yii2怎么引入css和js文件

<?php use yii\helpers\Html;?><?=Html::cssFile('@web/css/index.css')?><?=Html::jsFile('@web/js/jquery.min.js')?>

<script src="js/nav.js"></script>

<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */
 namespace app\assets; 
use yii\web\AssetBundle; 
/**
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
 class AppAsset extends AssetBundle{
     public $basePath = '@webroot';    
     public $baseUrl = '@web';    
     public $css = [        
     'css/site.css',        
     'css/base.css'
    ];    
    public $js = [        
    'js/sliders.js'
    ];    
    public $depends = [ //依赖包，没有可以不写
        'yii\web\YiiAsset',        
        'yii\bootstrap\BootstrapAsset',  
    ]; 
    //定义按需加载JS方法，注意加载顺序在最后  
    public static function addScript($view, $jsfile) {  
        $view->registerJsFile($jsfile, [AppAsset::className(), 'depends' => 'api\assets\AppAsset']);  
    }  
      
   //定义按需加载css方法，注意加载顺序在最后  
    public static function addCss($view, $cssfile) {  
        $view->registerCssFile($cssfile, [AppAsset::className(), 'depends' => 'api\assets\AppAsset']);  
    }  
}

<?php
use yii\helpers\Html;use app\assets\AppAsset;
AppAsset::register($this); 
?>

<?php$this->beginPage() ?> 
<?php $this->head() ?>
<?php $this->beginBody() ?> 
<?php $this->endBody() ?>
<?php $this->endPage() ?>

AppAsset::register($this);  
//css定义一样  
$this->registerCssFile('@web/css/font-awesome.min.css',['depends'=>['api\assets\AppAsset']]);  
  
 $this->registerJsFile('@web/js/jquery-ui.custom.min.js',['depends'=>['api\assets\AppAsset']]);  
//$this->registerJsFile('@web/js/jquery-ui.custom.min.js',['depends'=>['api\assets\AppAsset'],
'position'=>$this::POS_HEAD]);