上传的图片没有设置为公开的谷歌云存储-谷歌应用引擎

我遇到了一个问题。我确实遵循了谷歌应用引擎的两个答案——上传的文件在谷歌云存储上不是公开的，但仍然没有运气。当图像上传到bucket

这是我的代码:

// Google API to create an absolute URL that can be used by a user to asynchronously upload a large blob
require_once 'google/appengine/api/cloud_storage/CloudStorageTools.php';
use google'appengine'api'cloud_storage'CloudStorageTools;
// The name of cloud storage bucket
$options = [ 'gs_bucket_name' => 'example_images' ];
$upload_url = CloudStorageTools::createUploadUrl('/test.php', $options);
$fileName = 'gs://example_images/'.$_FILES['file']['name'];
echo $fileName."'n";
$options = array('gs'=>array('acl'=>'public-read','Content-Type' => $_FILES['file']['type']));
$ctx = stream_context_create($options);
if (false == rename($_FILES['file']['tmp_name'], $fileName, $ctx)) {
    die('Could not rename.');
}
$object_public_url = CloudStorageTools::getPublicUrl($fileName, false);
print("Successfull! ");

我做错了什么?