本文實例講述了C#實現抓取和分析網頁類。分享給大家供大家參考。具體分析如下：
這裡介紹了抓取和分析網頁的類。
其主要功能有：
1、提取網頁的純文本，去所有html標簽和javascript代碼
2、提取網頁的鏈接，包括href和frame及iframe
3、提取網頁的title等(其它的標簽可依此類推，正則是一樣的)
4、可以實現簡單的表單提交及cookie保存
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using System.Data; using System.Configuration; using System.Net; using System.IO; using System.Text; using System.Collections.Generic; using System.Text.RegularExpressions; using System.Threading; using System.Web; /// <summary> /// 網頁類 /// </summary> public class WebPage { #region 私有成員 private Uri m_uri; //網址 private List<Link> m_links; //此網頁上的鏈接 private string m_title; //此網頁的標題 private string m_html; //此網頁的HTML代碼 private string m_outstr; //此網頁可輸出的純文本 private bool m_good; //此網頁是否可用 private int m_pagesize; //此網頁的大小 private static Dictionary<string, CookieContainer> webcookies = new Dictionary<string, CookieContainer>();//存放所有網頁的Cookie private string m_post; //此網頁的登陸頁需要的POST數據 private string m_loginurl; //此網頁的登陸頁 #endregion #region 私有方法 /// <summary> /// 這私有方法從網頁的HTML代碼中分析出鏈接信息 /// </summary> /// <returns>List<Link></returns> private List<Link> getLinks() { if (m_links.Count == 0) { Regex[] regex = new Regex[2]; regex[0] = new Regex("(?m)<a[^><]+href=("|')?(?<url>([^>"'s)])+)("|')?[^>]*>(?<text>(w|W)*?)</", RegexOptions.Multiline | RegexOptions.IgnoreCase); regex[1] = new Regex("<[i]*frame[^><]+src=("|')?(?<url>([^>"'s)])+)("|')?[^>]*>", RegexOptions.Multiline | RegexOptions.IgnoreCase); for (int i = 0; i < 2; i++) { Match match = regex[i].Match(m_html); while (match.Success) { try { string url = new Uri(m_uri, match.Groups["url"].Value).AbsoluteUri; string text = ""; if (i == 0) text = new Regex("(<[^>]+>)|(s)|( )|&|"", RegexOptions.Multiline | RegexOptions.IgnoreCase).Replace(match.Groups["text"].Value, ""); Link link = new Link(url, text); m_links.Add(link); } catch(Exception ex){Console.WriteLine(ex.Message); }; match = match.NextMatch(); } } } return m_links; } /// <summary> /// 此私有方法從一段HTML文本中提取出一定字數的純文本 /// </summary> /// <param name="instr">HTML代碼</param> /// <param name="firstN">提取從頭數多少個字</param> /// <param name="withLink">是否要鏈接裡面的字</param> /// <returns>純文本</returns> private string getFirstNchar(string instr, int firstN, bool withLink) { if (m_outstr == "") { m_outstr = instr.Clone() as string; m_outstr = new Regex(@"(?m)<script[^>]*>(w|W)*?</script[^>]*>", RegexOptions.Multiline | RegexOptions.IgnoreCase ).Replace(m_outstr, ""); m_outstr = new Regex(@"(?m)<style[^>]*>(w|W)*?</style[^>]*>", RegexOptions.Multiline | RegexOptions.IgnoreCase ).Replace(m_outstr, ""); m_outstr = new Regex(@"(?m)<select[^>]*>(w|W)*?</select[^>]*>", RegexOptions.Multiline | RegexOptions.IgnoreCase ).Replace(m_outstr, ""); if (!withLink) m_outstr = new Regex(@"(?m)<a[^>]*>(w|W)*?</a[^>]*>", RegexOptions.Multiline | RegexOptions.IgnoreCase).Replace(m_outstr, ""); Regex objReg = new System.Text.RegularExpressions.Regex("(<[^>]+?>)| ", RegexOptions.Multiline | RegexOptions.IgnoreCase); m_outstr = objReg.Replace(m_outstr, ""); Regex objReg2 = new System.Text.RegularExpressions.Regex("(s)+", RegexOptions.Multiline | RegexOptions.IgnoreCase); m_outstr = objReg2.Replace(m_outstr, " "); } return m_outstr.Length > firstN ? m_outstr.Substring(0, firstN) : m_outstr; } /// <summary> /// 此私有方法返回一個IP地址對應的無符號整數 /// </summary> /// <param name="x">IP地址</param> /// <returns></returns> private uint getuintFromIP(IPAddress x) { Byte[] bt = x.GetAddressBytes(); uint i = (uint)(bt[0] * 256 * 256 * 256); i += (uint)(bt[1] * 256 * 256); i += (uint)(bt[2] * 256); i += (uint)(bt[3]); return i; } #endregion #region 公有文法 /// <summary> /// 此公有方法提取網頁中一定字數的純文本，包括鏈接文字 /// </summary> /// <param name="firstN">字數</param> /// <returns></returns> public string getContext(int firstN) { return getFirstNchar(m_html, firstN, true); } /// <summary> /// 此公有方法提取網頁中一定字數的純文本，不包括鏈接文字 /// </summary> /// <param name="firstN"></param> /// <returns></returns> public string getContextWithOutLink(int firstN) { return getFirstNchar(m_html, firstN, false); } /// <summary> /// 此公有方法從本網頁的鏈接中提取一定數量的鏈接，該鏈接的URL滿足某正則式 /// </summary> /// <param name="pattern">正則式</param> /// <param name="count">返回的鏈接的個數</param> /// <returns>List<Link></returns> public List<Link> getSpecialLinksByUrl(string pattern,int count) { if(m_links.Count==0)getLinks(); List<Link> SpecialLinks = new List<Link>(); List<Link>.Enumerator i; i = m_links.GetEnumerator(); int cnt = 0; while (i.MoveNext() && cnt<count) { if (new Regex(pattern, RegexOptions.Multiline | RegexOptions.IgnoreCase ).Match(i.Current.url).Success) { SpecialLinks.Add(i.Current); cnt++; } } return SpecialLinks; } /// <summary> /// 此公有方法從本網頁的鏈接中提取一定數量的鏈接，該鏈接的文字滿足某正則式 /// </summary> /// <param name="pattern">正則式</param> /// <param name="count">返回的鏈接的個數</param> /// <returns>List<Link></returns> public List<Link> getSpecialLinksByText(string pattern,int count) { if (m_links.Count == 0) getLinks(); List<Link> SpecialLinks = new List<Link>(); List<Link>.Enumerator i; i = m_links.GetEnumerator(); int cnt = 0; while (i.MoveNext() && cnt < count) { if (new Regex(pattern, RegexOptions.Multiline | RegexOptions.IgnoreCase ).Match(i.Current.text).Success) { SpecialLinks.Add(i.Current); cnt++; } } return SpecialLinks; } /// <summary> /// 此公有方法獲得所有鏈接中在一定IP范圍的鏈接 /// </summary> /// <param name="_ip_start">起始IP</param> /// <param name="_ip_end">終止IP</param> /// <returns></returns> public List<Link> getSpecialLinksByIP(string _ip_start, string _ip_end) { IPAddress ip_start = IPAddress.Parse(_ip_start); IPAddress ip_end = IPAddress.Parse(_ip_end); if (m_links.Count == 0) getLinks(); List<Link> SpecialLinks = new List<Link>(); List<Link>.Enumerator i; i = m_links.GetEnumerator(); while (i.MoveNext()) { IPAddress ip; try { ip = Dns.GetHostEntry(new Uri(i.Current.url).Host).AddressList[0]; } catch { continue; } if(getuintFromIP(ip)>=getuintFromIP(ip_start) && getuintFromIP(ip)<=getuintFromIP(ip_end)) { SpecialLinks.Add(i.Current); } } return SpecialLinks; } /// <summary> /// 這公有方法提取本網頁的純文本中滿足某正則式的文字 /// </summary> /// <param name="pattern">正則式</param> /// <returns>返回文字</returns> public string getSpecialWords(string pattern) { if (m_outstr == "") getContext(Int16.MaxValue); Regex regex = new Regex(pattern, RegexOptions.Multiline | RegexOptions.IgnoreCase ); Match mc=regex.Match(m_outstr); if (mc.Success) return mc.Groups[1].Value; return string.Empty; } #endregion #region 構造函數 private void Init(string _url) { try { m_uri = new Uri(_url); m_links = new List<Link>(); m_html = ""; m_outstr = ""; m_title = ""; m_good = true; if (_url.EndsWith(".rar") || _url.EndsWith(".dat") || _url.EndsWith(".msi")) { m_good = false; return; } HttpWebRequest rqst = (HttpWebRequest)WebRequest.Create(m_uri); rqst.AllowAutoRedirect = true; rqst.MaximumAutomaticRedirections = 3; rqst.UserAgent = "Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)"; rqst.KeepAlive = true; rqst.Timeout = 30000; lock (WebPage.webcookies) { if (WebPage.webcookies.ContainsKey(m_uri.Host)) rqst.CookieContainer = WebPage.webcookies[m_uri.Host]; else { CookieContainer cc = new CookieContainer(); WebPage.webcookies[m_uri.Host] = cc; rqst.CookieContainer = cc; } } HttpWebResponse rsps = (HttpWebResponse)rqst.GetResponse(); Stream sm = rsps.GetResponseStream(); if (!rsps.ContentType.ToLower().StartsWith("text/") || rsps.ContentLength > 1 << 22) { rsps.Close(); m_good = false; return; } Encoding cding = System.Text.Encoding.Default; string contenttype=rsps.ContentType.ToLower(); int ix = contenttype.IndexOf("charset="); if (ix != -1) { try { cding = System.Text.Encoding.GetEncoding(rsps.ContentType.Substring(ix + "charset".Length + 1)); } catch { cding = Encoding.Default; } m_html = new StreamReader(sm, cding).ReadToEnd(); } else { m_html = new StreamReader(sm, cding).ReadToEnd(); Regex regex = new Regex("charset=(?<cding>[^=]+)?"",RegexOptions.IgnoreCase); string strcding = regex.Match(m_html).Groups["cding"].Value; try { cding = Encoding.GetEncoding(strcding); } catch{ cding = Encoding.Default; } byte[] bytes=Encoding.Default.GetBytes(m_html.ToCharArray()); m_html = cding.GetString(bytes); if (m_html.Split('?').Length > 100) { m_html=Encoding.Default.GetString(bytes); } } m_pagesize = m_html.Length; m_uri = rsps.ResponseUri; rsps.Close(); } catch (Exception ex) { Console.WriteLine(ex.Message+m_uri.ToString()); m_good = false; } } public WebPage(string _url) { string uurl = ""; try { uurl = Uri.UnescapeDataString(_url); _url = uurl; } catch { }; Regex re = new Regex("(?<h>[^x00-xff]+)"); Match mc = re.Match(_url); if (mc.Success) { string han = mc.Groups["h"].Value; _url = _url.Replace(han, System.Web.HttpUtility.UrlEncode(han, Encoding.GetEncoding("GB2312"))); } Init(_url); } public WebPage(string _url, string _loginurl, string _post) { string uurl = ""; try { uurl = Uri.UnescapeDataString(_url); _url = uurl; } catch { }; Regex re = new Regex("(?<h>[^x00-xff]+)"); Match mc = re.Match(_url); if (mc.Success) { string han = mc.Groups["h"].Value; _url = _url.Replace(han, System.Web.HttpUtility.UrlEncode(han, Encoding.GetEncoding("GB2312"))); } if (_loginurl.Trim() == "" || _post.Trim() == "" || WebPage.webcookies.ContainsKey(new Uri(_url).Host)) { Init(_url); } else { #region 登陸 string indata = _post; m_post = _post; m_loginurl = _loginurl; byte[] bytes = Encoding.Default.GetBytes(_post); CookieContainer myCookieContainer = new CookieContainer(); try { //新建一個CookieContainer來存放Cookie集合 HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(_loginurl); //新建一個HttpWebRequest myHttpWebRequest.ContentType = "application/x-www-form-urlencoded"; myHttpWebRequest.AllowAutoRedirect = false; myHttpWebRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)"; myHttpWebRequest.Timeout = 60000; myHttpWebRequest.KeepAlive = true; myHttpWebRequest.ContentLength = bytes.Length; myHttpWebRequest.Method = "POST"; myHttpWebRequest.CookieContainer = myCookieContainer; //設置HttpWebRequest的CookieContainer為剛才建立的那個myCookieContainer Stream myRequestStream = myHttpWebRequest.GetRequestStream(); myRequestStream.Write(bytes, 0, bytes.Length); myRequestStream.Close(); HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse(); foreach (Cookie ck in myHttpWebResponse.Cookies) { myCookieContainer.Add(ck); } myHttpWebResponse.Close(); } catch { Init(_url); return; } #endregion #region 登陸後再訪問頁面 try { m_uri = new Uri(_url); m_links = new List<Link>(); m_html = ""; m_outstr = ""; m_title = ""; m_good = true; if (_url.EndsWith(".rar") || _url.EndsWith(".dat") || _url.EndsWith(".msi")) { m_good = false; return; } HttpWebRequest rqst = (HttpWebRequest)WebRequest.Create(m_uri); rqst.AllowAutoRedirect = true; rqst.MaximumAutomaticRedirections = 3; rqst.UserAgent = "Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)"; rqst.KeepAlive = true; rqst.Timeout = 30000; rqst.CookieContainer = myCookieContainer; lock (WebPage.webcookies) { WebPage.webcookies[m_uri.Host] = myCookieContainer; } HttpWebResponse rsps = (HttpWebResponse)rqst.GetResponse(); Stream sm = rsps.GetResponseStream(); if (!rsps.ContentType.ToLower().StartsWith("text/") || rsps.ContentLength > 1 << 22) { rsps.Close(); m_good = false; return; } Encoding cding = System.Text.Encoding.Default; int ix = rsps.ContentType.ToLower().IndexOf("charset="); if (ix != -1) { try { cding = System.Text.Encoding.GetEncoding(rsps.ContentType.Substring(ix + "charset".Length + 1)); } catch { cding = Encoding.Default; } } m_html = new StreamReader(sm, cding).ReadToEnd(); m_pagesize = m_html.Length; m_uri = rsps.ResponseUri; rsps.Close(); } catch (Exception ex) { Console.WriteLine(ex.Message+m_uri.ToString()); m_good = false; } #endregion } } #endregion #region 屬性 /// <summary> /// 通過此屬性可獲得本網頁的網址，只讀 /// </summary> public string URL { get { return m_uri.AbsoluteUri; } } /// <summary> /// 通過此屬性可獲得本網頁的標題，只讀 /// </summary> public string Title { get { if (m_title == "") { Regex reg = new Regex(@"(?m)<title[^>]*>(?<title>(?:w|W)*?)</title[^>]*>", RegexOptions.Multiline | RegexOptions.IgnoreCase ); Match mc = reg.Match(m_html); if (mc.Success) m_title= mc.Groups["title"].Value.Trim(); } return m_title; } } /// <summary> /// 此屬性獲得本網頁的所有鏈接信息，只讀 /// </summary> public List<Link> Links { get { if (m_links.Count == 0) getLinks(); return m_links; } } /// <summary> /// 此屬性返回本網頁的全部純文本信息，只讀 /// </summary> public string Context { get { if (m_outstr == "") getContext(Int16.MaxValue); return m_outstr; } } /// <summary> /// 此屬性獲得本網頁的大小 /// </summary> public int PageSize { get { return m_pagesize; } } /// <summary> /// 此屬性獲得本網頁的所有站內鏈接 /// </summary> public List<Link> InsiteLinks { get { return getSpecialLinksByUrl("^http://"+m_uri.Host,Int16.MaxValue); } } /// <summary> /// 此屬性表示本網頁是否可用 /// </summary> public bool IsGood { get { return m_good; } } /// <summary> /// 此屬性表示網頁的所在的網站 /// </summary> public string Host { get { return m_uri.Host; } } /// <summary> /// 此網頁的登陸頁所需的POST數據 /// </summary> public string PostStr { get { return m_post; } } /// <summary> /// 此網頁的登陸頁 /// </summary> public string LoginURL { get { return m_loginurl; } } #endregion } /// <summary> /// 鏈接類 /// </summary> public class Link { public string url; //鏈接網址 public string text; //鏈接文字 public Link(string _url, string _text) { url = _url; text = _text; } }希望本文所述對大家的C#程序設計有所幫助。
