Firebase Auth - Email login

直接輸入Email和密碼註冊登入

• 1. 進入專案管理
• 2.進入Auth管理->登入方式->啟用電子郵件/密碼
• 3.建立Ａndroid Project並且已經加入FireBase(不知道怎麼做可以參考FireBase-Android Start up)
• 4.導入FireBase的Auth library

compile 'com.google.firebase:firebase-auth:9.6.1'

• 5.然後開始寫登入流程的code

  取得FirebaseAuth這個最主要的物件,登入流程都會用到它

//取得FirebaseAuth 
private FirebaseAuth mAuth;

mAuth = FirebaseAuth.getInstance();

• 6. 建立FirebaseAuth.AuthStateListener監聽Auth狀態變化

mAuthListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user != null) {
                // User is signed in
                Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
            } else {
                // User is signed out
                Log.d(TAG, "onAuthStateChanged:signed_out");
            }
          
        }
    };
      // ...
 @Override
public void onStart() {
    super.onStart();
    //可以在onStart時,加入FirebaseAuth.AuthStateListener
    mAuth.addAuthStateListener(mAuthListener);
}

@Override
public void onStop() {
    super.onStop();
    //可以在onStop時,移除FirebaseAuth.AuthStateListener
    if (mAuthListener != null) {
        mAuth.removeAuthStateListener(mAuthListener);
    }
}

• 7.第一次登入要先註冊帳號,使用FirebaseAuth的mAuth.createUserWithEmailAndPassword,直接給email, password兩個參數,然後在addOnCompleteListener接到完成的callback,可以透過回傳得task.isSuccessful()物件判斷登入是否成功,如果失敗可以用task.getException().toString()印出錯誤訊息來看原因.

mAuth.createUserWithEmailAndPassword(email, password)
        .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
            @Override
            public void onComplete(@NonNull Task<AuthResult> task) {
                Log.d(TAG, "createUserWithEmail:onComplete:" + 
                if (!task.isSuccessful()) {
                    Toast.makeText(EmailPasswordActivity.this,      R.string.auth_failed,
                            Toast.LENGTH_SHORT).show();
                }

                // ...
            }
        });

• 8.已經註冊過了直接登入,使用FirebaseAuth的mAuth.signInWithEmailAndPassword,同上做法一樣

mAuth.signInWithEmailAndPassword(email, password)
        .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
            @Override
            public void onComplete(@NonNull Task<AuthResult> task) {
             
                if (!task.isSuccessful()) {
                    Log.w(TAG, "signInWithEmail:failed", task.getException());
                    Toast.makeText(EmailPasswordActivity.this, R.string.auth_failed,
                            Toast.LENGTH_SHORT).show();
                }

                // ...
            }
        });

• 9. 可以透過mAuth.getCurrentUser()是否為 null,來判斷是否已經登入.

if(mAuth.getCurrentUser()==null){
    loginButton.setText("Login");
}else{
    loginButton.setText("Login out");
}

• 10.登入會發現取得FirebaseUser的 displayName是null,可以用以下code去更新displayName,同時也可以設定一些使用者的個人設定,例如大頭貼...

 UserProfileChangeRequest profileUpdates = new UserProfileChangeRequest.Builder()
                .setDisplayName(nickName)
                .build();
        user.updateProfile(profileUpdates)
                .addOnCompleteListener(new OnCompleteListener<Void>() {
                    @Override
                    public void onComplete(@NonNull Task<Void> task) {
                        if (task.isSuccessful()) {
                            Log.d(TAG, "User profile updated.");
                            finish();
                        }
                    }
                });

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