从谷歌云存储获取的图像在App Engine中

Question

我想在我的App Engine后端，每次得到的图像我设法得到它，我得到以下错误

com.google.api.client.googleapis.json.GoogleJsonResponseException: 503 Service Unavailable 
{ 
    "code": 503, 
    "errors": [ 
    { 
     "domain": "global", 
     "message": "java.io.IOException: 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.", 
     "reason": "backendError" 
    } 
    ], 
    "message": "java.io.IOException: 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." 
} 

现在是我的理解是，当从App Engine后端请求Application Default Credentials已足够。

应用程序默认凭证提供了一种简单的方式来获取 授权凭证以用于调用Google API。

它们最适用于呼叫需要具有相同的 身份和授权级别的独立于用户的 应用程序。这是推荐的方法，用于授权拨打 Google Cloud API，特别是在您构建部署到Google App Engine或Google Compute Engine虚拟 机器的应用程序 时。

从here

采取这是我正在尝试使用Java API

HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport(); 
GoogleCredential credential = GoogleCredential.getApplicationDefault(); 

if(credential.createScopedRequired()){ 
    credential = credential.createScoped(StorageScopes.all()); 
} 

Storage.Builder storageBuilder = new Storage.Builder(httpTransport,new JacksonFactory(),credential); 
Storage storage = storageBuilder.build(); 

Storage.Objects.Get getObject = storage.objects().get("myBucket", name); 

ByteArrayOutputStream out = new ByteArrayOutputStream(); 
      getObject.getMediaHttpDownloader().setDirectDownloadEnabled(false); 
getObject.executeMediaAndDownloadTo(out); 

byte[] oldImageData = out.toByteArray(); 
out.close(); 

ImagesService imagesService = ImagesServiceFactory.getImagesService(); 

Image oldImage = ImagesServiceFactory.makeImage(oldImageData); 
Transform resize = ImagesServiceFactory.makeResize(width, height); 

return imagesService.applyTransform(resize, oldImage); 

我只是使用证书错误得到的图像或可我不使用应用程序的默认凭据？

Answer 1

如果您想从App Engine访问您的Google Cloud Storage数据。你应该使用Google Cloud Storage Client Library

Github Project