zTree默认展开树节点

jsp页面

$.getJSON("<%=webApp %>/pages/XXX/XXX.do?dqDate="+(new Date()).getTime(), function(zNodes){  

                var zTree = $.fn.zTree.init($("#roleTree"), setting, zNodes);
                var cNode = zTree.getNodeByParam("id", 0);  ///id为树头节点的id
                 zTree.expandNode(cNode, true, false);

  });

后台：              

   child.put("open", true);