Yii 框架怎么引用 JS 和 CSS 文件？

<?php
/**
 * @link http://www.yiiframework.com/
 * @license http://www.yiiframework.com/license/
 */
namespace app\assets;
use yii\web\AssetBundle;



class AppAsset extends AssetBundle
{
  public $basePath = &#39;@webroot&#39;;
  public $baseUrl = &#39;@web&#39;;
  // public $css = [
  //   &#39;css/site.css&#39;,
  //   &#39;bootstrap/css/bootstrap.min.css&#39;,
  // ];
  // public $js = [
  //   &#39;jquery/jquery.min.js&#39;,
  //   &#39;bootstrap/js/bootstrap.min.js&#39;
  // ];
  public function registerAssetFiles( $view )
  {
    //加一个版本号
    //目的：使浏览器获取最新的文件
    $release = "20200526";
    $this->css = [
      "bootstrap/css/bootstrap.min.css?v={$release}"
    ];
    $this->js = [
       &#39;jquery/jquery.min.js&#39;,
       &#39;bootstrap/js/bootstrap.min.js&#39;
    ];
    parent::registerAssetFiles( $view );
  }
}