asp.net 抓取网页源码三种实现方法

/// <summary>  

        /// 用HttpWebRequest取得网页源码  
        /// 对于带BOM的网页很有效，不管是什么编码都能正确识别  
        /// </summary>  
        /// <param name="url">网页地址" </param>   
        /// <returns>返回网页源文件</returns>  
        public static string GetHtmlSource2(string  url)
        {
            //处理内容  
            string html = "";
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            request.Accept = "*/*"; //接受任意文件
            request.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.1.4322)"; // 模拟使用IE在浏览 http://www.52mvc.com
            request.AllowAutoRedirect = true;//是否允许302
            //request.CookieContainer = new CookieContainer();//cookie容器，
            request.Referer = url; //当前页面的引用

 
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            Stream stream = response.GetResponseStream();
            StreamReader reader = new StreamReader(stream, Encoding.Default);
            html = reader.ReadToEnd();
            stream.Close();

 
            return html;
        }
 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.IO;
using System.Text;
using System.Net;

namespace MySql
{
    public class GetHttpData
    {
        public static string GetHttpData2(string Url)
        {
            string sException = null;
            string sRslt = null;
            WebResponse oWebRps = null;
            WebRequest oWebRqst = WebRequest.Create(Url);
            oWebRqst.Timeout = 50000;
            try
            {

                oWebRps = oWebRqst.GetResponse();

            }
            catch (WebException e)
            {
                sException = e.Message.ToString();
            }
            catch (Exception e)
            {
                sException = e.ToString();

            }
            finally
            {
                if (oWebRps != null)
                {

                    StreamReader oStreamRd = new StreamReader(oWebRps.GetResponseStream(), Encoding.GetEncoding("utf-8"));
                    sRslt = oStreamRd.ReadToEnd();
                    oStreamRd.Close();
                    oWebRps.Close();
                }
            }

            return sRslt;
        }

    }
}

    public static string getHtml(string url, params  string [] charSets)//url是要访问的网站地址，charSet是目标网页的编码，如果传入的是null或者""，那就自动分析网页的编码
    {
        try
        {
            string charSet = null;
            if (charSets.Length == 1) {
                charSet = charSets[0];
            }
            WebClient myWebClient = new WebClient(); //创建WebClient实例myWebClient
            // 需要注意的：
            //有的网页可能下不下来，有种种原因比如需要cookie,编码问题等等
            //这是就要具体问题具体分析比如在头部加入cookie
            // webclient.Headers.Add("Cookie", cookie);
            //这样可能需要一些重载方法。根据需要写就可以了

 
            //获取或设置用于对向 Internet 资源的请求进行身份验证的网络凭据。
            myWebClient.Credentials = CredentialCache.DefaultCredentials;
            //如果服务器要验证用户名,密码
            //NetworkCredential mycred = new NetworkCredential(struser, strpassword);
            //myWebClient.Credentials = mycred;
            //从资源下载数据并返回字节数组。（加@是因为网址中间有"/"符号）
            byte[] myDataBuffer = myWebClient.DownloadData(url);
            string strWebData = Encoding.Default.GetString(myDataBuffer);

 
            //获取网页字符编码描述信息
            Match charSetMatch = Regex.Match(strWebData, "<meta([^<]*)charset=([^<]*)\"", RegexOptions.IgnoreCase | RegexOptions.Multiline);
            string webCharSet = charSetMatch.Groups[2].Value;
            if (charSet == null || charSet == "")
                charSet = webCharSet;

 
            if (charSet != null && charSet != "" && Encoding.GetEncoding(charSet) != Encoding.Default)
            {
                strWebData = Encoding.GetEncoding(charSet).GetString(myDataBuffer);
            }
            else {
                strWebData = Encoding.GetEncoding("utf-8").GetString(myDataBuffer);
            }
            return strWebData;
        }
        catch (Exception e) { return ""; }
    }