code: private void refreshTree(HttpServletRequest request, TreeControl control) throws Exception {
      String key = request.getParameter("key");
      if (key != null) {
        ViewNode node = control.findNode(key);
        if (node != null) {
          Debug.logVerbose("[JdonFramework]Found Node: " + key, module);
          if (!node.isExpanded()) {
            //原来是叠合的，现在需要展开
            //需要查询数据库，将该节点下的子节点查询获取
            node.clearChildren();
            fetchChildern(request, node);
          }
          node.setExpanded(!node.isExpanded());
        } else {
          Debug.logVerbose("[JdonFramework]Node is null : " + key);
        }
      }
      // Handle a select item event
      String select = request.getParameter("select");
      if (select != null) {
          control.selectNode(select);
      }
  
    }
docs: 刷新树
  @param request HttpServletRequest
  @param control TreeControl
  @throws Exception