/节点列表

    public function node(){

        if(!$node = S('node_list')){

            $field = array('id', 'name', 'title', 'pid');

            $node = M('node')->field($field)->order('sort')->select();

            $node = node_merge($node);

            S('node_list', $node, 3600);    //将节点列表缓存1小时

        }

        $this->node = $node;

        $this->display();

    }