$key = date(‘Y‘)."/".date(‘m‘)."/".date(‘d‘).‘/‘.substr(md5($file), 0, 5) . date(‘YmdHis‘) . rand(0, 9999) . ‘.‘ . $ext;
$key = "2020/08/05/0bfd0202008052252373349.jpg";
$file = $_FILES[‘file‘][‘tmp_name‘];
$pathinfo = pathinfo($_FILES[‘file‘][‘name‘]);
$ext = $pathinfo[‘extension‘];
原文：https://www.cnblogs.com/aln0825/p/13443382.html