     request.GetRequestStream().Write(buffer, , buffer.Length);
                 }
             }
         }
         /// <summary>
         /// 设置代理
         /// </summary>
         /// <param name="objhttpItem">参数对象</param>
         private void SetProxy(HttpItem objhttpItem)
         {
             if (!string.IsNullOrEmpty(objhttpItem.ProxyIp))
             {
                 //设置代理服务器
                 WebProxy myProxy = new WebProxy(objhttpItem.ProxyIp, false);
                 //建议连接
                 myProxy.Credentials = new NetworkCredential(objhttpItem.ProxyUserName, objhttpItem.ProxyPwd);
                 //给当前请求对象
                 request.Proxy = myProxy;
                 //设置安全凭证
                 request.Credentials = CredentialCache.DefaultNetworkCredentials;
             }
         }
         /// <summary>
         /// 回调验证证书问题
         /// </summary>
         /// <param name="sender">流对象</param>
         /// <param name="certificate">证书</param>
         /// <param name="chain">X509Chain</param>
         /// <param name="errors">SslPolicyErrors</param>
         /// <returns>bool</returns>
         public bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
         {
             // 总是接受
             return true;
         }
         #endregion
         #region 普通类型
         ///<summary>
         ///采用https协议访问网络,根据传入的URl地址，得到响应的数据字符串。
         ///</summary>
         ///<param name="objhttpItem">参数列表</param>
         ///<returns>String类型的数据</returns>
         public HttpResult GetHtml(HttpItem objhttpItem)
         {
             try
             {
                 //准备参数
                 SetRequest(objhttpItem);
             }
             catch (Exception ex)
             {
                 return new HttpResult() { Cookie = "", Header = null, Html = ex.Message, StatusDescription = "配置参考时报错" };
             }
             //调用专门读取数据的类
             return GetHttpRequestData(objhttpItem);
         }
         #endregion
     }
     /// <summary>
     /// Http请求参考类
     /// </summary>
     public class HttpItem
     {
         string _URL = string.Empty;
         /// <summary>
         /// 请求URL必须填写
         /// </summary>
         public string URL
         {
             get { return _URL; }
             set { _URL = value; }
         }
         string _Method = "GET";
         /// <summary>
         /// 请求方式默认为GET方式,当为POST方式时必须设置Postdata的值
         /// </summary>
         public string Method
         {
             get { return _Method; }
             set { _Method = value; }
         }
         int _Timeout = ;
         /// <summary>
         /// 默认请求超时时间
         /// </summary>
         public int Timeout
         {
             get { return _Timeout; }
             set { _Timeout = value; }
         }
         int _ReadWriteTimeout = ;
         /// <summary>
         /// 默认写入Post数据超时间
         /// </summary>
         public int ReadWriteTimeout
         {
             get { return _ReadWriteTimeout; }
             set { _ReadWriteTimeout = value; }
         }
         string _Accept = "text/html, application/xhtml+xml, */*";
         /// <summary>
         /// 请求标头值 默认为text/html, application/xhtml+xml, */*
         /// </summary>
         public string Accept
         {
             get { return _Accept; }
             set { _Accept = value; }
         }
         string _ContentType = "text/html";
         /// <summary>
         /// 请求返回类型默认 text/html
         /// </summary>
         public string ContentType
         {
             get { return _ContentType; }
             set { _ContentType = value; }
         }
         string _UserAgent = "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)";
         /// <summary>
         /// 客户端访问信息默认Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)
         /// </summary>
         public string UserAgent
         {
             get { return _UserAgent; }
             set { _UserAgent = value; }
         }
         Encoding _Encoding = null;
         /// <summary>
         /// 返回数据编码默认为NUll,可以自动识别,一般为utf-8,gbk,gb2312
         /// </summary>
         public Encoding Encoding
         {
             get { return _Encoding; }
             set { _Encoding = value; }
         }
         private PostDataType _PostDataType = PostDataType.String;
         /// <summary>
         /// Post的数据类型
         /// </summary>
         public PostDataType PostDataType
         {
             get { return _PostDataType; }
             set { _PostDataType = value; }
         }
         string _Postdata = string.Empty;
         /// <summary>
         /// Post请求时要发送的字符串Post数据
         /// </summary>
         public string Postdata
         {
             get { return _Postdata; }
             set { _Postdata = value; }
         }
         private byte[] _PostdataByte = null;
         /// <summary>
         /// Post请求时要发送的Byte类型的Post数据
         /// </summary>
         public byte[] PostdataByte
         {
             get { return _PostdataByte; }
             set { _PostdataByte = value; }
         }
         CookieCollection cookiecollection = null;
         /// <summary>
         /// Cookie对象集合
         /// </summary>
         public CookieCollection CookieCollection
         {
             get { return cookiecollection; }
             set { cookiecollection = value; }
         }
         string _Cookie = string.Empty;
         /// <summary>
         /// 请求时的Cookie
         /// </summary>
         public string Cookie
         {
             get { return _Cookie; }
             set { _Cookie = value; }
         }
         string _Referer = string.Empty;
         /// <summary>
         /// 来源地址，上次访问地址
         /// </summary>
         public string Referer
         {
             get { return _Referer; }
             set { _Referer = value; }
         }
         string _CerPath = string.Empty;
         /// <summary>
         /// 证书绝对路径
         /// </summary>
         public string CerPath
         {
             get { return _CerPath; }
             set { _CerPath = value; }
         }
         private Boolean isToLower = false;
         /// <summary>
         /// 是否设置为全文小写，默认为不转化
         /// </summary>
         public Boolean IsToLower
         {
             get { return isToLower; }
             set { isToLower = value; }
         }
         private Boolean allowautoredirect = false;
         /// <summary>
         /// 支持跳转页面，查询结果将是跳转后的页面，默认是不跳转
         /// </summary>
         public Boolean Allowautoredirect
         {
             get { return allowautoredirect; }
             set { allowautoredirect = value; }
         }
         private int connectionlimit = ;
         /// <summary>
         /// 最大连接数
         /// </summary>
         public int Connectionlimit
         {
             get { return connectionlimit; }
             set { connectionlimit = value; }
         }
         private string proxyusername = string.Empty;
         /// <summary>
         /// 代理Proxy 服务器用户名
         /// </summary>
         public string ProxyUserName
         {
             get { return proxyusername; }
             set { proxyusername = value; }
         }
         private string proxypwd = string.Empty;
         /// <summary>
         /// 代理 服务器密码
         /// </summary>
         public string ProxyPwd
         {
             get { return proxypwd; }
             set { proxypwd = value; }
         }
         private string proxyip = string.Empty;
         /// <summary>
         /// 代理 服务IP
         /// </summary>
         public string ProxyIp
         {
             get { return proxyip; }
             set { proxyip = value; }
         }
         private ResultType resulttype = ResultType.String;
         /// <summary>
         /// 设置返回类型String和Byte
         /// </summary>
         public ResultType ResultType
         {
             get { return resulttype; }
             set { resulttype = value; }
         }
         private WebHeaderCollection header = new WebHeaderCollection();
         //header对象
         public WebHeaderCollection Header
         {
             get { return header; }
             set { header = value; }
         }
     }
     /// <summary>
     /// Http返回参数类
     /// </summary>
     public class HttpResult
     {
         string _Cookie = string.Empty;
         /// <summary>
         /// Http请求返回的Cookie
         /// </summary>
         public string Cookie
         {
             get { return _Cookie; }
             set { _Cookie = value; }
         }
         CookieCollection cookiecollection = new CookieCollection();
         /// <summary>
         /// Cookie对象集合
         /// </summary>
         public CookieCollection CookieCollection
         {
             get { return cookiecollection; }
             set { cookiecollection = value; }
         }
         private string html = string.Empty;
         /// <summary>
         /// 返回的String类型数据 只有ResultType.String时才返回数据，其它情况为空
         /// </summary>
         public string Html
         {
             get { return html; }
             set { html = value; }
         }
         private byte[] resultbyte = null;
         /// <summary>
         /// 返回的Byte数组 只有ResultType.Byte时才返回数据，其它情况为空
         /// </summary>
         public byte[] ResultByte
         {
             get { return resultbyte; }
             set { resultbyte = value; }
         }
         private WebHeaderCollection header = new WebHeaderCollection();
         //header对象
         public WebHeaderCollection Header
         {
             get { return header; }
             set { header = value; }
         }
         private string statusDescription = "";
         /// <summary>
         /// 返回状态说明
         /// </summary>
         public string StatusDescription
         {
             get { return statusDescription; }
             set { statusDescription = value; }
         }
         private HttpStatusCode statusCode = HttpStatusCode.OK;
         /// <summary>
         /// 返回状态码,默认为OK
         /// </summary>
         public HttpStatusCode StatusCode
         {
             get { return statusCode; }
             set { statusCode = value; }
         }
     }
     /// <summary>
     /// 返回类型
     /// </summary>
     public enum ResultType
     {
         /// <summary>
         /// 表示只返回字符串 只有Html有数据
         /// </summary>
         String,
         /// <summary>
         /// 表示返回字符串和字节流 ResultByte和Html都有数据返回
         /// </summary>
         Byte
     }
     /// <summary>
     /// Post的数据格式默认为string
     /// </summary>
     public enum PostDataType
     {
         /// <summary>
         /// 字符串类型，这时编码Encoding可不设置
         /// </summary>
         String,
         /// <summary>
         /// Byte类型，需要设置PostdataByte参数的值编码Encoding可设置为空
         /// </summary>
         Byte,
         /// <summary>
         /// 传文件，Postdata必须设置为文件的绝对路径，必须设置Encoding的值
         /// </summary>
         FilePath
     }
 }