public function _initialize()
{
//获取购物车中的总商品数和总价格
$cart_model = new \Model\CartModel();
$total = $cart_model->getTotal();
$this->assign('total', $total);
//取出顶级栏目，用于导航显示
$cat_model = new \Model\CategoryModel();
$nav_list = $cat_model->getNav();
$this->assign('nav_list', $nav_list);
}
