利用HttpRequest 利用HttpRequest登录到某个网站，然后获取网站信息的程式示例 问题：有的网站的相关内容必须要在登录后才能够查看，其登录信息保存在session变量之中。这样，使用asphttp等组件就难以正确得到所要的信息。 解决：使用asp.net中的httprequest和httpresponse来实现。 要点：
1。 通过附加一个cookiecontainer到httprequest对象中，能够得到登录后返回的代表SESSION ID的COOKIE。 见Login方法
2。 将此COOKIE包含在一个cookiecontainer中并附加到另一个HTTPREQUEST请求中，则能够实现SESSION的还原。见getPage方法 源程式如下： getHttpInfo.aspx:
<%@ Page language="c#" Codebehind="getHttpInfo.aspx.cs" AutoEventWireup="false" Inherits="PdfTest.getHttpInfo" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
<title>WebForm1</title>
<meta content="Microsoft Visual Studio 7.0" name="GENERATOR">
<meta content="C#" name="CODE_LANGUAGE">
<meta content="javascript" name="vs_defaultClientscript">
<meta content="http://schemas.microsoft.com/intellisense/ie5"; name="vs_targetSchema">
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
</form>
</body>
</HTML>
getHttpInfo.aspx.cs:
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
//using System.Data.OleDb;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Net;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using Microsoft.Data.Odbc; namespace PdfTest
{
/// <summary>
/// Summary description for WebForm1.
/// </summary>
public class getHttpInfo : System.Web.UI.Page
{
protected static string cookieheader;
private void Page_Load(object sender, System.EventArgs e)
{
// Put user code to initialize the page here string strResult; if (HttpContext.Current.Application["cookieheader"] != null)
{
cookieheader = (string)HttpContext.Current.Application["cookieheader"];
}
else
{
//Login into the website and keep the cookie for the session in the application variable
string strLogin = Login("http://www.thesiteyouwanttovisit/theloginpage.asp";, "Action=&USERID=&Password=") ;
}
strResult = getPage("http://www.thesiteyouwanttovisit/theloginpage.asp";, "Action=&data=") ;
//Write the result to htm file
FileStream htmFile = new FileStream("c:/save.htm", FileMode.OpenOrCreate);
StreamWriter sw = new StreamWriter(htmFile);
sw.Write(strResult);
sw.Close();
htmFile.Close(); // output the result
Response.Write(strResult);
}
public static string Login(String url, String paramList)
{
HttpWebResponse res = null;
string strResult=""; try
{ HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
req.Method = "POST";
req.ContentType = "application/x-www-form-urlencoded";
req.AllowAutoRedirect = false;
CookieContainer cookieCon = new CookieContainer();
req.CookieContainer = cookieCon; StringBuilder UrlEncoded = new StringBuilder();
Char[] reserved = {?, =, &};
byte[] SomeBytes = null; if (paramList != null)
{
int i=0, j;
while(i<paramList.Length)
{
j=paramList.IndexOfAny(reserved, i);
if (j==-1)
{
UrlEncoded.Append(HttpUtility.UrlEncode(paramList.Substring(i, paramList.Length-i)));
break;
}
UrlEncoded.Append(HttpUtility.UrlEncode(paramList.Substring(i, j-i)));
UrlEncoded.Append(paramList.Substring(j,1));
i = j 1;
}
SomeBytes = Encoding.UTF8.GetBytes(UrlEncoded.ToString());
req.ContentLength = SomeBytes.Length;
Stream newStream = req.GetRequestStream();
newStream.Write(SomeBytes, 0, SomeBytes.Length);
newStream.Close();
}
else
{
req.ContentLength = 0;
}
res = (HttpWebResponse)req.GetResponse();
cookieheader = req.CookieContainer.GetCookieHeader(new Uri(url));
HttpContext.Current.Application.Lock();
HttpContext.Current.Application["cookieheader"] = cookieheader;
HttpContext.Current.Application.UnLock(); Stream ReceiveStream = res.GetResponseStream();
Encoding encode = System.Text.Encoding.GetEncoding("utf-8");
StreamReader sr = new StreamReader( ReceiveStream, encode );
Char[] read = new Char[256];
int count = sr.Read( read, 0, 256 );
while (count > 0)
{
String str = new String(read, 0, count);
strResult = str;
count = sr.Read(read, 0, 256);
}
}
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