php 图片，文件下载

//  文件下载
   public function download()
   {
      $url = $_GET['url'];
      if($url!='0') {
         $filename = $url;
         $fileinfo = pathinfo($filename);
         header('Content-type: application/x-' . $fileinfo['extension']);
         header('Content-Disposition: attachment; filename=' . $fileinfo['basename']);
         readfile($filename);
         exit();
      }
   }