(转) 在C#用HttpWebRequest中发送GET/HTTP/HTTPS请求
转自:http://blog.csdn.net/zhoufoxcn/article/details/6404236
通用辅助类
下面是我编写的一个辅助类,在这个类中采用了HttpWebRequest中发送GET/HTTP/HTTPS请求,因为有的时候需要获取认证信息(如Cookie),所以返回的是HttpWebResponse对象,有了返回的HttpWebResponse实例,可以获取登录过程中返回的会话信息,也可以获取响应流。
代码如下:
- 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
- * 原文出处:http://blog.csdn.net/zhoufoxcn 或http://zhoufoxcn.blog.51cto.com
- * 版权说明:本文可以在保留原文出处的情况下使用于非商业用途,周公对此不作任何担保或承诺。
- * */
- 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
- }
- }
- }
从上面的代码中可以看出POST数据到HTTP和HTTPS站点不同,POST数据到HTTPS站点的时候需要设置ServicePointManager类的ServerCertificateValidationCallback属性,并且在POST到https://passport.baidu.com/?login时还需要将HttpWebResquest实例的ProtocolVersion属性设置为HttpVersion.Version10(这个未验证是否所有的HTTPS站点都需要设置),否则在调用GetResponse()方法时会抛出“基础连接已经关闭: 连接被意外关闭。”的异常。
用法举例
这个类用起来也很简单:
(1)POST数据到HTTPS站点,用它来登录百度:
- string loginUrl = "https://passport.baidu.com/?login";
- string userName = "userName";
- string password = "password";
- string tagUrl = "http://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)发送GET请求到HTTP站点
在cookieString中包含了服务器端返回的会话信息数据,从中提取了之后可以设置Cookie下次登录时带上这个Cookie就可以以认证用户的信息,假设我们已经登录成功并且获取了Cookie,那么发送GET请求的代码如下:
- string userName = "userName";
- string tagUrl = "http://cang.baidu.com/"+userName+"/tags";
- CookieCollection cookies = new CookieCollection();//如何从response.Headers["Set-Cookie"];中获取并设置CookieCollection的代码略
- response = HttpWebResponseUtility.CreateGetHttpResponse(tagUrl, null, null, cookies);
(3)发送POST请求到HTTP站点
以登录51CTO为例
- string loginUrl = "http://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);
在这里说句题外话,CSDN的登录处理是由http://passport.csdn.net/ajax/accounthandler.ashx这个Handler来处理的。
总结
在本文只是讲解了在C#中发送请求到HTTP和HTTPS的用法,分GET/POST两种方式,为减少一些繁琐和机械的编码,周公将其封装为一个类,发送数据之后返回HttpWebResponse对象实例,利用这个实例我们可以获取服务器端返回的Cookie以便用认证用户的身份继续发送请求,或者读取服务器端响应的内容,不过在读取响应内容时要注意响应格式和编码,本来在这个类中还有读取HTML和WML内容的方法(包括服务器使用压缩方式传输的数据),但限于篇幅和其它方面的原因,此处省略掉了。如有机会,在以后的文章中会继续讲述这方面的内容。