Jquery EasyUI tree asynchronous loading (traverse the specified folder according to the folder files generated tree)

The asynchronous loading of Jquery EasyUI tree (traversing the specified folder and generating tree according to the files in the folder) is as follows:

private void SMT(HttpContext context)
 {
  string SqlConnection82 = System.Configuration.ConfigurationManager.AppSettings["LocalConnectionString"];
  string path = context.Server.MapPath(@"~/CISWeb/SMT_SOP");
  string id = string.Empty;
  List<string> filesNameList = getFiles(path);
  if (filesNameList.Count > 0)
   context.Response.Write(ListToJson(filesNameList,id));
  else
  {
   context.Response.Write("0");
  }  
 }
 /// <summary>
 ///  Object in the directory specified by the scope   Folder / Documents   Quantity 
 /// </summary>
 /// <param name="path"></param>
 /// <returns></returns>
 private static List<string> getFiles(string path)
 {
  DirectoryInfo SMT_SOP = new DirectoryInfo(path);
  List<string> allFileList = new List<string>();
  DirectoryInfo[] allDir = SMT_SOP.GetDirectories();// Get the number of folders 
  foreach (DirectoryInfo d in allDir)
  {
   allFileList.Add("0|" + d.Name);
  }
  FileInfo[] allFile = SMT_SOP.GetFiles();// Get the number of files 
  foreach (FileInfo fi in allFile)
  {
   allFileList.Add("1|" + fi.Name);
  }
  return allFileList;
 }
 /// <summary>
 ///  Traverses the specified folder and returns according to the files in the folder JSON
 /// </summary>
 /// <param name="filesNameList"></param>
 /// <param name="id"> No. 1 1 The next time this method is called, id=""</param>
 /// <returns></returns>
 public string ListToJson(List<string> filesNameList,string id)
 { 
  StringBuilder sb2 = new StringBuilder();
  sb2.Append("[");
  for (int i = 0; i < filesNameList.Count; i++)
  {  
   if (filesNameList[i].ToString().Split('|')[0] == "0")
   { 
    sb2.Append("{ \"id\":" +id+ (i + 1).ToString() + ",\"text\":\"" + filesNameList[i].ToString().Split('|')[1] + "\",\"state\":\"closed\",\"children\": [");    
    sb2.Append("]},");    
   }
   else
   {    
    sb2.Append("{\"id\":"+id + (i + 1).ToString() + ",\"text\":\"" + String.Format(filesNameList[i].ToString().Split('|')[1]) + "\"},");    
   }

  }
  sb2.Remove(sb2.Length - 1, 1);
  sb2.Append("]");  
  return sb2.ToString();
 }

Front desk

$.ajax({
   type: "post",
   url: "../../ajax/Handler.ashx?action=SMT",
   data: {},
   success: function (result) {
    $("#menuDiv").dialog("open");//jQuery UI Modal window in 
    var treeData = eval(result);
    $("#tt").tree({
     data: treeData})
    }
   })