You can let your users authenticate with Firebase using their Facebook accounts by integrating Facebook Login into your app.
Before you begin
- Add Firebase to your Android project.
- If you haven't yet connected your app to your Firebase project, do so from the Firebase console.
- Add the dependency for Firebase Authentication to your app-level
build.gradle
file:compile 'com.google.firebase:firebase-auth:9.6.1'
- On the Facebook for Developers site, get the App ID and an App Secret for your app.
- Enable Facebook Login:
- In the Firebase console, open the Auth section.
- On the Sign in method tab, enable the Facebook sign-in method and specify the App ID and App Secret you got from Facebook.
- Then, make sure your OAuth redirect URI (e.g.
my-app-12345.firebaseapp.com/__/auth/handler
) is listed as one of your OAuth redirect URIs in your Facebook app's settings page on the Facebook for Developers site in the Product Settings > Facebook Login config.
Authenticate with Firebase
- Integrate Facebook Login into your app by following the
developer's documentation. When you configure the
LoginButton
orLoginManager
object, request thepublic_profile
andemail
permissions. If you integrated Facebook Login using aLoginButton
, your sign-in activity has code similar the following:// Initialize Facebook Login button mCallbackManager = CallbackManager.Factory.create(); LoginButton loginButton = (LoginButton) findViewById(R.id.button_facebook_login); loginButton.setReadPermissions("email", "public_profile"); loginButton.registerCallback(mCallbackManager, new FacebookCallback<LoginResult>() { @Override public void onSuccess(LoginResult loginResult) { Log.d(TAG, "facebook:onSuccess:" + loginResult); handleFacebookAccessToken(loginResult.getAccessToken()); } @Override public void onCancel() { Log.d(TAG, "facebook:onCancel"); // ... } @Override public void onError(FacebookException error) { Log.d(TAG, "facebook:onError", error); // ... } });
- In your sign-in activity's
onCreate
method, get the shared instance of theFirebaseAuth
object:private FirebaseAuth mAuth; // ... // Initialize Firebase Auth mAuth = FirebaseAuth.getInstance();
- Set up an
AuthStateListener
that responds to changes in the user's sign-in state:private FirebaseAuth.AuthStateListener mAuthListener; // ... @Override protected void onCreate(Bundle savedInstanceState) { // ... mAuthListener = new FirebaseAuth.AuthStateListener() { @Override public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) { FirebaseUser user = firebaseAuth.getCurrentUser(); if (user != null) { // User is signed in Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid()); } else { // User is signed out Log.d(TAG, "onAuthStateChanged:signed_out"); } // ... } }; // ... } @Override public void onStart() { super.onStart(); mAuth.addAuthStateListener(mAuthListener); } @Override public void onStop() { super.onStop(); if (mAuthListener != null) { mAuth.removeAuthStateListener(mAuthListener); } }
- After a user successfully signs in, in the
LoginButton
'sonSuccess
callback method, get an access token for the signed-in user, exchange it for a Firebase credential, and authenticate with Firebase using the Firebase credential:private void handleFacebookAccessToken(AccessToken token) { Log.d(TAG, "handleFacebookAccessToken:" + token); AuthCredential credential = FacebookAuthProvider.getCredential(token.getToken()); mAuth.signInWithCredential(credential) .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() { @Override public void onComplete(@NonNull Task<AuthResult> task) { Log.d(TAG, "signInWithCredential:onComplete:" + task.isSuccessful()); // If sign in fails, display a message to the user. If sign in succeeds // the auth state listener will be notified and logic to handle the // signed in user can be handled in the listener. if (!task.isSuccessful()) { Log.w(TAG, "signInWithCredential", task.getException()); Toast.makeText(FacebookLoginActivity.this, "Authentication failed.", Toast.LENGTH_SHORT).show(); } // ... } }); }
If the call tosignInWithCredential
succeeds, theAuthStateListener
runs theonAuthStateChanged
callback. In the callback, you can use thegetCurrentUser
method to get the user's account data.
Next steps
After a user signs in for the first time, a new user account is created and linked to the credentials—that is, the user name and password, or auth provider information—the user signed in with. This new account is stored as part of your Firebase project, and can be used to identify a user across every app in your project, regardless of how the user signs in.
-
In your apps, you can get the user's basic profile information from the
FirebaseUser
object. See Manage Users. In your Firebase Realtime Database and Firebase Storage Security Rules, you can get the signed-in user's unique user ID from the
auth
variable, and use it to control what data a user can access.
You can allow users to sign in to your app using multiple authentication providers by linking auth provider credentials to an existing user account.
To sign out a user, call
signOut
:
FirebaseAuth.getInstance().signOut();