服务器封装JSON关键代码

StringBuilder sblist = new StringBuilder();
            XmlDocument xmldoc = new XmlDocument();
            xmldoc.Load(Server.MapPath("Show.config"));
            XmlNode xx = xmldoc.SelectSingleNode(RootItem);
            XmlNodeList nnlist = xx.SelectNodes("Category");
            XmlNode xnxn = nnlist.Item(0);
            XmlNodeList nodelist = xnxn.SelectNodes("Item");
            XmlNode nodeitem = null;
            XmlNodeList snodelist = null;
            XmlNode snode = null;
            sblist.Append("[");
            for (int i = 0; i < nodelist.Count; i++)
            {
                nodeitem = nodelist.Item(i);
                if (act == "loaddata")
                {
                    if (nodeitem["expand"].InnerText.ToString() == "0")
                    {
                        sblist.Append("{\"id\":\"" + nodeitem["id"].InnerText + "\"," + "\"name\":\"" + nodeitem["name"].InnerText + "\",\"img\":\""+nodeitem["img"].InnerText+"\"");
                        snodelist = nodeitem.SelectNodes("SItem");
                        if (snodelist.Count <= 0)
                        {
                            sblist.Append("},");
                        }
                        else
                        {
                            sblist.Append(",");
                            if (snodelist.Count > 1)
                            {
                                sblist.Append("SItem:[");
                            }
                            for (int j = 0; j < snodelist.Count; j++)
                            {
                                snode = snodelist.Item(j);
                                if (snodelist.Count > 1)
                                {
                                    sblist.Append("{\"id\":\"" + snode["id"].InnerText + "\",\"name\":\"" + snode["name"].InnerText + "\",\"img\":\""+snode["img"].InnerText+"\"},");
                                }
                                else
                                {
                                    sblist.Append("\"SItem\":[{\"id\":\"" + snode["id"].InnerText + "\",\"name\":\"" + snode["name"].InnerText + "\",\"img\":\""+snode["img"].InnerText+"\"}],");
                                }
                            }
                            if (snodelist.Count > 1)
                            {
                                sblist.Append("]");
                                sblist.Remove(sblist.Length - 2, 1);
                            }
                            else
                            {
                                sblist.Remove(sblist.Length - 1, 1);
                            }
                            sblist.Append("},");
                        }
                    }
                }
            }
            //清除最后一个}外面的,
            sblist.Remove(sblist.Length - 1, 1);
            sblist.Append("]");
            Response.ContentType = "application/json";
            Response.ContentEncoding = Encoding.UTF8;
            Response.Write(sblist.ToString());
            Response.End();
        }
        protected void Page_Load(object sender, EventArgs e)
        {
   act = Request.QueryString["act"];
            if (act != string.Empty)
            {
                if (act == "loaddata")
                {
                    LoadXml(act,"Config");
                }
                if (act == "save")
                {
                    Save("Config");
                }
            }
        }