[Day25] Flutter - Application Authentication (part9)

前言

Hi, 我是鱼板伯爵接着就是来验证登入状态，如果已经登入就跳转到首页否则就在登入画面，看完我这句话就知道要使用Bloc了，只要是画面与功能就要使用到Bloc。以上是一个基本的状态你还可以检查有没有重复登入等...。

完整程序码

需要具备知识

• 基本元件应用
• 专案架构 (Domain Driven Design)
• 管理程序码好帮手 ( Bloc )
• 大海捞针不是办法 ( Dartz )

Authentication：Event

事件分成三个，AppStarted用於开启APP时触发的事件，用来检查有没有登入，如果没有就跳转到登入介面，LoggedIn用於登入成功时触发把未登入状态切换成已登入状态，最後就LoggedOut是登出按钮触发时使用，将已登入状态切换成未登入状态。

part of 'authentication_bloc.dart';

abstract class AuthenticationEvent extends Equatable {
  const AuthenticationEvent();

  @override
  List<Object> get props => [];
}

class AppStarted extends AuthenticationEvent {}

class LoggedIn extends AuthenticationEvent {}

class LoggedOut extends AuthenticationEvent {}

Authentication：State

状态可以分成两个，未认证与认证，如果认证成功就切换到首页否则就停留在登入画面。

part of 'authentication_bloc.dart';

abstract class AuthenticationState extends Equatable {
  const AuthenticationState();

  @override
  List<Object> get props => [];
}

class AuthenticationInitial extends AuthenticationState {}


class Authenticated extends AuthenticationState {
  final String displayName;

  const Authenticated(this.displayName);

  @override
  List<Object> get props => [displayName];
}

class Unauthenticated extends AuthenticationState {}

Authentication：Bloc

判断三个事件所要触法的功能，写到这边时大家应该都对这个架构感觉了吧，是不是觉得越来越美了呢。

import 'dart:async';
import 'dart:developer';

import 'package:bloc/bloc.dart';
import 'package:equatable/equatable.dart';
import 'package:stunning_tribble/infrastructure/auth/auth_repository.dart';

part 'authentication_event.dart';
part 'authentication_state.dart';

class AuthenticationBloc
    extends Bloc<AuthenticationEvent, AuthenticationState> {
  final AuthRepository _userRepository;

  AuthenticationBloc({
    required AuthRepository userRepository,
  })  : _userRepository = userRepository,
        super(AuthenticationInitial());

  @override
  Stream<AuthenticationState> mapEventToState(
    AuthenticationEvent event,
  ) async* {
    if (event is AppStarted) {
      yield* _mapAppStartedToState();
    } else if (event is LoggedIn) {
      yield* _mapLoggedInToState();
    } else if (event is LoggedOut) {
      yield* _mapLoggedOutToState();
    }
  }

  Stream<AuthenticationState> _mapAppStartedToState() async* {
    final isSignedIn = await _userRepository.isSignedIn();
    yield* isSignedIn.fold(
      (failure) async* {
        log("$failure");
        yield Unauthenticated();
      },
      (isSignedInSuccess) async* {
        yield* _mapLoggedInToState();
      },
    );
  }

  Stream<AuthenticationState> _mapLoggedInToState() async* {
    final user = await _userRepository.getUser();
    yield* user.fold(
      (failure) async* {
        log("$failure");
        yield Unauthenticated();
      },
      (user) async* {
        yield Authenticated(user.displayName.toString());
      },
    );
  }

  Stream<AuthenticationState> _mapLoggedOutToState() async* {
    final signOut = await _userRepository.signOut();
    yield* signOut.fold(
      (failure) async* {
        log("$failure");
        yield Unauthenticated();
      },
      (r) async* {
        yield Unauthenticated();
      },
    );
  }
}