Flutter网络请求插件flutter_cpnetworking_service的使用

Flutter网络请求插件flutter_cpnetworking_service的使用

flutter_cpnetworking_service 是一个网络请求封装库，它使用 dio 来处理 HTTP 请求，并利用 flutter_secure_storage（在 iOS 和 Android 平台上）或 shared_preferences（在 Web 平台上）来存储令牌或其他敏感数据。该库还允许将令牌用作 HTTP 请求中的授权信息。

使用

我们将使用一个随机新闻 API，该 API 生成新闻数据并以 JSON 格式返回。

基本新闻模型

class NewsEnity implements BaseModelInterface {
  final String title;
  final String id;
  final String description;
  final List<String> categories;
  final List<String> medias;
  final int published;

  String formattedPublished(String languageCode) {
    var date = DateTime.fromMillisecondsSinceEpoch(published);
    var formattedDate = DateFormat.yMMMMd(languageCode).format(date);
    return formattedDate;
  }

  NewsEnity({
    @required this.title,
    @required this.id,
    @required this.description,
    @required this.medias,
    @required this.categories,
    @required this.published
  });

  factory NewsEnity.fromJson(Map<String, dynamic> json) {
    List<String> category;
    if (json['category'] is String) {
      category = [json['category'].toString()];
    }
    return NewsEnity(
      title: json['title'],
      id: json['id'],
      description: json['description'],
      categories: category ??
          (json['category'] as List).map((e) => e.toString()).toList() ??
          [],
      medias: (json['medias'] as List).map((e) => e.toString()).toList() ?? [],
      published: json['published']
    );
  }

  [@override](/user/override)
  Map<String, dynamic> toJson() {
    throw UnimplementedError();
  }
}

仓库

仓库抽象类将介于我们的架构中的高层组件之间（如 Bloc 和客户端 API 提供程序）。

abstract class NewsRepository {
  Future<ResponseListData<NewsEnity>> fetchHotNews();
  Future<ResponseListData<NewsEnity>> fetchLocalNews();
}

enum _Path { Hot, Local }

class _URLPathHelper {
  static String value(_Path value) {
    switch (value) {
      case _Path.Hot:
        return '/application/news/hot';
      case _Path.Local:
        return '/application/news/local';
      default:
        return '';
    }
  }
}

class NewsClient extends APIProvider implements NewsRepository {
  [@override](/user/override)
  Future<ResponseListData<NewsEnity>> fetchHotNews() async {
    var input = DefaultInputService(path: _URLPathHelper.value(_Path.Local));
    final response = await super.request(input: input);
    var result = (response.data['data'] as List)
        .map((e) => NewsEnity.fromJson(e))
        .toList();
    return ResponseListData<NewsEnity>(() => result);
  }

  [@override](/user/override)
  Future<ResponseListData<NewsEnity>> fetchLocalNews() {
    return Future.error(AppError(message: ''));
  }

  NewsClient({
    @required StorageTokenProcessor storageTokenProcessor,
    @required NetworkConfigurable networkConfigurable,
    Interceptor interceptor
  }) : super(
    storageTokenProcessor: storageTokenProcessor,
    networkConfiguration: networkConfigurable,
    interceptor: interceptor
  );
}

Bloc

让我们添加架构中的高层组件之一，即 Bloc（业务逻辑组件）。NewsBloc 是唯一可以从 UI 类中使用的组件（在清洁架构的术语中）。NewsBloc 从仓库获取数据并通过状态通知。

class NewsBloc extends Bloc<NewsEvent, NewsState> {
  final NewsRepository newsRepository;
  final StorageTokenProcessor storageTokenProcessor;

  NewsBloc({
    @required this.newsRepository,
    @required this.storageTokenProcessor
  }) : super(NewsInitial());

  [@override](/user/override)
  Stream<NewsState> mapEventToState(NewsEvent event) async* {
    if (event is FetchNews) {
      yield NewsLoading();
      yield* _fetchNews(event);
    }
  }

  Stream<NewsState> _fetchNews(FetchNews params) async* {
    try {
      var localNews = await newsRepository.fetchHotNews();
      yield NewsLoaded(hotNews: [], localNews: localNews.data);
    } on AppError catch (e, stack) {
      yield NewsError(message: e.message);
    }
  }
}

[@immutable](/user/immutable)
abstract class NewsEvent {}

class FetchNews extends NewsEvent {}

[@immutable](/user/immutable)
abstract class NewsState {}

class NewsLoaded extends NewsState {
  final List<NewsEnity> hotNews;
  final List<NewsEnity> localNews;

  NewsLoaded({
    @required this.hotNews,
    @required this.localNews,
  });
}