protected override void Render(HtmlTextWriter writer)
    {
        string name = Request.Url.AbsolutePath.Substring(1, Request.Url.AbsolutePath.Length - 1).Replace("aspx", "html");
        name = name.ToLower().Replace("aspx/", "");
        string newurl = "";
        if (name.IndexOf("/") > 0)
        {
            newurl = Server.MapPath("/") + name;
        }
        else
        {
            newurl = Server.MapPath("/") + name;
        }
        MemoryStream ms = new MemoryStream();
        StreamWriter sww = new StreamWriter(ms);
        StreamWriter swr = new StreamWriter(newurl);
        HtmlTextWriter htmlw = new HtmlTextWriter(swr);
        base.Render(htmlw);
        htmlw.Flush();
        htmlw.Close();
        string strLL = System.Text.Encoding.UTF8.GetString(ms.ToArray());
        Response.Write(strLL);
        string tourl = Request.Url.AbsoluteUri.ToLower().Replace(".aspx", "htm").Replace("aspx/", "");
        Response.Redirect(tourl, true);
    }

<section name="RewriterConfig" type="URLRewriter.Config.RewriterConfigSerializerSectionHandler, URLRewriter" />

configSections节点后
<RewriterConfig>
    <Rules>
      <RewriterRule>
        <LookFor><![CDATA[~/(\d+)\.htm]]></LookFor>
        <SendTo><![CDATA[~/index.aspx?pageNum=$1]]></SendTo>
      </RewriterRule>
    </Rules>
</RewriterConfig>


system.web节点里
<httpModules>
<add type="URLRewriter.ModuleRewriter, URLRewriter" name="ModuleRewriter" />
</httpModules>