Cloud-Based App Example

This is a sample app which shows:

how to make an app decoupled by its backend, thanks to a BackendAdapter interface;
and how to integrate the most common social media authentication providers, like Facebook, Twitter and Google, via the Social Auth library.

For the sake of this example I have implemented the backend in Firebase, partially using as inspiration the Udacity's course "Firebase Essentials For Android" by Google.

Motivations

Read the motivations about this project on my blog posts [part 1] (http://antoniocappiello.com/2016/02/12/getting-started-with-firebase-while-moving-away-from-parse/) and part 2.

Instructions to build the project

The app's build.gradle file uses three variables to connect to your firebase app. Those variables are not included in the git repo for security reasons, therefore you need to create a gradle.properties file in the root folder of the project with the following variables:

FirebaseRootUrl = "https://[YOUR FIREBASE APP NAME AS IN THE DASHBORAD].firebaseio.com/"
FirebaseTestEmail = "[yourtestmail@mail.com]"
FirebaseTestPw = "[yourtestpw]"

The FirebaseTestEmail and FirebaseTestPw are used only to facilitate the login to Firebase with a known account and to avoid to fill in the username and password. Those two variables are used only in the dev product flavor.

Social Authentication service (libray)

To facilitate the authentication flow with Facebook, Twitter, and Google, this cloud-based-app sample uses the Social Auth library. This library is open-source and is partially inspired on the Firebase-UI library. The Firebase-UI library provides login to social media only via a predefined pop-up dialog and it doesn't help to transfer the authentication information and the current firebase ref from one activity to another of our app (in case we are building a multi-activity app). The Social Auth library, instead, allows you to use your custom UI to login to social media, and it is decoupled from your backend implementation thanks to the BackendAdapter interface. For example, if you decide to use Firebase as your backend, you can create a FirebaseBackend class which extends the BackendAdapter and which is available in your whole app, by removing the need to transfer refs and auth information among activities. For more information, see the could-based-app example of this repo.

Usage

The Social Auth library is available on jCenter, therefore, it could easily be imported into your app with the following dependency:

  compile 'com.antoniocappiello.library:socialauth:0.0.1'

To start using it, just create a new instance and add one or more social media provider:

  mAuthService = new AuthService()
                  .enableAuthProvider(googleAuthProvider)
                  .enableAuthProvider(facebookAuthProvider)
                  .enableAuthProvider(twitterAuthProvider);

You can create social media provider in this way:

  /**
   * Create TWITTER Authentication Provider
   */
  OAuthTokenHandler twitterOAuthTokenHandler = new OAuthTokenHandler(AuthProviderType.TWITTER, mBackendAdapter);

  AuthProvider twitterAuthProvider = new TwitterAuthProvider.Builder()
          .activity(this)
          .signInView(mButtonSignInWithTwitter)
          .oAuthTokenHandler(twitterOAuthTokenHandler)
          .build();

  /**
   * Create FACEBOOK Authentication Provider
   */
  OAuthTokenHandler facebookOAuthTokenHandler = new OAuthTokenHandler(AuthProviderType.FACEBOOK, mBackendAdapter);

  AuthProvider facebookAuthProvider = new FacebookAuthProvider.Builder()
          .activity(this)
          .signInView(mButtonSignInWithFacebook)
          .oAuthTokenHandler(facebookOAuthTokenHandler)
          .build();

  /**
   * Create GOOGLE Authentication Provider
   */
  OAuthTokenHandler googleOAuthTokenHandler = new OAuthTokenHandler(AuthProviderType.GOOGLE, mBackendAdapter);
  GoogleApiClient.ConnectionCallbacks googleConnectionCallback = getGoogleConnectionCallback();
  GoogleApiClient.OnConnectionFailedListener googleOnConnectionFailedListener = getGoogleOnConnectionFailedListener();

  AuthProvider googleAuthProvider = new GoogleAuthProvider.Builder()
          .activity(this)
          .signInView(mButtonSignInWithGoogle)
          .oAuthTokenHandler(googleOAuthTokenHandler)
          .connectionCallback(googleConnectionCallback)
          .onConnectionFailedListener(googleOnConnectionFailedListener)
          .build();

As you can see, each authentication provider can be built with a View on which will be automatically associated the "Sign In" action.

When the authentication with the specific provider is completed successfully, one of the methods of the BackendAdapter interface will be invoked. You can use them to trigger UI changes because the user are logged in, or you can add a further step of authentication by using the returned token, in case your backend needs it (like in this sample project where it is used to automatically authenticate to Firebase).

LogIn via Facebook and Twitter

In order to use authentication via social media, create under res/values a file named keys.xml (it is already in .gitignore) and add to it the following lines with your data:

<string name="facebook_app_id">[VALUE]</string>
<string name="twitter_app_key">[VALUE]</string>
<string name="twitter_app_secret">[VALUE]</string>

Moreover, for Facebook you need also to configure your app in your Facebook Dev page, as explained here (don't forget to add your app keyhash, which you can generate with the method service/utils/LogHelper.logHashKey()).

For Twitter, follow those instructions.

LogIn via Google

If you're using Google authentication, you need to create a google project in your developer portal by following those instructions and then place your google-services.json in the app folder.