Login with Firebase in Android Studio

https://youtu.be/xZthfQ9Elx4

1. Firebase 연동

'Tools' - 'Firebase' - 'Authentication' - 'Authentication using a custom authentication system'

'Tools' - 'Firebase' - 'Realtime Database' - 'Get started with Realtime Database'

를 통해서 연동한다.

 

또한 Firebase 페이지에서

<Project> - 'Authentication' - 'Sign-in method'에서 이메일로 로그인하는 것을 설정해준다.

---

2. activity_register.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout ... >
 
    <EditText
        android:hint="email"
        android:id="@+id/et_email"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textEmailAddress"
        ...
        />
 
    <EditText
        android:hint="password"
        android:id="@+id/et_pwd"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPassword"
        ...
        />
 
    <Button
 
        android:id="@+id/btn_register"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="가입 완료"
        ...
        />
</androidx.constraintlayout.widget.ConstraintLayout>

회원가입을 위한 Activity를 만들어줬다.

9, 18 - inputType을 설정해줘서 간단하게 입력 형태를 정해줄 수 있다.

---

3. UserAccount.java

package com.example.firebaseemailaccount;
 
public class UserAccount {
    private String email;
    private String password;
    private String idToken;
 
    public void setIdToken(String idToken) {
        this.idToken = idToken;
    }
 
    public String getIdToken() {
        return idToken;
    }
 
    public UserAccount() { } //빈 생성자가 필요 (firebase 관련)
 
    public String getEmail() {
        return email;
    }
 
    public String getPassword() {
        return password;
    }
 
    public void setEmail(String email) {
        this.email = email;
    }
 
    public void setPassword(String password) {
        this.password = password;
    }
}
 

Database에 저장할 정보를 담을 class를 만들어준다.

 

---

4. RegisterActivity.java

package com.example.firebaseemailaccount;
 
import ...
 
public class RegisterActivity extends AppCompatActivity {
 
    private FirebaseAuth mFirebaseAuth; //파이어베이스 인증 관련
    private DatabaseReference mDatabaseReference; // 데이터베이스 관련
    private EditText et_email, et_pwd;
    private Button btn_register;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);
 
        mFirebaseAuth = FirebaseAuth.getInstance();
        mDatabaseReference = FirebaseDatabase.getInstance().getReference("FirebaseEmailAccount");
 
        et_email = findViewById(R.id.et_email);
        et_pwd = findViewById(R.id.et_pwd);
        btn_register = findViewById(R.id.btn_register);
 
        btn_register.setOnClickListener(v -> {
            String strEmail = et_email.getText().toString();
            String strPwd = et_pwd.getText().toString();
 
            mFirebaseAuth.createUserWithEmailAndPassword(strEmail, strPwd).addOnCompleteListener(RegisterActivity.this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) { //유저가 다 만들어졌을 때
                    if(task.isSuccessful()) {
                        FirebaseUser firebaseUser =mFirebaseAuth.getCurrentUser(); //로그인을 성공해서 가능한 것
                        UserAccount account = new UserAccount();
                        account.setEmail(firebaseUser.getEmail());
                        account.setPassword(strPwd);
                        account.setIdToken(firebaseUser.getUid());
 
                        //database에 저장
                        mDatabaseReference.child("userAccount").child(firebaseUser.getUid()).setValue(account);
 
                        Toast.makeText(RegisterActivity.this, "회원가입에 성공하셨습니다.", Toast.LENGTH_SHORT).show();
                    } else {
                        Toast.makeText(RegisterActivity.this, "회원가입에 실패하셨습니다.", Toast.LENGTH_SHORT).show();
                    }
                }
            });
        });
    }
}

28~46 - 회원가입을 해주고 그에 후에 대한 이벤트를 정해준다.

    39 - "FirebaseEmailAccount"/"userAccount"/<Uid>에 account를 저장한다.

---

5. activity_login.xml

로그인을 할 activity또한 만들어준다.

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout ... >
 
    <EditText
        android:hint="email"
        android:id="@+id/et_email"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textEmailAddress"
        ... />
 
    <EditText
        android:hint="password"
        android:id="@+id/et_pwd"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPassword"
        ... />
 
    <Button
 
        android:id="@+id/btn_login"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="로그인"
        ... />
 
    <Button
        android:backgroundTint="@color/black"
        android:id="@+id/btn_register_1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="회원가입"
        ... />
</androidx.constraintlayout.widget.ConstraintLayout>

---

6. LoginActivity.java

package com.example.firebaseemailaccount;
 
import ...
 
public class LoginActivity extends AppCompatActivity {
 
    private Button btn_register_1;
 
    private FirebaseAuth mFirebaseAuth; //파이어베이스 인증 관련
    private EditText et_email, et_pwd;
    private Button btn_login;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
 
        btn_register_1 = findViewById(R.id.btn_register_1);
        btn_register_1.setOnClickListener(v -> {
            Intent intent = new Intent(LoginActivity.this, RegisterActivity.class);
            startActivity(intent);
        });
 
        mFirebaseAuth = FirebaseAuth.getInstance();
 
        et_email = findViewById(R.id.et_email);
        et_pwd = findViewById(R.id.et_pwd);
 
        btn_login = findViewById(R.id.btn_login);
        btn_login.setOnClickListener(v -> {
            String strEmail = et_email.getText().toString();
            String strPwd = et_pwd.getText().toString();
 
            mFirebaseAuth.signInWithEmailAndPassword(strEmail, strPwd).addOnCompleteListener(LoginActivity.this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if(task.isSuccessful()) {
                        Intent intent = new Intent(LoginActivity.this, MainActivity.class);
                        startActivity(intent);
                        finish();
                    } else {
                        Toast.makeText(LoginActivity.this, "로그인 실패", Toast.LENGTH_SHORT).show();
                    }
                }
            });
        });
    }
}

34~45 - 로그인을 시도해주고 그 후의 이벤트를 설정할 수 있다.

---

7. activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout ...>
 
    <Button
        android:id="@+id/btn_logout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="로그아웃"
        .../>
 
</androidx.constraintlayout.widget.ConstraintLayout>

---

8. MainActivity.java

package com.example.firebaseemailaccount;
 
import ...
 
public class MainActivity extends AppCompatActivity {
    private FirebaseAuth mFirebaseAuth; //파이어베이스 인증 관련
    private DatabaseReference mDatabaseReference; // 데이터베이스 관련
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        mFirebaseAuth =FirebaseAuth.getInstance();
 
        findViewById(R.id.btn_logout).setOnClickListener(v -> {
            mFirebaseAuth.signOut();
            Intent intent = new Intent(MainActivity.this, LoginActivity.class);
            startActivity(intent);
            finish();
        });
    }
}

16 - 로그아웃을 해준다.