Firebase身份验证有效，但使用Google Text to Speech API时出现错误

我已经建立了一个小型的android和firebase应用程序...身份验证就像一个超级按钮，在firebase控制台中，我可以看到使用Google帐户登录的用户.

I've set up a small android and firebase app... Authentification works like a charm, and in the firebase console, I can see my user, logged in with the Google account.

现在，我正在尝试使用文字转语音" api进行一些实验，并按照此教程进行操作:

Now I am trying to experiment a little with the Text to Speech api, and in doing so, I followed this tutorial:

https://github.com/GoogleCloudPlatform /java-docs-samples/tree/master/texttospeech/cloud-client

通过设置GOOGLE_APPLICATION_CREDENTIALS环境变量，我设法使小型Java应用程序正常工作(我按照本教程的步骤进行操作:

I managed to make the small java app work, by setting the GOOGLE_APPLICATION_CREDENTIALS Environment variable (I followed this tutorial for this step: https://cloud.google.com/docs/authentication/getting-started), but I am not sure what I need to do to make that code work in the Android app where the users are authentificated..

尝试调用TextToSpeech API时遇到的错误是:

The Error that I get when trying to make a call to the TextToSpeech API is:

应用程序默认凭据不可用.他们是 如果在Google Compute Engine中运行，则可用.否则， 必须定义环境变量GOOGLE_APPLICATION_CREDENTIALS 指向定义凭据的文件.看 https://developers.google.com/accounts/docs/application-default-凭据 有关更多信息.

The Application Default Credentials are not available. They are available if running in Google Compute Engine. Otherwise, the environment variable GOOGLE_APPLICATION_CREDENTIALS must be defined pointing to a file defining the credentials. See https://developers.google.com/accounts/docs/application-default-credentials for more information.

提到的错误来自以下行:

The error mentioned comes from the line:

TextToSpeechClient textToSpeechClient = TextToSpeechClient.create();

出现此错误的原因是，在android模拟器上，我无权访问在操作系统中设置为环境变量的凭据.因此，我必须以另一种方式提供凭据.

This error appears because of the fact that on the android emulator I don't have access to the credentials that are set as environment variable in my OS..So I have to provide the credentials in another way.

对于其他Google API(例如存储)，我发现可以这样做:

In the case of other Google APIs, like Storage, I found out that this can be done like this:

// You can specify a credential file by providing a path to GoogleCredentials.
// Otherwise credentials are read from the GOOGLE_APPLICATION_CREDENTIALS environment variable.
GoogleCredentials credentials = GoogleCredentials.fromStream(new FileInputStream(jsonPath))
 .createScoped(Lists.newArrayList("https://www.googleapis.com/auth/cloud-platform"));
Storage storage = StorageOptions.newBuilder().setCredentials(credentials).build().getService();

我设法用json文件的内容创建了GoogleCredentials对象，但是TextToSpeech客户端似乎没有提供类似于以下功能:

I managed to create the GoogleCredentials object with the contents of the json file, however the TextToSpeech client doesn't seem to provide a functionality similar to this:

StorageOptions.newBuilder().setCredentials(credentials).build()

所以我的问题是....是否可以将凭据对象提供给TextToSpeech客户端?

So my question is....is there a way to provide the Credentials object to the TextToSpeech client?

谢谢