根据URL提取页面的Title，根据网页的charset自动判断Encoding

using System;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;

internal class Program
{
    // 获取网页的HTML内容，根据网页的charset自动判断Encoding
    public static string GetHtml(string url)
    {
        return GetHtml(url, null);
    }

    // 获取网页的HTML内容，指定Encoding
    private static string GetHtml(string url, Encoding encoding)
    {
        byte[] buf = new WebClient().DownloadData(url);
        if (encoding != null) return encoding.GetString(buf);
        string html = Encoding.UTF8.GetString(buf);
        encoding = GetEncoding(html);
        if (encoding == null || encoding == Encoding.UTF8) return html;
        return encoding.GetString(buf);
    }

    // 根据网页的HTML内容提取网页的Encoding
    private static Encoding GetEncoding(string html)
    {
        string pattern = @"(?i)\bcharset=(?<charset>[-a-zA-Z_0-9]+)";
        string charset = Regex.Match(html, pattern).Groups["charset"].Value;
        try
        {
            return Encoding.GetEncoding(charset);
        }
        catch (ArgumentException)
        {
            return null;
        }
    }

    // 根据网页的HTML内容提取网页的Title
    private static string GetTitle(string html)
    {
        string pattern = @"(?si)<title(?:\s+(?:""[^""]*""|'[^']*'|[^""'>])*)?>(?<title>.*?)</title>";
        return Regex.Match(html, pattern).Groups["title"].Value.Trim();
    }

    // 打印网页的Encoding和Title
    private static void PrintEncodingAndTitle(string url)
    {
        string html = GetHtml(url);
        Console.WriteLine("[{0}] [{1}]", GetEncoding(html), GetTitle(html));
    }

    // 程序入口
    private static void Main()
    {
        PrintEncodingAndTitle("http://www.msdn.net/");
        PrintEncodingAndTitle("http://www.cnblogs.com/");
        PrintEncodingAndTitle("http://www.cnblogs.com/skyiv/");
        PrintEncodingAndTitle("http://www.csdn.net/");
        PrintEncodingAndTitle("http://news.163.com/");
    }
}

/* 程序输出：
[] [MSDN: Microsoft Developer Network]
[System.Text.UTF8Encoding] [博客园 - 程序员的网上家园]
[System.Text.UTF8Encoding] [空间/IV - 博客园]
[System.Text.UTF8Encoding] [CSDN.NET - 中国最大的IT技术社区，为IT专业技术人员提供最全面的信息传播和服务平台]
[System.Text.DBCSCodePageEncoding] [新闻中心_网易新闻]

*/