WebClient位于System.Net命名空间下，通过这个类可以方便的创建Http请求并获取返回内容。

using  System;
using  System.Collections.Generic;
using  System.Text;
using  System.Net;
using  System.IO;

namespace  ConsoleWebClient
{
     class  Program
    {
         static   void  Main( string [] args)
        {
             string  uri  =   " http://www.cnblogs.com " ;
            WebClient wc  =   new  WebClient();
            Stream st  =  wc.OpenRead(uri);
            StreamReader sr  =   new  StreamReader(st);
             string  res  =  sr.ReadToEnd();
            sr.Close();
            st.Close();
            Console.WriteLine(res);
            Console.ReadKey();
        }

         public   void  ReadPageContent()
        {
             string  uri  =   " http://www.cnblogs.com " ;
            WebClient wc  =   new  WebClient();
             byte [] bResponse  =  wc.DownloadData(uri);
             string  strResponse  =  Encoding.UTF8.GetString(bResponse);
            Console.WriteLine(strResponse);
            Console.ReadKey();
        }
    }
}