ANDROID STUDIO / 구글 로그인 만들기 / 2

이번에는 구글 API를 이용하여 로그인 하는 앱을 만들 것이다.

구글 API 이용하는 법(안드로이드 기준)

https://firebase.google.com/docs/auth/android/google-signin?hl=ko#kotlin+ktx

Android에서 Google로 인증  |  Firebase Authentication

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전체 코드

 

import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;
import com.google.android.gms.auth.api.signin.GoogleSignIn;
import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
import com.google.android.gms.auth.api.signin.GoogleSignInClient;
import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
import com.google.android.gms.common.SignInButton;
import com.google.android.gms.common.api.ApiException;
import com.google.firebase.auth.AuthCredential;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.auth.GoogleAuthProvider;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;

public class MainActivity extends AppCompatActivity {

    private static final int RC_SIGN_IN = 9001;
    private GoogleSignInClient googleSignInClient;
    private FirebaseAuth mAuth;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
            return insets;
        });

        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.default_web_client_id))
                .requestEmail()
                .build();

        googleSignInClient = GoogleSignIn.getClient(this, gso);
        mAuth = FirebaseAuth.getInstance();

        SignInButton signInButton = findViewById(R.id.sign_in_button);
        signInButton.setOnClickListener(v -> signIn());
    }

    private void signIn() {
        Intent signInIntent = googleSignInClient.getSignInIntent();
        startActivityForResult(signInIntent, RC_SIGN_IN);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == RC_SIGN_IN) {
            Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
            try {
                GoogleSignInAccount account = task.getResult(ApiException.class);
                if (account != null) {
                    firebaseAuthWithGoogle(account.getIdToken());
                }
            } catch (ApiException e) {
                Log.w("MainActivity", "Google sign in failed", e);
                Toast.makeText(this, "Sign in failed: " + e.getStatusCode() + " - " + e.getMessage(), Toast.LENGTH_LONG).show();
            }
        }
    }

    private void firebaseAuthWithGoogle(String idToken) {
        AuthCredential credential = GoogleAuthProvider.getCredential(idToken, null);
        mAuth.signInWithCredential(credential)
                .addOnCompleteListener(this, task -> {
                    if (task.isSuccessful()) {
                        FirebaseUser user = mAuth.getCurrentUser();
                        updateUI(user);
                    } else {
                        Log.w("MainActivity", "signInWithCredential:failure", task.getException());
                        Toast.makeText(this, "Sign in failed: " + task.getException().getMessage(), Toast.LENGTH_LONG).show();
                        updateUI(null);
                    }
                });
    }

    private void updateUI(FirebaseUser user) {
        if (user != null) {
            Toast.makeText(this, "Signed in as: " + user.getEmail(), Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(this, "Sign in failed", Toast.LENGTH_SHORT).show();
        }
    }
}

 

strings.xml 파일에 안드로이드 클라이언트 id를 선언해줘야 한다.

<resources>
	<string name="default_web_client_id">안드로이드 클라이언트 id</string>
</resources>

 

xml 코드

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <com.google.android.gms.common.SignInButton
        android:id="@+id/sign_in_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.917" />
</androidx.constraintlayout.widget.ConstraintLayout>