StreamReader read txt file from a http link

using System;
using System.IO;
using System.Net;

WebRequest request = WebRequest.Create(url);
request.Credentials = new NetworkCredential("username", "password");
//if there is credential.
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
using (StreamReader sr
= new StreamReader(response.GetResponseStream()))
{
string tstr = sr.ReadToEnd();
......
}