You can let your users authenticate with Firebase using their Google Accounts by integrating Google Sign-In into your app.
Before you begin
- Add Firebase to your Android project.
- Add the dependencies for Firebase Authentication and Google Sign-In to your
app-level
build.gradle
file:compile 'com.google.firebase:firebase-auth:9.6.1' compile 'com.google.android.gms:play-services-auth:9.6.1'
- If you haven't yet connected your app to your Firebase project, do so from the Firebase console.
- If you haven't yet specified your app's SHA-1 fingerprint, do so from the Authenticating Your Client for details on how to get your app's SHA-1 fingerprint.
- Enable Google Sign-In in the Firebase console:
- In the Firebase console, open the Auth section.
- On the Sign in method tab, enable the Google sign-in method and click Save.
Authenticate with Firebase
- Integrate Google Sign-In into your app by following the steps on the
Integrating Google Sign-In into
Your Android App page.
When you configure the
GoogleSignInOptions
object, callrequestIdToken
:// Configure Google Sign In GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN) .requestIdToken(getString(R.string.default_web_client_id)) .requestEmail() .build();
You must pass your server's client ID to therequestIdToken
method. To find the OAuth 2.0 client ID:- Open the Credentials page in the API Console.
- The Web application type client ID is your backend server's OAuth 2.0 client ID.
private void signIn() { Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient); startActivityForResult(signInIntent, RC_SIGN_IN); } @Override public void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...); if (requestCode == RC_SIGN_IN) { GoogleSignInResult result = Auth.GoogleSignInApi.getSignInResultFromIntent(data); if (result.isSuccess()) { // Google Sign In was successful, authenticate with Firebase GoogleSignInAccount account = result.getSignInAccount(); firebaseAuthWithGoogle(account); } else { // Google Sign In failed, update UI appropriately // ... } } }
- In your sign-in activity's
onCreate
method, get the shared instance of theFirebaseAuth
object:private FirebaseAuth mAuth; // ... 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, get an ID token from the
GoogleSignInAccount
object, exchange it for a Firebase credential, and authenticate with Firebase using the Firebase credential:private void firebaseAuthWithGoogle(GoogleSignInAccount acct) { Log.d(TAG, "firebaseAuthWithGoogle:" + acct.getId()); AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null); 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(GoogleSignInActivity.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();