/// <summary>

        /// 此处过滤危险HTML方法

        /// </summary>

        /// <param name="html">html</param>

        /// <returns></returns>

        private string FilterHTML(string html)

        {

            if (html == null)

                return "";

            //过滤 script

            Regex regex_script1 = new Regex("(<script[//s//S]*?///script//s*>)", RegexOptions.IgnoreCase);

            Regex regex_script2 = new Regex("(<(script[//s//S]*?)>)", RegexOptions.IgnoreCase);

            html = regex_script1.Replace(html, "");

            html = regex_script1.Replace(html, "");

            //过滤 <iframe> 标签

            Regex regex_iframe1 = new Regex("(<iframe [//s//S]+<iframe//s*>)", RegexOptions.IgnoreCase);

            Regex regex_iframe2 = new Regex("(<(iframe [//s//S]*?)>)", RegexOptions.IgnoreCase);

            html = regex_iframe1.Replace(html, "");

            html = regex_iframe2.Replace(html, "");

            //过滤 <frameset> 标签

            Regex regex_frameset1 = new Regex("(<frameset [//s//S]+<frameset //s*>)", RegexOptions.IgnoreCase);

            Regex regex_frameset2 = new Regex("(<(frameset [//s//S]*?)>)", RegexOptions.IgnoreCase);

            html = regex_frameset1.Replace(html, "");

            html = regex_frameset2.Replace(html, "");

            //过滤 <frame> 标签

            Regex regex_frame1 = new Regex("(<frame[//s//S]+<frame //s*>)", RegexOptions.IgnoreCase);

            Regex regex_frame2 = new Regex("(<(frame[//s//S]*?)>)", RegexOptions.IgnoreCase);

            html = regex_frame1.Replace(html, "");

            html = regex_frame2.Replace(html, "");

            //过滤 <form> 标签

            Regex regex_form1 = new Regex("(<(form [//s//S]*?)>)", RegexOptions.IgnoreCase);

            Regex regex_form2 = new Regex("(<(/form[//s//S]*?)>)", RegexOptions.IgnoreCase);

            html = regex_form1.Replace(html, "");

            html = regex_form2.Replace(html, "");

            //过滤 on: 的事件

            //过滤on 带单引号的 过滤on  带双引号的 过滤on 不带有引号的

            string regOn = @"<[//s//S]+ (on)[a-zA-Z]{4,20} *= *[//S ]{3,}>";

            string regOn2 = @"((on)[a-zA-Z]{4,20} *= *'[^']{3,}')|((on)[a-zA-Z]{4,20} *= */""[^/""]{3,}/"")|((on)[a-zA-Z]{4,20} *= *[^>/ ]{3,})";

            html = GetReplace(html, regOn, regOn2, "");

            //过滤 javascript: 的事件

            regOn = @"<[//s//S]+ (href|src|background|url|dynsrc|expression|codebase) *= *[ /""/']? *(javascript:)[//S]{1,}>";

            regOn2 = @"(' *(javascript|vbscript):([//S^'])*')|(/"" *(javascript|vbscript):[//S^/""]*/"")|([^=]*(javascript|vbscript):[^/> ]*)";

            html = GetReplace(html, regOn, regOn2, "");

            return html;

        }

        /// <summary>

        /// 正则双重过滤

        /// </summary>

        /// <param name="content"></param>

        /// <param name="splitKey1"></param>

        /// <param name="splitKey2"></param>

        /// <param name="newChars"></param>

        /// <returns></returns>

        private string GetReplace(string content, string splitKey1, string splitKey2, string newChars)

        {

            //splitKey1 第一个正则式匹配

            //splitKey2 匹配结果中再次匹配进行替换

            if (splitKey1 != null && splitKey1 != "" && splitKey2 != null && splitKey2 != "")

            {

                Regex rg = new Regex(splitKey1);

                System.Text.RegularExpressions.MatchCollection mc = rg.Matches(content);

                foreach (System.Text.RegularExpressions.Match mc1 in mc)

                {

                    string oldChar = mc1.ToString();

                    string newChar = new Regex(splitKey2, RegexOptions.IgnoreCase).Replace(oldChar, newChars);

                    content = content.Replace(oldChar, newChar);

                }

                return content;

            }

            else

            {

                if (splitKey2 != null && splitKey2 != "")

                {

                    Regex rg = new Regex(splitKey2, RegexOptions.IgnoreCase);

                    return rg.Replace(content, newChars);

                }

            }

            return content;

        }