public static class HtmlHelper { /// <summary> /// 按文本内容长度截取HTML字符串(支持截取带HTML代码样式的字符串) /// </summary> /// <param name="html">将要截取的字符串参数</param> /// <param name="len">截取的字节长度</param> /// <param name="endString">字符串末尾补上的字符串</param> /// <returns>返回截取后的字符串</returns> public static string HTMLSubstring(string html, int len, string endString) { if (string.IsNullOrEmpty(html) || html.Length <= len) return html; MatchCollection mcentiry, mchtmlTag; ArrayList inputHTMLTag = new ArrayList(); string r = "", tmpValue; int rWordCount = 0, wordNum = 0, i = 0; Regex rxSingle = new Regex("^<(br|hr|img|input|param|meta|link)", RegexOptions.Compiled | RegexOptions.IgnoreCase)//是否单标签正则 , rxEndTag = new Regex("</[^>]+>", RegexOptions.Compiled)//是否结束标签正则 , rxTagName = new Regex("<([a-z]+)[^>]*>", RegexOptions.Compiled | RegexOptions.IgnoreCase)//获取标签名正则 , rxHtmlTag = new Regex("<[^>]+>", RegexOptions.Compiled)//html标签正则 , rxEntity = new Regex("&[a-z]{1,9};", RegexOptions.Compiled | RegexOptions.IgnoreCase)//实体正则 , rxEntityReverse = new Regex("§", RegexOptions.Compiled)//反向替换实体正则 ; html = html.Replace("§", "§");//替换字符§为他的实体“§”，以便进行下一步替换 mcentiry = rxEntity.Matches(html);//收集实体对象到匹配数组中 html = rxEntity.Replace(html, "§");//替换实体为特殊字符§，这样好控制一个实体占用一个字符 mchtmlTag = rxHtmlTag.Matches(html);//收集html标签到匹配数组中 html = rxHtmlTag.Replace(html, "__HTMLTag__");//替换为特殊标签 string[] arrWord = html.Split(new string[] { "__HTMLTag__" }, StringSplitOptions.None);//通过特殊标签进行拆分 wordNum = arrWord.Length; //获取指定内容长度及HTML标签 for (; i < wordNum; i++) { if (rWordCount + arrWord[i].Length >= len) r += arrWord[i].Substring(0, len - rWordCount) + endString; else r += arrWord[i]; rWordCount += arrWord[i].Length;//计算已经获取到的字符长度 if (rWordCount >= len) break; //搜集已经添加的非单标签，以便封闭HTML标签对 if (i < wordNum - 1) { tmpValue = mchtmlTag[i].Value; if (!rxSingle.IsMatch(tmpValue)) { //不是单标签 if (rxEndTag.IsMatch(tmpValue) && inputHTMLTag.Count > 0) inputHTMLTag.RemoveAt(inputHTMLTag.Count - 1); else inputHTMLTag.Add(tmpValue); } r += tmpValue; } } //替换回实体 for (i = 0; i < mcentiry.Count; i++) r = rxEntityReverse.Replace(r, mcentiry[i].Value, 1); //封闭标签 for (i = inputHTMLTag.Count - 1; i >= 0; i--) r += "</" + rxTagName.Match(inputHTMLTag[i].ToString()).Groups[1].Value + ">"; return r; } /// <summary> /// 过滤html格式 /// </summary> /// <param name="Htmlstring"></param> /// <returns></returns> public static string NoHTML(this string Htmlstring) { Htmlstring = Regex.Replace(Htmlstring, @"<script[sS]*?</script>", "", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"<noscript[sS]*?</noscript>", "", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"<style[sS]*?</style>", "", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"<.*?>", "", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"<(.[^>]*)>", " ", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"([ ])[s]+", " ", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"-->", " ", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"<!--.*", " ", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"&(quot|#34);", """, RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"&(amp|#38);", "&", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"&(lt|#60);", "<", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"&(gt|#62);", ">", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"&(nbsp|#160);", "", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"&(iexcl|#161);", "xa1", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"&(cent|#162);", "xa2", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"&(pound|#163);", "xa3", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"&(copy|#169);", "xa9", RegexOptions.IgnoreCase); Htmlstring = Regex.Replace(Htmlstring, @"&#(d+);", " ", RegexOptions.IgnoreCase); return Htmlstring; } /// <summary> /// 去除html标签后并截取字符串 /// </summary> /// <param name="html">源html</param> /// <param name="length">截取长度</param> /// <returns></returns> public static string RemoveHtmlTag(this string html, int length = 0) { var doc = new HtmlDocument(); doc.LoadHtml(html); var strText = doc.DocumentNode.InnerText; if (length > 0 && strText.Length > length) { return strText.Substring(0, length); } return strText; } /// <summary> /// 补全HTMl标签 /// </summary> /// <param name="html">源html</param> /// <param name="length">截取长度</param> /// <returns></returns> public static string GetHtmlTag(this string html) { var doc = new HtmlDocument(); doc.LoadHtml(html); var strText = doc.DocumentNode.InnerHtml; return strText; } /// <summary> /// 转换为HtmlDecode /// </summary> /// <param name="value"></param> /// <returns></returns> public static string HtmlDecode(this string value) { return System.Net.WebUtility.HtmlDecode(value); } /// <summary> /// 转换为HtmlEncode /// </summary> /// <param name="value"></param> /// <returns></returns> public static string HtmlEncode(this string value) { return System.Net.WebUtility.HtmlEncode(value); } }