CollectionHelper-网页采集辅助类代码,C#代码库,德仔网

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【C#】 CollectionHelper-网页采集辅助类
作者:彩连 / 发布于2016/7/27/ 563
using System;  
using System.Collections.Generic;  
using System.IO;  
using System.Net;  
using System.Text;  
using System.Text.RegularExpressions;  
  
namespace Helper  
{  
    /// <summary>  
    ///     网页采集辅助类  
    /// </summary>  
    public static class CollectionHelper  
    {  
        /// <summary>  
        ///     取得字符里的Dom元素 不包含元素属性  
        /// </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>  
        ///     取得字符里的Dom元素 包含元素属性 如：class="aa"  
        /// </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>  
        ///     取得字符里的A元素键值对  [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>  
        ///     获取页面内容后，用匹配url正则表达式抓取内容中的url  
        /// </summary>  
        /// <param name="code">列表代码</param>  
        /// <returns>返回截取后的URL地址</returns>  
        public static List<string> GetUrlArray(string code)  
        {  
            var urlList = new List<string>();  
            var regex =  
                new Regex(@"(http://)?[\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>  
        ///     获取内容code中所有都图片地址  
        /// </summary>  
        /// <returns>返回截取后都图片地址</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>  
        ///     将相对地址转换为绝对地址  
        /// </summary>  
        /// <param name="relativeAddress">要转换的相对地址</param>  
        /// <param name="absoluteAddress">当前网页地址</param>  
        /// <returns>返回转换后的地址</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>  
        ///     替换所有HTML标签为空  
        /// </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换行符  
        /// </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;  
        }  
  
        // 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)  
        {  
            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>  
        ///     根据网页的HTML内容提取网页的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;  
            }  
        }  
    }  
}
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