如何使用mvcsitemapprovider将自定义xml标记添加到sitemap.xml？

public ContentResult VideoSiteMap()
    {
        XmlDocument xmlDoc = new XmlDocument();
        using (XmlWriter writer = xmlDoc.CreateNavigator().AppendChild())
        {
            //writer.Formatting = Formatting.Indented;
            writer.WriteStartDocument();
            writer.WriteStartElement("urlset","http://www.sitemaps.org/schemas/sitemap/0.9");

            // add namespaces
            writer.WriteAttributeString("xmlns","video",null,"http://www.google.com/schemas/sitemap-video/1.1");
            List<VideoSiteMap> siteMapp = null;
            siteMapp = ServiceHelper.GetGoogleSiteMap();//I invoked a service
            //you can use a fake loop instead: for (int i = 0; i < 10; i++)
            foreach( var content in siteMapp)
            {
                writer.WriteStartElement("url");

                // required
                writer.WriteElementString("loc","http://example.com/myplayer.aspx");
                writer.WriteStartElement("video",null);

                // start:optional
                writer.WriteElementString("video","thumbnail_loc","http://www.example.com/thumbs/123.jpg");
                writer.WriteElementString("video","title","");
                writer.WriteElementString("video","description","Alkis shows you how to get perfectly done steaks every time");
                writer.WriteElementString("video","content_loc","http://www.example.com/video123.mp4");

                writer.WriteStartElement("video","player_loc",null);
                writer.WriteAttributeString("autoplay","ap=1");
                writer.WriteString("http://www.example.com/videoplayer.mp4?video=123");
                writer.WriteEndElement(); // video:player_loc
                                          // end:optional

                writer.WriteElementString("video","duration","100");
                writer.WriteElementString("video","expiration_date","2009-11-05T19:20:30+08:00");
                writer.WriteElementString("video","rating","4.2");
                writer.WriteElementString("video","view_count","12345");
                writer.WriteElementString("video","publication_date","2007-11-05T19:20:30+08:00");
                writer.WriteElementString("video","family_friendly","yes");
                writer.WriteElementString("video","category","Cooking");

                writer.WriteStartElement("video","restriction",null);
                writer.WriteAttributeString("relationship","allow");
                writer.WriteString("IE GB US CA");
                writer.WriteEndElement();

                writer.WriteStartElement("video","gallery_loc",null);
                writer.WriteAttributeString("title","Cooking Videos");
                writer.WriteString("http://cooking.example.com");
                writer.WriteEndElement();

                writer.WriteStartElement("video","price",null);
                writer.WriteAttributeString("currency","EUR");
                writer.WriteString("1.99");
                writer.WriteEndElement();

                writer.WriteElementString("video","requires_subscription","yes");

                writer.WriteStartElement("video","uploader",null);
                writer.WriteAttributeString("info","http://www.example.com/users/grillymcgrillerson");
                writer.WriteString("GrillyMcGrillerson");
                writer.WriteEndElement();

                writer.WriteElementString("video","live","No");

                writer.WriteEndElement(); // video:video
                writer.WriteEndElement(); //url
            }

            writer.WriteEndElement(); //urlset 
            writer.WriteEndDocument();
            writer.Close();
        }

        var stringWriter = new StringWriter();
        var xmlTextWriter = XmlWriter.Create(stringWriter);
        xmlDoc.WriteTo(xmlTextWriter);
        xmlTextWriter.Flush();
        return Content(stringWriter.GetStringBuilder().ToString().replace("utf-16","utf-8"),"text/xml",Encoding.UTF8);

    }

我在返回我的xml数据的同时用utf-8替换了utf-16,因为我找不到更简单的方法来更改XmlWriter的结果(默认情况下它总是返回一个utf-16格式)

我希望它可以帮助其他人,如果有人帮助我做一个nuget包或者其他东西,我会很高兴的：D