using System;
using System.Web.UI;
using System.Web;
using System.Text.RegularExpressions;
using System.Collections.Specialized;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;namespace JianCaiWeb.Utils
{public class FilterStrFactoryHandler : IHttpHandlerFactory{public virtual IHttpHandler GetHandler(HttpContext context, string requestType, string url, string pathTranslated){//得到编译实例(通过反射)
            PageHandlerFactory factory = (PageHandlerFactory) Activator.CreateInstance(typeof(PageHandlerFactory), true);IHttpHandler handler = factory.GetHandler(context, requestType, url, pathTranslated);//过滤字符串
            if (requestType == "POST"){Page page = handler as Page;if (page != null)page.PreLoad += new EventHandler(FilterStrFactoryHandler_PreLoad);}//返回
            return handler;}//过滤TextBox、Input和Textarea中的特殊字符
        void FilterStrFactoryHandler_PreLoad(object sender, EventArgs e){try{Page page = sender as Page;NameValueCollection postData = page.Request.Form;foreach (string postKey in postData){Control ctl = page.FindControl(postKey);if (ctl as TextBox != null){((TextBox) ctl).Text = Common.InputText(((TextBox) ctl).Text);continue;}if (ctl as HtmlInputControl != null){((HtmlInputControl) ctl).Value = Common.InputText(((HtmlInputControl) ctl).Value);continue;}if (ctl as HtmlTextArea != null){((HtmlTextArea) ctl).Value = Common.InputText(((HtmlTextArea) ctl).Value);continue;}}}catch{}}public virtual void ReleaseHandler(IHttpHandler handler){}}
}

using System.Text.RegularExpressions;
public class Common
{//字符串过滤
    public static string InputText(string text){text = text.Trim();if (string.IsNullOrEmpty(text))return string.Empty;text = Regex.Replace(text, "[\\s]{2,}", " ");    //two or more spaces
        text = Regex.Replace(text, "(<[b|B][r|R]/*>)+|(<[p|P](.|\\n)*?>)", "\n");    //<br>
        text = Regex.Replace(text, "(\\s*&[n|N][b|B][s|S][p|P];\\s*)+", " ");    //&nbsp;
        text = Regex.Replace(text, "<(.|\\n)*?>", string.Empty);    //any other tags
        text = text.Replace("'", "''");return text;}
}

<httpHandlers><!--过滤提交给服务器的文本信息--><add verb="*" path="*.aspx" validate="false" type="JianCaiWeb.Utils.FilterStrFactoryHandler, JianCaiWeb.Utils"/>
</httpHandlers>

<httpHandlers> <!--过滤提交给服务器的文本信息--> <add verb="*" path="*.aspx" validate="false" type="JianCaiWeb.Utils.FilterStrFactoryHandler, JianCaiWeb.Utils"/> </httpHandlers>