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C#实现抓取和分析网页类实例
本文实例讲述了C#实现抓取和分析网页类。分享给大家供大家参考。具体分析如下：
这里介绍了抓取和分析网页的类。
其主要功能有：
1、提取网页的纯文本，去所有html标签和javascript代码
2、提取网页的链接，包括href和frame及iframe
3、提取网页的title等(其它的标签可依此类推，正则是一样的)
4、可以实现简单的表单提交及cookie保存
/*
* Author:Sunjoy at CCNU
* 如果您改进了这个类请发一份代码给我(ccnusjy 在gmail.com)
*/
using System;
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>
/// 网页类
/// </summary>
public class WebPage
{
#region 私有成员
private Uri m_uri; //网址
private List<Link> m_links; //此网页上的链接
private string m_title; //此网页的标题
private string m_html; //此网页的HTML代码
private string m_outstr; //此网页可输出的纯文本
private bool m_good; //此网页是否可用
private int m_pagesize; //此网页的大小
private static Dictionary<string, CookieContainer> webcookies = new Dictionary<string, CookieContainer>();//存放所有网页的Cookie
private string m_post; //此网页的登陆页需要的POST数据
private string m_loginurl; //此网页的登陆页
#endregion
#region 私有方法
/// <summary>
/// 这私有方法从网页的HTML代码中分析出链接信息
/// </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>
/// 此私有方法从一段HTML文本中提取出一定字数的纯文本
/// </summary>
/// <param name="instr">HTML代码</param>
/// <param name="firstN">提取从头数多少个字</param>
/// <param name="withLink">是否要链接里面的字</param>
/// <returns>纯文本</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>
/// 此私有方法返回一个IP地址对应的无符号整数
/// </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>
/// 此公有方法提取网页中一定字数的纯文本，包括链接文字
/// </summary>
/// <param name="firstN">字数</param>
/// <returns></returns>
public string getContext(int firstN)
{
return getFirstNchar(m_html, firstN, true);
}
/// <summary>
/// 此公有方法提取网页中一定字数的纯文本，不包括链接文字
/// </summary>
/// <param name="firstN"></param>
/// <returns></returns>
public string getContextWithOutLink(int firstN)
{
return getFirstNchar(m_html, firstN, false);
}
/// <summary>
/// 此公有方法从本网页的链接中提取一定数量的链接，该链接的URL满足某正则式
/// </summary>
/// <param name="pattern">正则式</param>
/// <param name="count">返回的链接的个数</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>
/// 此公有方法从本网页的链接中提取一定数量的链接，该链接的文字满足某正则式
/// </summary>
/// <param name="pattern">正则式</param>
/// <param name="count">返回的链接的个数</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>
/// 此公有方法获得所有链接中在一定IP范围的链接
/// </summary>
/// <param name="_ip_start">起始IP</param>
/// <param name="_ip_end">终止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>
/// 这公有方法提取本网页的纯文本中满足某正则式的文字
/// </summary>
/// <param name="pattern">正则式</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 构造函数
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 登陆
string indata = _post;
m_post = _post;
m_loginurl = _loginurl;
byte[] bytes = Encoding.Default.GetBytes(_post);
CookieContainer myCookieContainer = new CookieContainer();
try
{
//新建一个CookieContainer来存放Cookie集合
HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(_loginurl);
//新建一个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;
//设置HttpWebRequest的CookieContainer为刚才建立的那个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 登陆后再访问页面
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 属性
/// <summary>
/// 通过此属性可获得本网页的网址，只读
/// </summary>
public string URL
{
get
{
return m_uri.AbsoluteUri;
}
}
/// <summary>
/// 通过此属性可获得本网页的标题，只读
/// </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>
/// 此属性获得本网页的所有链接信息，只读
/// </summary>
public List<Link> Links
{
get
{
if (m_links.Count == 0) getLinks();
return m_links;
}
}
/// <summary>
/// 此属性返回本网页的全部纯文本信息，只读
/// </summary>
public string Context
{
get
{
if (m_outstr == "") getContext(Int16.MaxValue);
return m_outstr;
}
}
/// <summary>
/// 此属性获得本网页的大小
/// </summary>
public int PageSize
{
get
{
return m_pagesize;
}
}
/// <summary>
/// 此属性获得本网页的所有站内链接
/// </summary>
public List<Link> InsiteLinks
{
get
{
return getSpecialLinksByUrl("^http://"+m_uri.Host,Int16.MaxValue);
}
}
/// <summary>
/// 此属性表示本网页是否可用
/// </summary>
public bool IsGood
{
get
{
return m_good;
}
}
/// <summary>
/// 此属性表示网页的所在的网站
/// </summary>
public string Host
{
get
{
return m_uri.Host;
}
}
/// <summary>
/// 此网页的登陆页所需的POST数据
/// </summary>
public string PostStr
{
get
{
return m_post;
}
}
/// <summary>
/// 此网页的登陆页
/// </summary>
public string LoginURL
{
get
{
return m_loginurl;
}
}
#endregion
}
/// <summary>
/// 链接类
/// </summary>
public class Link
{
public string url; //链接网址
public string text; //链接文字
public Link(string _url, string _text)
{
url = _url;
text = _text;
}
}
希望本文所述对大家的C#程序设计有所帮助
来源：https://www.jb51.net/article/66663.htm
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