C# Http请求（GET/HTTP/HTTPS）

using System;  
using System.Collections.Generic;  
using System.Linq;  
using System.Text;  
using System.Net.Security;  
using System.Security.Cryptography.X509Certificates;  
using System.DirectoryServices.Protocols;  
using System.ServiceModel.Security;  
using System.Net;  
using System.IO;  
using System.IO.Compression;  
using System.Text.RegularExpressions;  

namespace BaiduCang  
{  
   /// <summary>  
   /// 有关HTTP请求的辅助类  
   /// </summary>  
   public class HttpWebResponseUtility  
   {  
       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)";  
       /// <summary>  
       /// 创建GET方式的HTTP请求  
       /// </summary>  
       /// <param name="url">请求的URL</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="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 CreateGetHttpResponse(string url,int? timeout, string userAgent,CookieCollection cookies)  
       {  
           if (string.IsNullOrEmpty(url))  
           {  
               throw new ArgumentNullException("url");  
           }  
           HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;  
           request.Method = "GET";  
           request.UserAgent = DefaultUserAgent;  
           if (!string.IsNullOrEmpty(userAgent))  
           {  
               request.UserAgent = userAgent;  
           }  
           if (timeout.HasValue)  
           {  
               request.Timeout = timeout.Value;  
           }  
           if (cookies != null)  
           {  
               request.CookieContainer = new CookieContainer();  
               request.CookieContainer.Add(cookies);  
           }  
           return request.GetResponse() as HttpWebResponse;  
       }  
       /// <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 
           {  
               request = WebRequest.Create(url) as HttpWebRequest;  
           }  
           request.Method = "POST";  
           request.ContentType = "application/x-www-form-urlencoded";  
             
           if (!string.IsNullOrEmpty(userAgent))  
           {  
               request.UserAgent = userAgent;  
           }  
           else 
           {  
               request.UserAgent = DefaultUserAgent;  
           }  

           if (timeout.HasValue)  
           {  
               request.Timeout = timeout.Value;  
           }  
           if (cookies != null)  
           {  
               request.CookieContainer = new CookieContainer();  
               request.CookieContainer.Add(cookies);  
           }  
           //如果需要POST数据  
           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  
       }  
   }  
}