字符串 html之间的转换

  /**/
        /// <summary>
        ///将字符串格式化为HTML
        /// </summary>
        /// <param name="normalStr">所要格式化的字符串</param>
        /// <param name="identiftyURL">是否自动识别URL，识别出来的URL将会自动加上超级链接标签</param>
        /// <returns>返回格式化后的HTML代码</returns>
        public static string FormatToHTML(string normalStr, bool identiftyURL)
        {
            StringBuilder html = new StringBuilder(normalStr);

            html.Append(' ');
            html.Replace("&amp;", "&");
            html.Replace("&nbsp;", " ");
            html.Replace("&lt;", "<");
            html.Replace("&gt;", ">");
            html.Replace("&quot;", "\"");

            if (identiftyURL)
            {
                Regex linkRegex = new Regex("(http://|www)[\\S]{5,}(?=&nbsp;|\r\n)");

                MatchCollection regMathes = linkRegex.Matches(html.ToString());

                int add = 0;

                foreach (Match match in regMathes)
                {
                    string head = string.Format("<a href=\"{0}\">", match.Value[0] == 'h' ? match.Value : "http://" + match.Value);

                    html.Insert(match.Index + add, head);
                    add += head.Length;

                    html.Insert(match.Index + match.Length + add, "</a>");
                    add += 3;
                }
            }

            html.Replace("\r\n", "<br />");

            return html.ToString();
        }



        #region 过滤掉 html代码
        private static string StripHTML(string strHtml)
        {
            #region
            string[] aryReg ={ 
            @"<script[^>]*?>.*?</script>",  
            @"<(\/\s*)?!?((\w+:)?\w+)(\w+(\s*=?\s*(([""'])(\\[""'tbnr]|[^\7])*?\7|\w+)|.{0})|\s)*?(\/\s*)?>", 
            @"([\r\n])[\s]+", 
            @"&(quot|#34);", 
            @"&(amp|#38);", 
            @"&(lt|#60);", 
            @"&(gt|#62);", 
            @"&(nbsp|#160);", 
            @"&(iexcl|#161);", 
            @"&(cent|#162);", 
            @"&(pound|#163);", 
            @"&(copy|#169);", 
            @"&#(\d+);", 
            @"-->", 
            @"<!--.*\n" 
            };

            string[] aryRep = { 
            "", 
            "", 
            "", 
            "\"", 
            "&", 
            "<", 
            ">", 
            " ", 
            "\xa1",//chr(161), 
            "\xa2",//chr(162), 
            "\xa3",//chr(163), 
            "\xa9",//chr(169), 
            "", 
            "\r\n", 
            "" 
            };
            #endregion
            string newReg = aryReg[0];
            string strOutput = strHtml;
            for (int i = 0; i < aryReg.Length; i++)
            {
                System.Text.RegularExpressions.Regex regex = new System.Text.RegularExpressions.Regex(aryReg[i], System.Text.RegularExpressions.RegexOptions.IgnoreCase);
                strOutput = regex.Replace(strOutput, aryRep[i]);
            }
            strOutput.Replace("<", "");
            strOutput.Replace(">", "");
            strOutput.Replace("\r\n", "");
            return strOutput;
        }
        #endregion