ASP.NET 抓取网页

protected void GetHtml(string url,int pageSize)
{
int pagesize = Convert.ToInt32(txtPageSize.Text.Trim());//获取到总共有多少页
WebClient wc = new WebClient();
wc.Encoding = Encoding.Default;
for (int i = 1; i <= pagesize; i++)
{
url = url.Trim() + "?pn=";
if (string.IsNullOrEmpty(url))
{
return;
}
url += i;
string html = wc.DownloadString(url);//获取到当前页的html内容

//MatchCollection mc = Regex.Matches(html, @"\w+((-w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+");
MatchCollection mc = Regex.Matches(html, @"[1-9][0-9]{4,11}@(qq|QQ).com");

StringBuilder sb = new StringBuilder();
foreach (Match m in mc)
{
sb.AppendLine(m.Value + ";");
}                string s = sb.ToString();
//File.AppendAllText(@"h:\1.txt", s, Encoding.Default);

}
}