var zTree = $.fn.zTree.getZTreeObj('userDemo'); //ztree对象
                console.log(zTree);
                var nodeChecked=zTree.getNodeByParam("loginName",userName);//得到选中的节点
                zTree.checkNode(nodeChecked,!nodeChecked.checked, true);
                nodeChecked.checked = true;
                zTree.selectNode(nodeChecked,false,false);
                checked = zTree.getCheckedNodes(true);//得到选中的节点

zTree.checkAllNodes(false);//设置全部为false,不选中节点
zTree.cancelSelectedNode();