在Bloc架构中，建议将所有不相关的逻辑单元隔离开来，包括身份验证和数据库连接。以下是一些示例代码的建议，可以实现这种分离：

身份验证：

1. 创建一个包含所有身份验证逻辑的类，例如：

class AuthService {
  final FirebaseAuth _firebaseAuth;

  AuthService({
    FirebaseAuth firebaseAuth,
  }) : _firebaseAuth = firebaseAuth ?? FirebaseAuth.instance;

  Stream get user => _firebaseAuth.authStateChanges();

  Future signInWithEmailAndPassword(String email, String password) async {
    try {
      final UserCredential userCredential = await _firebaseAuth.signInWithEmailAndPassword(
        email: email,
        password: password,
      );
      return userCredential.user;
    } on FirebaseAuthException catch (e) {
      // handle error
    }
  }

  Future signOut() async {
    await _firebaseAuth.signOut();
  }
}

2. 在视图层中使用Bloc的方式来使用这个类：

class AuthenticationBloc extends Bloc {
  final AuthService _authService;

  AuthenticationBloc(AuthService authService)
      : _authService = authService,
        super(const AuthenticationState.unknown()) {
    on(_onUserChanged);
  }

  void _onUserChanged(AuthenticationUserChanged event, Emitter emit) {
    emit(AuthenticationState.authenticated(event.user));
  }

  @override
  Future close() {
    // clean up resources
    return super.close();
  }
}

数据库连接：

1. 创建一个包含所有数据库连接逻辑的类，例如：

class FirestoreService {
  final FirebaseFirestore _firestore;

  FirestoreService({
    FirebaseFirestore firestore,
  }) : _firestore = firestore ?? FirebaseFirestore.instance;

  Stream getCollection({@required String path}) {
    return _firestore.collection(path).snapshots();
  }

  Future setData({@required String path, @required Map data}) async {
    await _firestore.doc(path).set(data);
  }

  Future delete({@required String path}) async {
    await _firestore.doc(path).delete();
  }

  Future getDocument({@required String path}) async {
    return _firestore.doc(path).get();
  }

  Future updateData(
      {@required String path, @required Map data}) async {
    await _firestore.doc(path).update(data);
  }
}

2. 在视图层中