求助各位大神
header("content-type:text/html;charset=utf-8");

$upload = new \Think\Upload();

$upload->maxSize = 200000 ;
$upload->allowExts = array(
'jpg', 'gif', 'png', 'jpeg','txt','mp4'
);

$upload->savePath = 'Public/thumb/';

$upload->replace = true;
$upload->autoSub = true;
$info = $upload->upload();
var_dump($info);exit;