如何使用标题php下载zip文件而不将其保存在服务器上

<?php
$files = array('includes/s.xlsx','includes/test.html');
$zipname = 'file.zip';
$zip = new ZipArchive;
$zip->open($zipname,ZipArchive::CREATE);
foreach ($files as $file) {
  $zip->addFile($file);
 }
$zip->close();


header('Content-Type: application/zip');
header('Content-disposition: attachment; filename=filename.zip');
header('Content-Length: ' . filesize($zipname));
readfile($zipname);

但我不想将zip文件保存到服务器,我只是想将它提供给用户.