网页采集程序

protected void btn_click(object sender, EventArgs e)
{
//方法一：
//System.Net.WebClient wc = new System.Net.WebClient();
//byte[] b = wc.DownloadData("http://www.baidu.com");
//string html = System.Text.Encoding.GetEncoding("gb2312").GetString(b);
//html = html.Substring(html.IndexOf("<p id=\"lg\">") + "<p id=\"lg\">".Length);
//html = html.Substring(0, html.IndexOf("</p>"));
//Response.Write(html);

//方法二：
//获取整个网页
System.Net.WebClient wc = new System.Net.WebClient();
System.IO.Stream sm = wc.OpenRead("http://www.baidu.com");
System.IO.StreamReader sr = new System.IO.StreamReader(sm, System.Text.Encoding.Default, true, 256000);
string html = sr.ReadToEnd();
sr.Close();
//根据规则获取想要的内容
html = html.Substring(html.IndexOf("<p id=\"lg\">") + "<p id=\"lg\">".Length);
html = html.Substring(0, html.IndexOf("</p>"));
Response.Write(html);
}