php 强制文件下载

$filename='veno_license.txt';
header("Content-Type: application/force-download");
header("Content-Disposition: attachment; filename=".basename($filename)); 
echo "||";

实现流文件下载

header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.basename($filename));
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');
header('Content-Length: ' . filesize($filename));
ob_clean();
flush();
readfile($filename);
exit;