public function add()
 {
     if (IS_POST) {
         $model = new \Model\RoleModel();
         if ($data = $model->create(I('post.'), 1)) {
             if ($model->add($data)) {
                 $this->success('添加角色成功', U('showlist'), 1);
                 exit;
             }
             $this->error('添加角色失败');
         }
         $this->error($model->getError());
     }
     //获取所有的权限
     $priv_model = new \Model\PrivilegeModel();
     $priv_list = $priv_model->getTree();
     $this->assign('priv_list', $priv_list);
     $this->display();
 }