使用HttpWebRequest和HtmlAgilityPack抓取网页(无乱码)

public string HttpGet(string url)
        {
            string responsestr = "";
            HttpWebRequest req = HttpWebRequest.Create(url) as HttpWebRequest;
            req.Accept = "*/*";
            req.Method = "GET";
            req.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1";
            using (HttpWebResponse response = req.GetResponse() as HttpWebResponse)
            {
                Stream stream;
                if (response.ContentEncoding.ToLower().Contains("gzip"))
                {
                    stream = new GZipStream(response.GetResponseStream(), CompressionMode.Decompress);
                }
                else if (response.ContentEncoding.ToLower().Contains("deflate"))
                {
                    stream = new DeflateStream(response.GetResponseStream(), CompressionMode.Decompress);
                }
                else
                {
                    stream = response.GetResponseStream();
                }
                using (StreamReader reader = new StreamReader(stream, GetEncoding(response.CharacterSet)))
                {
                    responsestr = reader.ReadToEnd();
                    stream.Dispose();
                }
            }
            return responsestr;
        }

public Encoding GetEncoding(string CharacterSet)
        {
            switch (CharacterSet)
            {
                case "gb2312": return Encoding.GetEncoding("gb2312");
                case "utf-8": return Encoding.UTF8;
                default: return Encoding.Default;
            }
        }

调用HttpGet就可以获取网址的源码了，得到源码后， 再用HtmlAgility来解析html了。

string html = HttpGet("http://www.cnblogs.com/");
            HtmlDocument doc = new HtmlDocument();
            doc.LoadHtml(html);
            //获取文章列表
            var artlist = doc.DocumentNode.SelectNodes("//div[@class='post_item']");
            foreach (var item in artlist)
            {
                HtmlDocument adoc = new HtmlDocument();
                adoc.LoadHtml(item.InnerHtml);
                var html_a = adoc.DocumentNode.SelectSingleNode("//a[@class='titlelnk']");
                Response.Write(string.Format("标题为：{0}，链接为：{1}<br>",html_a.InnerText,html_a.Attributes["href"].Value));
            }