Am I getting the steps right for verifying a user's Android in-app subscription?

Question

I am making an app that does not require a user account/login, and allows the user to purchase a subscription. I want to use the Google Play Developer API to verify whether

Answer 1

I don't know in 2012, but in 2015 you should not do any of these steps manually. I had a very hard time to find the documentation so I am posting here in case it helps anyone.

1. You should only query in-app purchases from your server for security reasons as otherwise you can trust none of the 2 ends of the purchase process.

Now on the server side (I think you could still use the same code from your app if you absolutely need to), include the google-api-services-androidpublisher client library to your project (see https://developers.google.com/api-client-library/java/apis/androidpublisher/v1)

As you mentioned, you need a service account with a P12 file (the client library only accept P12 file).

Then the following code will authenticate and get purchase information nicely:

    HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
    JsonFactory jsonFactory = new JacksonFactory();

    List<String> scopes = new ArrayList<String>();
    scopes.add(AndroidPublisherScopes.ANDROIDPUBLISHER);

    Credential credential = new GoogleCredential.Builder().setTransport(httpTransport).setJsonFactory(jsonFactory)
            .setServiceAccountId(googleServiceAccountId)
            .setServiceAccountPrivateKeyFromP12File(new File(googleServicePrivateKeyPath))
            .setServiceAccountScopes(scopes).build();
    AndroidPublisher publisher = new AndroidPublisher.Builder(httpTransport, jsonFactory, credential).build();
    AndroidPublisher.Purchases purchases = publisher.purchases();
    final Get request = purchases.get(packageName, productId, token);
    final SubscriptionPurchase purchase = request.execute();

    // Do whatever you want with the purchase bean

Information on Java client authentication can be found here: https://developers.google.com/identity/protocols/OAuth2ServiceAccount