asp.net c#採集需要登入頁面的實現原理及代碼

首先說明：程式碼片段是從網路擷取，然後自己修改。我想好的東西應該拿來分享。

實現原理：當我們採集頁面的時候，如果被採集的網站需要登入才能採集。不管是基於Cookie還是基於Session，我們都會首先發送一個Http要求標頭，這個Http要求標頭裡面就包含了網站需要的Cookie資訊。當網站接收到發送過來的Http要求標頭時，會從Http要求標頭擷取相關的Cookie或者Session資訊，然後由程式來處理，決定你是否有許可權訪問當前頁面。

好了，原理搞清楚了，就好辦了。我們所要做的僅僅是在採集的時候（或者說HttpWebRequest提交資料的時候），將Cookie資訊放入Http要求標頭裡面就可以了。

在這裡我提供2種方法。
第一種，直接將Cookie資訊放入HttpWebRequest的CookieContainer裡。看代碼： 複製代碼 代碼如下:protected void Page_Load(object sender, EventArgs e)
{
//設定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/需要登入後才能採集的頁面";
string host = "http://www.ibest100.com";
try
{
//擷取提交的位元組
byte[] bs = Encoding.UTF8.GetBytes(content);
//設定提交的相關參數
HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(url);
req.Method = "POST";
req.ContentType = "application/json;charset=utf-8";
req.ContentLength = bs.Length;
//將Cookie放入CookieContainer，然後再將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;
//提交請求資料
Stream reqStream = req.GetRequestStream();
reqStream.Write(bs, 0, bs.Length);
reqStream.Close();
//接收返回的頁面，必須的，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("異常在getPostRespone:" + ex.Source + ":" + ex.Message);
}
}

第二種，每次開啟採集程式時，需要先到被採集的網站類比登入一次，擷取CookieContainer，然後再採集。看代碼： 複製代碼 代碼如下: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");
//將提交的字串資料轉換成位元組數組
byte[] postData = Encoding.UTF8.GetBytes(postString);
//設定提交的相關參數
string URI = "http://www.ibest100.com/登入頁面";//***************
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;
// 提交請求資料
System.IO.Stream outputStream = request.GetRequestStream();
outputStream.Write(postData, 0, postData.Length);
outputStream.Close();
//接收返回的頁面，必須的，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();
//開啟您要訪問的頁面
URI = "http://www.ibest100.com/需要登入後才能採集的頁面";//***************
request = WebRequest.Create(URI) as HttpWebRequest;
request.Method = "GET";
request.KeepAlive = false;
request.CookieContainer = cookieContainer;
// 接收返回的頁面
response = request.GetResponse() as HttpWebResponse;
responseStream = response.GetResponseStream();
reader = new System.IO.StreamReader(responseStream, Encoding.GetEncoding("gb2312"));
srcString = reader.ReadToEnd();
//輸出擷取的頁面或者處理
Response.Write(srcString);
}
catch (WebException we)
{
string msg = we.Message;
Response.Write(msg);
}
}

也許有人會問，如果對方登入的時候要驗證碼怎麼辦？那你就用第一種方式吧，只不過需要你分析對方的Cookie。

應用範圍：採集資料、論壇發帖、部落格發文。