ThinkPHP框架下如何用PHP自帶的ZipArchive類打包壓縮文件

public function downloadzip(){
    $catid = $this->request->param('catid/d', 0);
    $id = $this->request->param('id/d', 0);
    $category = getCategory($catid);
    if (empty($category)) {
        $this->error('該欄目不存在！');
    }
        $modelid = $category['modelid'];
        $fieldList = $this->Cms_Model->getFieldList($modelid, $id);

    $attatchs=$fieldList['uploadmaterial']['value'];

    $attatchsarray=explode(',',$attatchs);
    $zip=new \ZipArchive();
    $downpath=[];
    $timefils=date("Ymd",time());
    if(!file_exists('uploads/zip/'.$timefils)){
        mkdir ('uploads/zip/'.$timefils,0777,true);
    }

    $zipName ='uploads/zip/'.$timefils.'/download'.$id.'.zip';

    if($zip->open($zipName,\ZipArchive::OVERWRITE | \ZipArchive::CREATE)==TRUE){
        foreach($attatchsarray as $key=>$value){
            $downpath=dirname(ROOT_PATH).get_file_path($value);
            $downpathname=get_file_name($value); //改文件一定得為本地地址不可以為域名地址
                $zip->addFile($downpath, basename($downpathname));  //basename($downpathname)這個是壓縮包里面的文件名稱

        }
    }
    $zip->close();

    if(!file_exists($zipName)){
        $this->error('文件創建失敗');
    }
    header('Content-Type: application/zip');
    header('Content-disposition: attachment; filename='.$zipName);
    header('Content-Length: ' . filesize($zipName));//文件大小
    readfile($zipName);
}