项目中解决小问题的各种方法

 一、获取HTML标签中的文字内容 

   /// <summary>
    /// 去除HTML标记
    /// </summary>
    /// <param name="NoHTML">包括HTML的源码 </param>
    /// <returns>已经去除后的文字</returns>
    public static string NoHTML(string Htmlstring)
    {
        //删除脚本
        Htmlstring = Regex.Replace(Htmlstring, @"<script[^>]*?>.*?</script>", "", RegexOptions.IgnoreCase);
        //删除HTML
        Htmlstring = Regex.Replace(Htmlstring, @"<(.[^>]*)>", "", RegexOptions.IgnoreCase);
        Htmlstring = Regex.Replace(Htmlstring, @"([\r\n])[\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);
        Htmlstring.Replace("<", "");
        Htmlstring.Replace(">", "");
        Htmlstring.Replace("\r\n", "");
        Htmlstring = HttpContext.Current.Server.HtmlEncode(Htmlstring).Trim();
        return Htmlstring;
    }

二、截取字符串

    /// <summary>
    /// 截取字符串（按全角长度，一个全角等于两个半角）
    /// </summary>
    /// <param name="strSource">字符串</param>
    /// <param name="length">截取长度（全角）</param>
    /// <returns></returns>
    public static string InterceptString(string strSource, int length)
    {
        string strResult = InterceptString(strSource, length, 0);
        if (strResult == strSource)
        {
            return strResult;
        }
        else
        {
            return strResult + "...";
        }
    }
    private static string InterceptString(string str, int length, int length1)
    {
        if (str.Length > length)
        {
            if (length1 == 0)
            {
                length1 = length;
            }
            if (str.Length >= length1)
            {
                string str_left = str.Substring(0, length1);
                //string str_right = str.Remove(0, length1);
                int banjiao = 0, other = 0;
                char[] chars = str_left.Trim().ToCharArray();
                foreach (char ch in chars)
                {
                    if (ch >= 33 && ch <= 126)
                    {
                        banjiao++;
                    }
                    else
                    {
                        other++;
                    }
                }
                if ((other + (float)banjiao / 2) > length || (other + (float)banjiao / 2) - length == 0.5)
                {
                    str_left = str_left.Remove(str_left.Length - 1, 1);
                    return str_left;
                }
                else if ((other + (float)banjiao / 2) - length != 0)
                {
                    if (length1 + 1 <= str.Length)
                    {
                        str_left = InterceptString(str, length, length1 + 1);
                    }
                }
                return str_left;
            }
            else
            {
                return str;
            }
        }
        else
        {
            return str;
        }
    }

三、获取图片URL

　 /// <summary>
    /// 利用正则表达式获取文本中图片的URL
    /// </summary>
    /// <param name="sHtmlText">文本</param>
    /// <returns>返回图片路径集合</returns>
    public static string[] GetHtmlImageUrlList(string sHtmlText)
    {
        // 定义正则表达式用来匹配 img 标签
        Regex regImg = new Regex(@"<img\b[^<>]*?\bsrc[\s\t\r\n]*=[\s\t\r\n]*[""']?[\s\t\r\n]*(?<imgUrl>[^\s\t\r\n""'<>]*)[^<>]*?/?[\s\t\r\n]*>", RegexOptions.IgnoreCase);
        // 搜索匹配的字符串
        MatchCollection matches = regImg.Matches(sHtmlText);
        int i = 0;
        string[] sUrlList = new string[matches.Count];
        // 取得匹配项列表
        foreach (Match match in matches)
            sUrlList[i++] = match.Groups["imgUrl"].Value;
        return sUrlList;
    }