yii怎么引用assets？

$assets = Yii::getPathOfAlias('ext').'/css'; 
//$baseUrl = Yii::app()->getAssetManager()->publish($assets); 
$baseUrl = Yii::app()->assetManager->publish($assets);  //extensions/css发布到assets的创建一个随机不冲突的文件夹下 
Yii::app()->clientScript->registerCssFile($baseUrl.'/main.css');//引用assets下面的main.css

<?php 
class AdminModule extends CWebModule 
{ 
    private $_assetsUrl; 
   
    public function getAssetsUrl() 
    { 
        if($this->_assetsUrl===null) 
            $this->_assetsUrl=Yii::app()->getAssetManager()->publish(Yii::getPathOfAlias(&#39;application.modules.admin.assets&#39;)); 
        return $this->_assetsUrl; 
    } 
   
    public function setAssetsUrl($value) 
    { 
        $this->_assetsUrl=$value; 
    } 
}

<link rel="stylesheet" type="text/css" href="<?php echo $this->module->assetsUrl; ?>/css/screen.css"/>

 $baseJsUrl = Yii::app()->getAssetManager()->publish($baseJsPath, false, -1, YII_DEBUG);