CMultiFileUpload

protected function getClientOptions()
{
    $options=$this->options;
    foreach(array('onFileRemove','afterFileRemove','onFileAppend','afterFileAppend','onFileSelect','afterFileSelect') as $event)
    {
        if(isset($options[$event]) && !($options[$event] instanceof CJavaScriptExpression))
            $options[$event]=new CJavaScriptExpression($options[$event]);
    }

    if($this->accept!==null)
        $options['accept']=$this->accept;
    if($this->max>0)
        $options['max']=$this->max;

    $messages=array();
    foreach(array('remove','denied','selected','duplicate','file') as $messageName)
    {
        if($this->$messageName!==null)
            $messages[$messageName]=$this->$messageName;
    }
    if($messages!==array())
        $options['STRING']=$messages;

    return $options;
}

public function registerClientScript()
{
    $id=$this->htmlOptions['id'];

    $options=$this->getClientOptions();
    $options=$options===array()? '' : CJavaScript::encode($options);

    $cs=Yii::app()->getClientScript();
    $cs->registerCoreScript('multifile');
    $cs->registerScript('Yii.CMultiFileUpload#'.$id,"jQuery(\"#{$id}\").MultiFile({$options});");
}

public function run()
{
    list($name,$id)=$this->resolveNameID();
    if(substr($name,-2)!=='[]')
        $name.='[]';
    if(isset($this->htmlOptions['id']))
        $id=$this->htmlOptions['id'];
    else
        $this->htmlOptions['id']=$id;
    $this->registerClientScript();
    echo CHtml::fileField($name,'',$this->htmlOptions);
}