PHP强制下载可在localhost上运行，但不能在托管服务器上运行

Question

I am trying to force download a file using following code

header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='backup.zip');
header('Content-Length: '.filesize('backup.zip') );
readfile('backup.zip');

This works totally fine on localhost (xampp) but when I uploaded to my hosting server, it just prints some weird characters on the screen like below.

PK|^EWÌV†Ÿcredit_return.csvUT ”:QT”:QTux???eK?ƒ0 ÷>‹+Ù&ßÓ ÔdÁ¢P¸“ÐB(Ê"Ñdôì÷L1ŒkŸâº¥©¾cZæi)Ïm‰©ÜÃkÞ¦Ÿ?~å0¬ r>¡?«Ù°(…Ð說[Ó¯Pt«: B]ñE3ºKª¯ª ÷G…»êJKs‚B³ÓsšX v/qÊ™T%ØIƒ=°½mÑ°Cß–cÊÀ~ßM”r—ÒJ_hɼÑ?PK|^EÑàÀUäv?txn_type.csvUT ”:QT”:QTux???]'KOB1?…÷üŠ¬jBñYÂÂ'¸$Mï½3dnAø÷V!qŽ»v¾³8râu9ïiZW®o?ý~6Y¾Ü¡'tàÝpvª°§æ¦Y?“†…¤Ê'¾bD§®Ûл* MŸú/Ï?ðñöb¾¶æ?¼o0P'ºÁ_K³‡‹äÒ« ;kayRÂbUÔ»Ëu–F5‚^?‚Bóê?½œÿB4-pÄÀ¢'¡C çëññ/PK|^E ~ìa3; user.csvUT ”:QT”:QTux???+-N-ŠÏLÑÉKÌMÕ)rÀŒ‚Äââòü¢.CÇ”òÄÌD(eibdlhbbdbÄPK|^EeHÐ'åû?definitions.sqlUT ”:QT”:QTux???¥ÕOo‚0ð»É

I did lot of search on google, stackoverflow itself has many questions regarding this but most are unanswered or not satisfacorily answered.

Hint: This may be related to output buffer.

Answer 1

The weird characters start with "PK", so i think you are looking at the contents of backup.zip (remember PKZIP). Your browser does not seem to know what to do with it.

There is an example provided by php: http://php.net/manual/en/function.readfile.php which has more header-stuff. might do the trick.

The header that declares it as an attachment does not have the quotes right in your example. You could use double quotes around to filename and an extra single quote after the filename to make the quoting "correct".

header('Content-Disposition: attachment; filename="backup.zip"');

Because of the incorrect quotes, the entire header may not be in effect.

Answer 2

Try the following.

header('Content-Type: application/octet-stream');
header("Content-Disposition: attachment; filename='backup.zip'");
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($file));
ob_clean();
flush();
readfile('backup.zip');