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，则能实现SESSION的还原。见getPage方法 源程式如下： getHttpInfo.aspx:

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 description for WebForm1. ///

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 0) { String str = new String(read, 0, count); strResult += str; count = sr.Read(read, 0, 256); } } catch(Exception e) { strResult = e.ToString(); } finally { if ( res != null ) { res.Close(); } } return strResult; } public static string getPage(String url, String paramList) { HttpWebResponse res = null; string strResult = ""; try { HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url); req.Method = "POST"; req.KeepAlive = true; req.ContentType = "application/x-www-form-urlencoded"; CookieContainer cookieCon = new CookieContainer(); req.CookieContainer = cookieCon; req.CookieContainer.SetCookies(new Uri(url),cookieheader); StringBuilder UrlEncoded = new StringBuilder(); Char[] reserved = {?, =, &}; byte[] SomeBytes = null; if (paramList != null) { int i=0, j; while(i 0) { String str = new String(read, 0, count); strResult += str; count = sr.Read(read, 0, 256); } } catch(Exception e) { strResult = e.ToString(); } finally { if ( res != null ) { res.Close(); } } return strResult; } #region Web Form Designer generated code override protected void OnInit(EventArgs e) { // // CODEGEN: This call is required by the ASP.NET Web Form Designer. // InitializeComponent(); base.OnInit(e); } ///

/// Required method for Designer support - do not modify /// the contents of this method with the code editor. ///

private void InitializeComponent() { this.Load += new System.EventHandler(this.Page_Load); } #endregion } }