使用Google Drive API和PHP下载文件 - Downloading a file with Google Drive API with PHP

我正在尝试制作一个系统，使我的服务器与谷歌驱动器中装满照片的文件夹保持同步（单向）。

到目前为止，我已经设法从github下载了PHP客户端库（我不使用composer），并列出了一些文件。我设法手动获得一张照片的id使用这个：

// Print the names and IDs for up to 10 files.
$optParams = array(
    'pageSize' => 10,
    'fields' => "nextPageToken, files(id, name)"
);
$results = $service->files->listFiles($optParams);
if (count($results->getFiles()) == 0) {
    print "No files found.'n";
} else {
    print "Files:'n";
    echo "<pre>";
    print_r($results);
    echo "</pre>";
}

然而，我无法从ID下载文件，以下是我尝试过的内容，但我收到一个错误，说
Fatal error: Call to undefined method Google_Service_Drive_DriveFile::getDownloadUrl()

<?php
require $_SERVER['DOCUMENT_ROOT'] . '/includes/googleAPI/vendor/autoload.php';
define('APPLICATION_NAME', 'Drive API PHP Quickstart');
define('CREDENTIALS_PATH', $_SERVER['DOCUMENT_ROOT'] . '/includes/googleAPI/drive-php-quickstart.json');
define('CLIENT_SECRET_PATH', $_SERVER['DOCUMENT_ROOT'] . '/includes/googleAPI/client_secret.json');
// If modifying these scopes, delete your previously saved credentials
// at ~/.credentials/drive-php-quickstart.json
define('SCOPES', implode(' ', array(
        "https://www.googleapis.com/auth/drive.readonly")
));
/*if (php_sapi_name() != 'cli') {
    throw new Exception('This application must be run on the command line.');
}*/
/**
 * Returns an authorized API client.
 * @return Google_Client the authorized client object
 */
function getClient()
{
    $client = new Google_Client();
    $client->setApplicationName(APPLICATION_NAME);
    $client->setScopes(SCOPES);
    $client->setAuthConfigFile(CLIENT_SECRET_PATH);
    $client->setAccessType('offline');
    // Load previously authorized credentials from a file.
    $credentialsPath = expandHomeDirectory(CREDENTIALS_PATH);
    if (file_exists($credentialsPath)) {
        $accessToken = file_get_contents($credentialsPath);
    } else {
        // Request authorization from the user.
        $authUrl = $client->createAuthUrl();
        printf("Open the following link in your browser:'n%s'n", $authUrl);
        print 'Enter verification code: ';
        $authCode = trim(fgets(STDIN));
        // Exchange authorization code for an access token.
        $accessToken = $client->authenticate($authCode);
        // Store the credentials to disk.
        if (!file_exists(dirname($credentialsPath))) {
            mkdir(dirname($credentialsPath), 0700, true);
        }
        file_put_contents($credentialsPath, json_encode($accessToken));
        printf("Credentials saved to %s'n", $credentialsPath);
    }
    $client->setAccessToken($accessToken);
    // Refresh the token if it's expired.
    if ($client->isAccessTokenExpired()) {
        $refreshToken = $client->getRefreshToken();
        $client->refreshToken($refreshToken);
        $newAccessToken = $client->getAccessToken();
        $newAccessToken['refresh_token'] = $refreshToken;
        file_put_contents($credentialsPath, json_encode($newAccessToken));
    }
    return $client;
}
/**
 * Expands the home directory alias '~' to the full path.
 * @param string $path the path to expand.
 * @return string the expanded path.
 */
function expandHomeDirectory($path)
{
    $homeDirectory = getenv('HOME');
    if (empty($homeDirectory)) {
        $homeDirectory = getenv("HOMEDRIVE") . getenv("HOMEPATH");
    }
    return str_replace('~', realpath($homeDirectory), $path);
}
/**
 * Print a file's metadata.
 *
 * @param Google_Service_Drive $service Drive API service instance.
 * @param string $fileId ID of the file to print metadata for.
 */
function printFile($service, $fileId) {
    try {
        $file = $service->files->get($fileId);
        print "Title: " . $file->getName();
        print "Description: " . $file->getDescription();
        print "MIME type: " . $file->getMimeType();
        print "Download URL: : " . $file->getDownloadUrl();
        return $file;
    } catch (Exception $e) {
        print "An error occurred: " . $e->getMessage();
    }
}
/**
 * Download a file's content.
 *
 * @param Google_Service_Drive $service Drive API service instance.
 * @param Google_Service_Drive_DriveFile $file Drive File instance.
 * @return String The file's content if successful, null otherwise.
 */
function downloadFile($service, $file) {
    $downloadUrl = $file->getDownloadUrl();
    if ($downloadUrl) {
        $request = new Google_Http_Request($downloadUrl, 'GET', null, null);
        $httpRequest = $service->getClient()->getAuth()->authenticatedRequest($request);
        if ($httpRequest->getResponseHttpCode() == 200) {
            return $httpRequest->getResponseBody();
        } else {
            // An error occurred.
            return null;
        }
    } else {
        // The file doesn't have any content stored on Drive.
        return null;
    }
}
// Get the API client and construct the service object.
$client = getClient();
$service = new Google_Service_Drive($client);

$fileId = $_GET['id'];
$file = printFile($service, $fileId);
echo "<br/><pre>";
print_r($file);
echo "</pre><hr/>";
print_r(downloadFile($service, $file));

这是printFile()的响应，正如您所看到的，应该包含链接的字段显示为空白。

我也不清楚API的v2和v3之间的区别，可能混淆了它们？它们似乎都使用相同的quickstart.php代码。

谢谢你的帮助！

对于您的问题，Drive v2和v3之间有什么区别。

以下是一些变化：

v2中的getItems()方法将在v3中变为getFiles(），并且getTitle()将变为getName()。
默认情况下不再返回全部资源。使用字段查询参数可以请求返回特定字段。如果未指定，则只返回常用字段的子集。
所有更新操作现在都使用PATCH而不是PUT
exportLinks字段已从文件中删除。要导出Google文档，请改用files.export方法。

有关更多信息，请查看此文档。

针对您在下载文件时遇到的问题。试着检查这个SO问题

据此，在获取downloadUrls时，您需要获取文件的元数据。您可以使用GET方法来完成此操作。该方法将返回一个文件资源表示形式。在该资源中，有一个downloadUrl属性。如果您已经能够访问这些文件并获得URL，那么您的身份验证设置应该没有问题。可能存在权限问题，您可能无法访问某些驱动器文件。

您也可以查看此SO问题以了解更多信息