Google SignIn

GoogleTestActivity.kt

class GoogleTestActivity : AppCompatActivity() {

    /**
     * [Document]: https://firebase.google.com/docs/auth/android/google-signin?authuser=0#top_of_page
     * [Blog]: https://sh-itstory.tistory.com/60
     */


    val TAG = "FFF"


    private lateinit var googleSignInClient: GoogleSignInClient     //구글 API 클라이언트
    private lateinit var auth: FirebaseAuth                         //파이어베이스 인증객체
    private val RC_SIGN_IN = 100                                    //구글로그인 rusult 상수




    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_google_test)

        // Configure Google Sign In
        val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestIdToken(getString(R.string.default_web_client_id))
            .requestEmail()
            .build()

        googleSignInClient = GoogleSignIn.getClient(this, gso)

        // Initialize Firebase Auth
        auth = FirebaseAuth.getInstance()
        initLayout()
    }


    private fun initLayout(){

        //버튼 모양만 잡아줄 뿐 기능은 없음
        btn_googleSignIn.setOnClickListener {
            signIn()
        }

        btn_logout.setOnClickListener {
            signOut()
        }

        btn_google.setOnClickListener {
            signIn()
        }
    }


    public override fun onStart() {
        super.onStart()

        // Check if user is signed in (non-null) and update UI accordingly.
        val currentUser = auth.currentUser
        Log.d(TAG, "onStart()에서 로그인확인: $currentUser, ${currentUser?.displayName} ${currentUser?.email}")
    }



    private fun firebaseAuthWithGoogle(acct: GoogleSignInAccount) {
        Log.d(TAG, "firebaseAuthWithGoogle:" + acct.id!!)

        val credential = GoogleAuthProvider.getCredential(acct.idToken, null)

        auth.signInWithCredential(credential).addOnCompleteListener(this) { task ->

                if (task.isSuccessful) {
                    // Sign in success, update UI with the signed-in user's information
                    Log.d(TAG, "signInWithCredential:success")
                    val user = auth.currentUser
                    updateUI(user)

                } else {
                    // If sign in fails, display a message to the user.
                    Log.w(TAG, "signInWithCredential:failure", task.exception)
                    Toast.makeText(this, "Authentication Failed.", Toast.LENGTH_LONG).show()
                    updateUI(null)
                }

        }
    }


    private fun updateUI(user: FirebaseUser?){
        Log.d(TAG, "updateUI( $user )")
    }


    private fun signOut(){
        Log.d(TAG, "signOut()")
        FirebaseAuth.getInstance().signOut()
    }


    private fun signIn() {
        val signInIntent = googleSignInClient.signInIntent
        startActivityForResult(signInIntent, RC_SIGN_IN)
    }


    public override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)

        // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
        if (requestCode == RC_SIGN_IN) {
            val task = GoogleSignIn.getSignedInAccountFromIntent(data)
            try {
                // Google Sign In was successful, authenticate with Firebase
                val account = task.getResult(ApiException::class.java)
                firebaseAuthWithGoogle(account!!)
            } catch (e: ApiException) {
                // Google Sign In failed, update UI appropriately
                Log.w(TAG, "Google sign in failed", e)
                // ...
            }
        }
    }

}

activity_google_test.kt

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".GoogleTestActivity">

    <com.google.android.gms.common.SignInButton
            android:id="@+id/btn_googleSignIn"
            android:layout_width="250dp"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            app:layout_constraintEnd_toEndOf="parent" app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintStart_toStartOf="parent" app:layout_constraintBottom_toBottomOf="parent"
    >
    </com.google.android.gms.common.SignInButton>
    <Button
            android:text="로그아웃"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btn_logout" android:layout_marginTop="32dp"
            app:layout_constraintTop_toBottomOf="@+id/btn_googleSignIn" app:layout_constraintStart_toStartOf="parent"
            android:layout_marginStart="8dp" app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp"/>
    <Button
            android:text="구글로그인"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btn_google" android:layout_marginBottom="32dp"
            app:layout_constraintBottom_toTopOf="@+id/btn_googleSignIn"
            app:layout_constraintStart_toStartOf="@+id/btn_googleSignIn"
            app:layout_constraintEnd_toEndOf="@+id/btn_googleSignIn"/>

</android.support.constraint.ConstraintLayout>

AndroidManifest.xml

<uses-permission android:name="android.permission.INTERNET"/>

Build.gradle

implementation 'com.google.firebase:firebase-auth:16.2.1'
implementation 'com.google.android.gms:play-services-auth:16.0.1'

이건 먼저 콘솔에 가서 세팅을 다 해놓고,

Tools > Firebase 을 이용하면 자동으로 해준다.

app폴더 안에 파일 넣는 것도 해줌.