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CollectionHelper-網頁采集輔助類
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;
namespace Helper
{
/// <summary>
/// 網頁采集輔助類
/// </summary>
public static class CollectionHelper
{
/// <summary>
/// 取得字符裏的Dom元素 不包含元素屬性
/// </summary>
/// <param name="source"></param>
/// <param name="domElem"></param>
/// <returns></returns>
public static List<string> GetDomElem(string source, string domElem)
{
var matchList = new List<string>();
string regStr = string.Format("<{0}[^>]*?>[\\s\\S]+?<\\/{0}>", domElem);
try
{
var regex = new Regex(regStr, RegexOptions.Compiled | RegexOptions.IgnoreCase);
MatchCollection matches = regex.Matches(source);
foreach (Match match in matches)
{
matchList.Add(match.Value);
}
}
catch (Exception ex)
{
matchList.Add(ex.Message);
}
return matchList;
}
/// <summary>
/// 取得字符裏的Dom元素 包含元素屬性 如：
/// </summary>
/// <param name="source"></param>
/// <param name="tagName"></param>
/// <param name="tagValue"></param>
/// <returns></returns>
public static List<string> GetDomElemByAttr(string source, string tagName, string tagValue)
{
var matchList = new List<string>();
string regStr =
string.Format(
@"<(?<HtmlTag>[\w]+)[^>]*\s{0}[\s]*?=[\s]*?(?<Quote>[""']?){1}(?(Quote)\k<Quote>)[""']?[^>]*>((?<Nested><\k<HtmlTag>[^>]*>)|</\k<HtmlTag>>(?<-Nested>)|[\s\S]*?)*</\k<HtmlTag>>",
tagName.ToLower(), tagValue);
try
{
var regex = new Regex(regStr, RegexOptions.Compiled | RegexOptions.IgnoreCase);
MatchCollection matches = regex.Matches(source);
foreach (Match match in matches)
{
matchList.Add(match.Value);
}
}
catch (Exception ex)
{
matchList.Add(ex.Message);
}
return matchList;
}
/// <summary>
/// 取得字符裏的A元素鍵值對 [name，url]
/// </summary>
/// <param name="source"></param>
/// <returns></returns>
public static Dictionary<string, string> GetDomElem_A(string source)
{
var matchList = new Dictionary<string, string>();
const string pattern = "<a[^>]*? href=[\"'](?<url>[^\"']*?)[\"'][^>]*?>(?<text>[\\w\\W]*?)</a>";
try
{
var regex = new Regex(pattern, RegexOptions.Compiled | RegexOptions.IgnoreCase);
MatchCollection matches = regex.Matches(source);
foreach (Match match in matches)
{
string key = RemoveHtml(match.Value);
if (!matchList.ContainsKey(key))
{
matchList.Add(key, GetUrlArray(match.Value)[0]);
}
}
}
catch (Exception ex)
{
matchList.Add(ex.Message, "");
}
return matchList;
}
/// <summary>
/// 獲取頁麵內容後，用匹配url正則表達式抓取內容中的url
/// </summary>
/// <param name="code">列表代碼</param>
/// <returns>返回截取後的URL地址</returns>
public static List<string> GetUrlArray(string code)
{
var urlList = new List<string>();
var regex =
new Regex(@"(https://)?[\w-\.]*([\/]?[\w-])+[\w-]*\.(htm|html|shtm|shtml|aspx|asp|php|jsp)+[\w-\=\?]*",
RegexOptions.Compiled | RegexOptions.IgnoreCase);
MatchCollection matches = regex.Matches(code);
foreach (Match match in matches)
{
urlList.Add(match.Value);
}
return urlList;
}
/// <summary>
/// 獲取內容code中所有都圖片地址
/// </summary>
/// <returns>返回截取後都圖片地址</returns>
public static Dictionary<string, string> GetImgUrlArray(string content)
{
var imgList = new Dictionary<string, string>();
var reg = new Regex(@"<img[\s\S]*?src=(""(?<src>[^']*?)""|'(?<src>[^']*?)'|(?<src>[^>\s]*))[^>]*?>(.*?)");
MatchCollection m = reg.Matches(content.ToLower());
foreach (Match match in m)
{
string matchValue = match.Groups["src"].Value;
if (!imgList.ContainsKey(matchValue))
{
imgList.Add(matchValue, matchValue);
}
}
return imgList;
}
/// <summary>
/// 將相對地址轉換為絕對地址
/// </summary>
/// <param name="relativeAddress">要轉換的相對地址</param>
/// <param name="absoluteAddress">當前網頁地址</param>
/// <returns>返回轉換後的地址</returns>
public static string ConvertToAbsluteUrl(string relativeAddress, string absoluteAddress)
{
if (string.IsNullOrEmpty(relativeAddress))
{
return string.Empty;
}
if (relativeAddress.Contains("://"))
{
return relativeAddress;
}
if (string.IsNullOrEmpty(absoluteAddress))
{
return string.Empty;
}
if (!absoluteAddress.Contains("://"))
{
return string.Empty;
}
var baseUrl = new Uri(absoluteAddress);
var webrul = new Uri(baseUrl, relativeAddress);
return webrul.ToString();
}
/// <summary>
/// 替換所有HTML標簽為空
/// </summary>
/// <param name="input">The string whose values should be replaced.</param>
/// <returns>A string.</returns>
public static string RemoveHtml(string input)
{
var stripTags = new Regex("</?[a-z][^<>]*>", RegexOptions.IgnoreCase);
return stripTags.Replace(input, string.Empty);
}
/// <summary>
/// 移除字符串中的空格及換行符
/// </summary>
/// <param name="input">The string whose values should be replaced.</param>
/// <returns>A string.</returns>
public static string RemoveBlank(string input)
{
input = input.Replace("\r", string.Empty);
input = input.Replace("\n", string.Empty);
input = input.Replace(" ", string.Empty);
return input;
}
// 獲取網頁的HTML內容，根據網頁的charset自動判斷Encoding
public static string GetHtml(string url)
{
return GetHtml(url, null);
}
// 獲取網頁的HTML內容，指定Encoding
private static string GetHtml(string url, Encoding encoding)
{
string getSource;
try
{
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 || (Equals(encoding, Encoding.UTF8))) return html;
getSource = encoding.GetString(buf);
}
catch (NotSupportedException exception)
{
getSource = exception.Message;
}
catch (InvalidOperationException exception)
{
getSource = exception.Message;
}
catch (IOException exception)
{
getSource = exception.Message;
}
return getSource;
}
/// <summary>
/// 根據網頁的HTML內容提取網頁的Encoding
/// </summary>
/// <param name="html"></param>
/// <returns></returns>
private static Encoding GetEncoding(string html)
{
const 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;
}
}
}
}
最後更新：2017-04-02 06:52:15