public static void Distory()
 {
     if (_thiz != null)
     {
         if (_thiz._list != null)
         {
             _thiz._list = null;
             _thiz._itemKeyDic = null;
             _thiz._invenKeyDic = null;
         }
         _thiz = null;
     }
 }
 public static StockWrapperDirector GetInstance()
 {
     if (_thiz == null)
         _thiz = new StockWrapperDirector();
     return _thiz;
 }