Firebase Phone Authentication In Android

Introduction

1. Firebase User Authentication In Android - Part One
2. Firebase User Authentication In Android - Part Two

Firebase Phone Authentication

Firebase Setup

• Step 1: Creating a New Project with Empty Activity.
• Step 2: Setting up the Firebase Library.
• Step 3: Implementation of Firebase Phone Authentication.

1. Open Android Studio and select Create a new project.
2. Name the project as you wish and select your activity template.
   
3. Click the “Finish” button to create a new project in Android Studio.

1. Open your project level build.gradle file and add the following lines in dependencies
   1. {
   2. …
   3. classpath 'com.google.gms:google-services:3.1.0'
   4. …
   5. }

2. Then add the following lines in all projects in the project level build.gradle file.
   1. allprojects {
   2. repositories {
   3. google()
   4. jcenter()
   5. maven {
   6. url "https://maven.google.com"
   7. }
   8. }
   9. }

3. Then add the following lines in app level build.gradle file to apply google services to your project.
   1. dependencies {
   2. ...
   3. implementation 'com.google.firebase:firebase-auth:11.8.0'
   4. }
   5. apply plugin: 'com.google.gms.google-services'

4. Then click “Sync Now” to setup your project.

• send verification code
• validates verification success & failure
• manage sign-in & sign-out from the application

• To verify the user’s phone number, we have to prompt users to enter the phone number.
• Then send the phone number to firebase and request to validate the user’s phone number.
• It is achieved by PhoneAuthProvider as shown in the following code snippet.
  1. PhoneAuthProvider.getInstance().verifyPhoneNumber(
  2. phoneNumber, // Phone number to verify
  3. 60, // Timeout duration
  4. TimeUnit.SECONDS, // Unit of timeout
  5. this, // Activity (for callback binding)
  6. mCallbacks); // OnVerificationStateChangedCallbacks

• mCallbacks are used to know the verification status and the callback method is implemented as in the following.
  1. mCallbacks = new PhoneAuthProvider.OnVerificationStateChangedCallbacks() {
  2. @Override
  3. public void onVerificationCompleted(PhoneAuthCredential credential) {
  4. Log.d(TAG, "onVerificationCompleted:" + credential);
  5. signInWithPhoneAuthCredential(credential);
  6. }
  8. @Override
  9. public void onVerificationFailed(FirebaseException e) {
  10. Log.w(TAG, "onVerificationFailed", e);
  11. if (e instanceof FirebaseAuthInvalidCredentialsException) {
  12. mPhoneNumberField.setError("Invalid phone number.");
  13. } else if (e instanceof FirebaseTooManyRequestsException) {
  14. Snackbar.make(findViewById(android.R.id.content), "Quota exceeded.",
  15. Snackbar.LENGTH_SHORT).show();
  16. }
  17. }
  19. @Override
  20. public void onCodeSent(String verificationId,
  21. PhoneAuthProvider.ForceResendingToken token) {
  22. Log.d(TAG, "onCodeSent:" + verificationId);
  23. mVerificationId = verificationId;
  24. mResendToken = token;
  25. }
  26. };

• Here,
  • onVerificationCompleted(PhoneAuthCredential)
    This method is called when the user number verified successfully.
  • onVerificationFailed(FirebaseException)
    This method is called when an error occurred during verification.
  • onCodeSent(String verification, PhoneAuthProvider.ForceResendingToken)
    This method is called when the verification code is sent to the user via SMS.

• Phone Authentication Credentials can be read from PhoneAuthProvider as shown in the following snippets.
  1. PhoneAuthCredential credential = PhoneAuthProvider.getCredential(verificationId, code);
  2. // verificationId can be found in onCodeSent function in callback functionality
  3. // code is retrieved from SMS send by Firebase

• The retrieved credentials are used to sign in to the application. It can be achieved by the following snippet.
  1. mAuth.signInWithCredential(credential)
  2. .addOnCompleteListener(this, new OnCompleteListener() {
  3. @Override
  4. public void onComplete(@NonNull Task task) {
  5. if (task.isSuccessful()) {
  6. Log.d(TAG, "signInWithCredential:success");
  7. FirebaseUser user = task.getResult().getUser();
  8. startActivity(new Intent(PhoneAuthActivity.this, MainActivity.class));
  9. finish();
  10. } else {
  11. Log.w(TAG, "signInWithCredential:failure", task.getException());
  12. if (task.getException() instanceof FirebaseAuthInvalidCredentialsException) {
  13. mVerificationField.setError("Invalid code.");
  14. }
  15. }
  16. }
  17. });