這個需求來自于我最近練手的一個項目，在項目中我需要將一些自己發(fā)表的和收藏整理的網文集中到一個地方存放，如果全部采用手工操作工作量大而且繁瑣，因此周公決定利用C#來實現(xiàn)。在很多地方都需要驗證用戶身份才可以進行下一步操作，這就免不了POST請求來登錄，在實際過程中發(fā)現(xiàn)有些網站登錄是HTTPS形式的，在解決過程中遇到了一些小問題，現(xiàn)在跟大家分享。

　　通用輔助類

　　下面是我編寫的一個輔助類，在這個類中采用了HttpWebRequest中發(fā)送GET/HTTP/HTTPS請求，因為有的時候需要獲取認證信息（如Cookie），所以返回的是HttpWebResponse對象，有了返回的HttpWebResponse實例，可以獲取登錄過程中返回的會話信息，也可以獲取響應流。
代碼如下：

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;
/*
* 作者：周公(zhoufoxcn)
* 日期：2011-05-08
* 原文出處：//blog.csdn.net/zhoufoxcn 或//zhoufoxcn.blog.51cto.com
* 版權說明：本文可以在保留原文出處的情況下使用于非商業(yè)用途，周公對此不作任何擔保或承諾。
* */
namespace BaiduCang
{
/// <summary>
/// 有關HTTP請求的輔助類
/// </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>
/// 創(chuàng)建GET方式的HTTP請求
/// </summary>
/// <param name="url">請求的URL</param>
/// <param name="timeout">請求的超時時間</param>
/// <param name="userAgent">請求的客戶端瀏覽器信息，可以為空</param>
/// <param name="cookies">隨同HTTP請求發(fā)送的Cookie信息，如果不需要身份驗證可以為空</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>
/// 創(chuàng)建POST方式的HTTP請求
/// </summary>
/// <param name="url">請求的URL</param>
/// <param name="parameters">隨同請求POST的參數(shù)名稱及參數(shù)值字典</param>
/// <param name="timeout">請求的超時時間</param>
/// <param name="userAgent">請求的客戶端瀏覽器信息，可以為空</param>
/// <param name="requestEncoding">發(fā)送HTTP請求時所用的編碼</param>
/// <param name="cookies">隨同HTTP請求發(fā)送的Cookie信息，如果不需要身份驗證可以為空</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;
//如果是發(fā)送HTTPS請求
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數(shù)據
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; //總是接受
}
}
}
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;
/*
* 作者：周公(zhoufoxcn)
* 日期：2011-05-08
* 原文出處：//blog.csdn.net/zhoufoxcn 或//zhoufoxcn.blog.51cto.com
* 版權說明：本文可以在保留原文出處的情況下使用于非商業(yè)用途，周公對此不作任何擔保或承諾。
* */
namespace BaiduCang
{
/// <summary>
/// 有關HTTP請求的輔助類
/// </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>
/// 創(chuàng)建GET方式的HTTP請求
/// </summary>
/// <param name="url">請求的URL</param>
/// <param name="timeout">請求的超時時間</param>
/// <param name="userAgent">請求的客戶端瀏覽器信息，可以為空</param>
/// <param name="cookies">隨同HTTP請求發(fā)送的Cookie信息，如果不需要身份驗證可以為空</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>
/// 創(chuàng)建POST方式的HTTP請求
/// </summary>
/// <param name="url">請求的URL</param>
/// <param name="parameters">隨同請求POST的參數(shù)名稱及參數(shù)值字典</param>
/// <param name="timeout">請求的超時時間</param>
/// <param name="userAgent">請求的客戶端瀏覽器信息，可以為空</param>
/// <param name="requestEncoding">發(fā)送HTTP請求時所用的編碼</param>
/// <param name="cookies">隨同HTTP請求發(fā)送的Cookie信息，如果不需要身份驗證可以為空</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;
//如果是發(fā)送HTTPS請求
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數(shù)據
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; //總是接受
}
}
}

　　從上面的代碼中可以看出POST數(shù)據到HTTP和HTTPS站點不同，POST數(shù)據到HTTPS站點的時候需要設置ServicePointManager類的ServerCertificateValidationCallback屬性，并且在POST到//passport.baidu.com/?login時還需要將HttpWebResquest實例的ProtocolVersion屬性設置為HttpVersion.Version10（這個未驗證是否所有的HTTPS站點都需要設置），否則在調用GetResponse()方法時會拋出“基礎連接已經關閉: 連接被意外關閉。”的異常。

用法舉例

　　這個類用起來也很簡單：

　　（1）POST數(shù)據到HTTPS站點，用它來登錄百度：

string loginUrl = "//passport.baidu.com/?login";
string userName = "userName";
string password = "password";
string tagUrl = "//cang.baidu.com/"+userName+"/tags";
Encoding encoding = Encoding.GetEncoding("gb2312");

IDictionary<string, string> parameters = new Dictionary<string, string>();
parameters.Add("tpl", "fa");
parameters.Add("tpl_reg", "fa");
parameters.Add("u", tagUrl);
parameters.Add("psp_tt", "0");
parameters.Add("username", userName);
parameters.Add("password", password);
parameters.Add("mem_pass", "1");
HttpWebResponse response = HttpWebResponseUtility.CreatePostHttpResponse(loginUrl, parameters, null, null, encoding, null);
string cookieString = response.Headers["Set-Cookie"];
string loginUrl = "//passport.baidu.com/?login";
string userName = "userName";
string password = "password";
string tagUrl = "//cang.baidu.com/"+userName+"/tags";
Encoding encoding = Encoding.GetEncoding("gb2312");

IDictionary<string, string> parameters = new Dictionary<string, string>();
parameters.Add("tpl", "fa");
parameters.Add("tpl_reg", "fa");
parameters.Add("u", tagUrl);
parameters.Add("psp_tt", "0");
parameters.Add("username", userName);
parameters.Add("password", password);
parameters.Add("mem_pass", "1");
HttpWebResponse response = HttpWebResponseUtility.CreatePostHttpResponse(loginUrl, parameters, null, null, encoding, null);
string cookieString = response.Headers["Set-Cookie"];

　　（2）發(fā)送GET請求到HTTP站點

　　在cookieString中包含了服務器端返回的會話信息數(shù)據，從中提取了之后可以設置Cookie下次登錄時帶上這個Cookie就可以以認證用戶的信息，假設我們已經登錄成功并且獲取了Cookie，那么發(fā)送GET請求的代碼如下：

string userName = "userName";
string tagUrl = "//cang.baidu.com/"+userName+"/tags";
CookieCollection cookies = new CookieCollection();//如何從response.Headers["Set-Cookie"];中獲取并設置CookieCollection的代碼略
response = HttpWebResponseUtility.CreateGetHttpResponse(tagUrl, null, null, cookies);
string userName = "userName";
string tagUrl = "//cang.baidu.com/"+userName+"/tags";
CookieCollection cookies = new CookieCollection();//如何從response.Headers["Set-Cookie"];中獲取并設置CookieCollection的代碼略
response = HttpWebResponseUtility.CreateGetHttpResponse(tagUrl, null, null, cookies);

　　(3)發(fā)送POST請求到HTTP站點

　　以登錄51CTO為例

string loginUrl = "//home.51cto.com/index.php?s=/Index/doLogin";
string userName = "userName";
string password = "password";

IDictionary<string, string> parameters = new Dictionary<string, string>();
parameters.Add("email", userName);
parameters.Add("passwd", password);

HttpWebResponse response = HttpWebResponseUtility.CreatePostHttpResponse(loginUrl, parameters, null, null, Encoding.UTF8, null);
string loginUrl = "//home.51cto.com/index.php?s=/Index/doLogin";
string userName = "userName";
string password = "password";

IDictionary<string, string> parameters = new Dictionary<string, string>();
parameters.Add("email", userName);
parameters.Add("passwd", password);

HttpWebResponse response = HttpWebResponseUtility.CreatePostHttpResponse(loginUrl, parameters, null, null, Encoding.UTF8, null);

　　在這里說句題外話，CSDN的登錄處理是由//passport.csdn.net/ajax/accounthandler.ashx這個Handler來處理的。

總結

　　在本文只是講解了在C#中發(fā)送請求到HTTP和HTTPS的用法，分GET/POST兩種方式，為減少一些繁瑣和機械的編碼，周公將其封裝為一個類，發(fā)送數(shù)據之后返回HttpWebResponse對象實例，利用這個實例我們可以獲取服務器端返回的Cookie以便用認證用戶的身份繼續(xù)發(fā)送請求，或者讀取服務器端響應的內容，不過在讀取響應內容時要注意響應格式和編碼，本來在這個類中還有讀取HTML和WML內容的方法（包括服務器使用壓縮方式傳輸?shù)臄?shù)據），但限于篇幅和其它方面的原因，此處省略掉了。