.Net中抓取网页内容

public static string getPage(String url)
  {
   WebResponse result = null;
   System.Text.StringBuilder txthtml=new StringBuilder();
   try
   { 
    WebRequest req = WebRequest.Create(url);
    result = req.GetResponse();
    Stream ReceiveStream = result.GetResponseStream();
    Encoding encode = System.Text.Encoding.GetEncoding("gb2312");
    StreamReader sr = new StreamReader(ReceiveStream,encode);

    if (true)
    {
     Char[] read = new Char[256];
     int count = sr.Read( read, 0, 256 );

     // this.Message.Text+="HTML.../r/n";
     while (count > 0)
     {
      String str = new String(read, 0, count);
      txthtml.Append(str);
      count = sr.Read(read, 0, 256);
     }
  
    }
   }
   catch(Exception ex)
   {
    txthtml.Append("err:" + ex.Message + url);

   }
   finally
   {
    if (result != null)
    {
     result.Close();
    }
    
   }

   return txthtml.ToString();
  }