using System;using System.Xml;using System.Text;using System.Net;using System.IO;using System.Collections;using System.Text.RegularExpressions;public class App{    public static void Main()    {        string strCode;        ArrayList alLinks;         Console.Write("请输入一个网页地址：");        string strURL = Console.ReadLine();        if (strURL.Substring(0, 7) != @"http://")        {            strURL = @"http://" + strURL;        }         Console.WriteLine("正在获取页面代码，请稍侯...");        strCode = GetPageSource(strURL);        Console.WriteLine("正在提取超链接，请稍侯...");        alLinks = GetHyperLinks(strCode);        Console.WriteLine("正在写入文件，请稍侯...");        WriteToXml(strURL, alLinks);    }    // 获取指定网页的HTML代码     static string GetPageSource(string URL)    {        Uri uri = new Uri(URL);         HttpWebRequest hwReq = (HttpWebRequest)WebRequest.Create(uri);        HttpWebResponse hwRes = (HttpWebResponse)hwReq.GetResponse();         hwReq.Method = "Get";         hwReq.KeepAlive = false;         StreamReader reader = new StreamReader(hwRes.GetResponseStream(), System.Text.Encoding.GetEncoding("GB2312"));         return reader.ReadToEnd();    }    // 提取HTML代码中的网址     static ArrayList GetHyperLinks(string htmlCode)    {        ArrayList al = new ArrayList();         string strRegex = @"http://([\w-]+\.)+[\w-]+(/[\w- ./?%&=]*)?";         Regex r = new Regex(strRegex, RegexOptions.IgnoreCase);        MatchCollection m = r.Matches(htmlCode);         for (int i = 0; i <= m.Count - 1; i++)        {            bool rep = false;            string strNew = m[i].ToString();            // 过滤重复的URL             foreach (string str in al)            {                if (strNew == str)                {                    rep = true;                    break;                }            }             if (!rep) al.Add(strNew);        }         al.Sort();         return al;    }    // 把网址写入xml文件     static void WriteToXml(string strURL, ArrayList alHyperLinks)    {        XmlTextWriter writer = new XmlTextWriter("HyperLinks.xml", Encoding.UTF8);         writer.Formatting = Formatting.Indented;        writer.WriteStartDocument(false);        writer.WriteDocType("HyperLinks", null, "urls.dtd", null);        writer.WriteComment("提取自" + strURL + "的超链接");        writer.WriteStartElement("HyperLinks");        writer.WriteStartElement("HyperLinks", null);        writer.WriteAttributeString("DateTime", DateTime.Now.ToString());         foreach (string str in alHyperLinks)        {            string title = GetDomain(str);            string body = str;            writer.WriteElementString(title, null, body);        }         writer.WriteEndElement();        writer.WriteEndElement();         writer.Flush();        writer.Close();    }    // 获取网址的域名后缀     static string GetDomain(string strURL)    {        string retVal;         string strRegex = @"(\.com/|\.net/|\.cn/|\.org/|\.gov/)";         Regex r = new Regex(strRegex, RegexOptions.IgnoreCase);        Match m = r.Match(strURL);        retVal = m.ToString();         strRegex = @"\.|/{1}quot;;        retVal = Regex.Replace(retVal, strRegex, "").ToString();         if (retVal == "")            retVal = "other";         return retVal;    }}