利用 PHP 代码强制下载文件的类型，有时需要一些文件不能在线打开，而是执行后需要下载，这时就用这个函数就可以解决了
function downloadFile($file){
/*Coded by Alessio Delmonti*/
$file_name = $file;
$mime = 'application/force-download';
header('Pragma: public'); // required
header('Expires: 0'); // no cache
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Cache-Control: private',false);
header('Content-Type: '.$mime);
header('Content-Disposition: attachment; filename="'.basename($file_name).'"');
header('Content-Transfer-Encoding: binary');
header('Connection: close');
readfile($file_name); // push it out
exit();
}