如何用Google Drive API在PHP中对foreach进行json编码

composer require google/apiclient:^2.0

require_once 'vendor/autoload.php';

$client = new Google_Client();
$client->setAuthConfig('path/to/client_secret.json');
$client->addScope(Google_Service_Drive::DRIVE);
$service = new Google_Service_Drive($client);

$accessToken = $client->fetchAccessTokenWithAssertion();
$client->setAccessToken($accessToken);

$files = $service->files->listFiles();
$fileList = array();
foreach ($files->getFiles() as $file) {
    $fileList[] = array(
        'name' => $file->getName(),
        'id' => $file->getId(),
        'mimeType' => $file->getMimeType(),
        'webViewLink' => $file->getWebViewLink()
    );
}

$jsonData = json_encode($fileList);
echo $jsonData;