Firebase - Google Sign-In Authentication

Firebase: Google Sign-In Authentication

Firebase: Google Sign-in Authentication

Google Sign-in Authentication. It is pretty easy to do.

Starting steps are the same as we have done with other authentication methods, which are as follows:

Creating an Android project.
Creating a Firebase project.
Adding Firebase to the Android project or application, either manually or Firebase Assistance.
Adding the required libraries and JSON files.

Step 1:

Apart from firebase auth and core libraries, we have to add google play services auth in app.gradle file

Step 2:

In the next step, we have to enable the Google sign-in method in Firebase console. We also have to add a project supporting email.

Step 3:

Just like our previous method, we have to set SHA-1 and SHA-256 keys.

Step 4:

In the next step, we will create the layout file that contains three buttons Google sign-in, sign-out, and sign-out and disconnect. The activity layout will look like:

Step 5:

Now, we will modify our MainActivity.java file to perform the Google sign-in authentication in the following way:

//Implement OnClickListener for sign-in button

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

```
   
```

    //Adding tag for logging and RC_SIGN_IN for an activity result

private static final String TAG = "GoogleActivity";

private static final int RC_SIGN_IN = 9001;

```
   
```
```
    // Adding Google sign-in client  
```

    GoogleSignInClient mGoogleSignInClient;

```
   
```

    //Creating member variable for FirebaseAuth

```
private FirebaseAuth mAuth;  
```
```
   
```
```
    @Override  
```

protected void onCreate(Bundle savedInstanceState) {

```
super.onCreate(savedInstanceState);  
```

        setContentView(R.layout.activity_main);

```
   
```

        //Adding buttons to the OnClickListener

        findViewById(R.id.sign_in_button).setOnClickListener(this);

        findViewById(R.id.signOutButton).setOnClickListener(this);

        findViewById(R.id.disconnectButton).setOnClickListener(this);

```
   
```

        //Building Google sign-in and sign-up option.

```
// Configuring Google Sign In  
```

GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)

// for the requestIdToken, use getString(R.string.default_web_client_id), this is in the values.xml file that

                // is generated from your google-services.json file (data from your firebase project), uses the google-sign-in method

```
                // web api key  
```

.requestIdToken(getString(R.string.default_web_client_id))//Default_web_client_id will be matched with the

```
                .requestEmail()  
```
```
                .build();  
```
```
   
```

// Build a GoogleSignInClient with the options specified by gso.

mGoogleSignInClient = GoogleSignIn.getClient(this, gso);

```
   
```

// Set the dimensions of the sign-in button.

SignInButton signInButton = findViewById(R.id.sign_in_button);

        signInButton.setSize(SignInButton.SIZE_WIDE);

```
   
```
```
// Initialize Firebase Auth  
```
```
mAuth = FirebaseAuth.getInstance();  
```
```
    }  
```
```
     //Creating onStart() method.  
```
```
    @Override  
```
```
public void onStart() {  
```
```
super.onStart();  
```
```
   
```

// Checking if the user is signed in (non-null) and update UI accordingly.

FirebaseUser currentUser = mAuth.getCurrentUser();

```
   
```
```
if (currentUser != null) {  
```

            Log.d(TAG, "Currently Signed in: " + currentUser.getEmail());

            Toast.makeText(MainActivity.this, "Currently Logged in: " + currentUser.getEmail(), Toast.LENGTH_LONG).show();

```
        }  
```
```
    }  
```

     //Calling onActivityResult to use the information about the sign-in user contains in the object.

```
    @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) {  
```

            Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);

```
try {  
```

// Google Sign In was successful, authenticate with Firebase

GoogleSignInAccount account = task.getResult(ApiException.class);

                Toast.makeText(this, "Google Sign in Succeeded",  Toast.LENGTH_LONG).show();

                firebaseAuthWithGoogle(account);

            } catch (ApiException e) {

// Google Sign In failed, update UI appropriately

Log.w(TAG, "Google sign in failed", e);

                Toast.makeText(this, "Google Sign in Failed " + e,  Toast.LENGTH_LONG).show();

```
            }  
```
```
        }  
```
```
    }  
```

    //Creating helper method FirebaseAuthWithGoogle().

private void firebaseAuthWithGoogle(GoogleSignInAccount acct) {

        Log.d(TAG, "firebaseAuthWithGoogle:" + acct.getId());

        //Calling get credential from the oogleAuthProviderG

        AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null);

mAuth.signInWithCredential(credential)

                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {

//Override th onComplete() to see we are successful or not.

```
 @Override  
```

public void onComplete(@NonNull Task<AuthResult> task) {

```
if (task.isSuccessful()) {  
```

// Update UI with the sign-in user's information

FirebaseUser user = mAuth.getCurrentUser();

                            Log.d(TAG, "signInWithCredential:success: currentUser: " + user.getEmail());

                            Toast.makeText(MainActivity.this, "Firebase Authentication Succeeded ",  Toast.LENGTH_LONG).show();

```
                        } else {  
```

// If sign-in fails to display a message to the user.

Log.w(TAG, "signInWithCredential:failure", task.getException());

                            Toast.makeText(MainActivity.this, "Firebase Authentication failed:" + task.getException(),  Toast.LENGTH_LONG).show();

```
                        }  
```
```
                    }  
```
```
                });  
```
```
    }  
```
```
   
```
```
public void signInToGoogle(){  
```

        //Calling Intent and call startActivityForResult() method

        Intent signInIntent = mGoogleSignInClient.getSignInIntent();

        startActivityForResult(signInIntent, RC_SIGN_IN);

```
    }  
```
```
   
```
```
private void signOut() {  
```
```
// Firebase sign out  
```
```
FirebaseAuth.getInstance().signOut();  
```
```
   
```
```
// Google sign out  
```

mGoogleSignInClient.signOut().addOnCompleteListener(this,

```
new OnCompleteListener<Void>() {  
```
```
                    @Override  
```

public void onComplete(@NonNull Task<Void> task) {

// Google Sign In failed, update UI appropriately

Toast.makeText(getApplicationContext(),"Signed out of google",Toast.LENGTH_SHORT).show();

```
                    }  
```
```
                });  
```
```
    }  
```
```
   
```
```
private void revokeAccess() {  
```
```
// Firebase sign out  
```
```
FirebaseAuth.getInstance().signOut();  
```
```
   
```
```
// Google revoke access  
```

mGoogleSignInClient.revokeAccess().addOnCompleteListener(this,

```
new OnCompleteListener<Void>() {  
```
```
                    @Override  
```

public void onComplete(@NonNull Task<Void> task) {

// Google Sign In failed, update UI appropriately

```
Log.w(TAG, "Revoked Access");  
```
```
                    }  
```
```
                });  
```
```
    }  
```
```
   
```
```
    @Override  
```
```
public void onClick(View v) {  
```
```
int i = v.getId();  
```
```
if (i == R.id.sign_in_button) {  
```
```
Adding signInToGoogle() method  
```
```
 signInToGoogle();  
```
```
        }  
```
```
else if (i == R.id.signOutButton) {  
```
```
            signOut();  
```
```
        }  
```

else if (i == R.id.disconnectButton) {

```
            revokeAccess();  
```
```
        }  
```
```
    }  
```
```
   
```
```
    @Override  
```

public void onPointerCaptureChanged(boolean hasCapture) {

```
   
```
```
    }  
```
```
}  
```

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