/**
  * 
  * 分类列表
  */
 public function index()
 {
     #1.实例化PaperService类
     $PS = new PaperService();
     #2.调用方法获取所有分类
     $cates = $PS->getCates();
     //调用packCatesPapers方法获取分类下文章数量(is_del=1表示未删除)
     $cates = $PS->packCatesPapers($cates, 'is_del=0,is_del=1');
     #3.传递参数
     //dump($cates);
     $this->assign('cates', $cates);
     $this->display('index');
 }