方法一：
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.basename($filepath));
header('Content-Transfer-Encoding: binary');
header('Expires: 0′);
header('Cache-Control: must-revalidate, post-check=0, pre-check=0′);
header('Pragma: public');
header('Content-Length: ' . filesize($filepath));
readfile($file_path);
方法二：
$fileinfo = pathinfo($filename);
header('Content-type: application/x-'.$fileinfo['extension']);
header('Content-Disposition: attachment; filename='.$fileinfo['basename']);
header('Content-Length: '.filesize($filename));
readfile($thefile);
exit();
