var_dump调试程序的问题

<?php class GoodsController extends BackController{

public function addAction(){
include VIEW_PATH.'goods_add.html';
} public function insertAction(){
$model = ModelFartory::M('GoodsModel');
$data['goods_name'] = $_POST['goods_name'];
$data['shop_price'] = $_POST['shop_price'];
//$data['goods_image_ori'] = $_POST['goods_image_ori'];
$data['goods_desc'] = $_POST['goods_desc'];
$data['goods_number'] = $_POST['goods_number'];

$data['is_best'] = isset($_POST['is_best'])? '1' : '0';
$data['is_new'] = isset($_POST['is_new'])? '1' : '0';
$data['is_hot'] = isset($_POST['is_hot'])? '1' : '0';
$data['is_on_sale'] = isset($_POST['is_on_sale'])? '1' : '0';


$upload = new Upload();
$upload->setMaxsize(8*1024*1024);
$upload->setPrefix('goods_');
$upload->setUploadPath(ROOT . "upload/goods/");
$result = $upload->upload($_FILES['goods_image_ori']);
var_dump($result);
if($result){
$data['goods_image_ori'] = $result; }else{ $this->gotourl('图片上传失,失败原因：'.$upload->geterror(),'index.php?p=back&c=Goods&act=add',100);
}
@session_start();
$data['id'] = $_SESSION['admin_info']['id'];
$data['creaetime'] = time(); $result = $model->insertGoods($data);
var_dump($result);
if($result){
header('location:index.php?p=back&c=Goods&act=list');
}
} public function listAction(){
echo 'goods:list';
}

}
为什么不现实$_FILES接收的数据结构，感觉好像直接从这段代码跳过去了。