asp.net c#采集需要登录页面的实现原理及代码

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首先说明：代码片段是从网络获取，然后自己修改。我想好的东西应该拿来分享。

实现原理：当我们采集页面的时候，如果被采集的网站需要登录才能采集。不管是基于Cookie还是基于Session，我们都会首先发送一个Http请求头，这个Http请求头里面就包含了网站需要的Cookie信息。当网站接收到发送过来的Http请求头时，会从Http请求头获取相关的Cookie或者Session信息，然后由程序来处理，决定你是否有权限访问当前页面。

好了，原理搞清楚了，就好办了。我们所要做的仅仅是在采集的时候（或者说HttpWebRequest提交数据的时候），将Cookie信息放入Http请求头里面就可以了。

在这里我提供2种方法。
第一种，直接将Cookie信息放入HttpWebRequest的CookieContainer里。看代码：

复制代码代码如下:

 
protected void Page_Load(object sender, EventArgs e) 
{ 
//设置Cookie，存入Hashtable 
Hashtable ht = new Hashtable(); 
ht.Add("username", "youraccount"); 
ht.Add("id", "yourid"); 
this.Collect(ht); 
} 
public void Collect(Hashtable ht) 
{ 
string content = string.Empty; 
string url = "http://www.ibest100.com/需要登录后才能采集的页面"; 
string host = "http://www.ibest100.com"; 
try 
{ 
//获取提交的字节 
byte[] bs = Encoding.UTF8.GetBytes(content); 
//设置提交的相关参数 
HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(url); 
req.Method = "POST"; 
req.ContentType = "application/json;charset=utf-8"; 
req.ContentLength = bs.Length; 
//将Cookie放入CookieContainer，然后再将CookieContainer添加到HttpWebRequest 
CookieContainer cc = new CookieContainer(); 
cc.Add(new Uri(host), new Cookie("username", ht["username"].ToString())); 
cc.Add(new Uri(host), new Cookie("id", ht["id"].ToString())); 
req.CookieContainer = cc; 
//提交请求数据 
Stream reqStream = req.GetRequestStream(); 
reqStream.Write(bs, 0, bs.Length); 
reqStream.Close(); 
//接收返回的页面，必须的，不能省略 
WebResponse wr = req.GetResponse(); 
System.IO.Stream respStream = wr.GetResponseStream(); 
System.IO.StreamReader reader = new System.IO.StreamReader(respStream, System.Text.Encoding.GetEncoding("utf-8")); 
string t = reader.ReadToEnd(); 
System.Web.HttpContext.Current.Response.Write(t); 
wr.Close(); 
} 
catch (Exception ex) 
{ 
System.Web.HttpContext.Current.Response.Write("异常在getPostRespone:" + ex.Source + ":" + ex.Message); 
} 
} 

第二种，每次打开采集程序时，需要先到被采集的网站模拟登录一次，获取CookieContainer，然后再采集。看代码：

复制代码代码如下:

 
protected void Page_Load(object sender, EventArgs e) 
{ 
try 
{ 
CookieContainer cookieContainer = new CookieContainer(); 
string formatString = "username={0}&password={1}";//*************** 
string postString = string.Format(formatString, "youradminaccount", "yourpassword"); 
//将提交的字符串数据转换成字节数组 
byte[] postData = Encoding.UTF8.GetBytes(postString); 
//设置提交的相关参数 
string URI = "http://www.ibest100.com/登录页面";//*************** 
HttpWebRequest request = WebRequest.Create(URI) as HttpWebRequest; 
request.Method = "POST"; 
request.KeepAlive = false; 
request.ContentType = "application/x-www-form-urlencoded"; 
request.CookieContainer = cookieContainer; 
request.ContentLength = postData.Length; 
// 提交请求数据 
System.IO.Stream outputStream = request.GetRequestStream(); 
outputStream.Write(postData, 0, postData.Length); 
outputStream.Close(); 
//接收返回的页面，必须的，不能省略 
HttpWebResponse response = request.GetResponse() as HttpWebResponse; 
System.IO.Stream responseStream = response.GetResponseStream(); 
System.IO.StreamReader reader = new System.IO.StreamReader(responseStream, Encoding.GetEncoding("gb2312")); 
string srcString = reader.ReadToEnd(); 
//打开您要访问的页面 
URI = "http://www.ibest100.com/需要登录后才能采集的页面";//*************** 
request = WebRequest.Create(URI) as HttpWebRequest; 
request.Method = "GET"; 
request.KeepAlive = false; 
request.CookieContainer = cookieContainer; 
// 接收返回的页面 
response = request.GetResponse() as HttpWebResponse; 
responseStream = response.GetResponseStream(); 
reader = new System.IO.StreamReader(responseStream, Encoding.GetEncoding("gb2312")); 
srcString = reader.ReadToEnd(); 
//输出获取的页面或者处理 
Response.Write(srcString); 
} 
catch (WebException we) 
{ 
string msg = we.Message; 
Response.Write(msg); 
} 
} 