public function img_url()
{
$id = request()->param('id', 1122);
$info = Db::name('attachment')->where(array('id' => $id))->find(); if ($info['drawing']) {
$filename = substr($info['drawing'],1);
} else {
$filename = substr($info['url'],1);
}
Header("Content-type: application/octet-stream");
Header("Accept-Ranges: bytes");
Header("Accept-Length: " . filesize($filename));
Header("Content-Disposition: attachment; filename=" . basename($filename));
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');
echo file_get_contents($filename);
exit();
}