demo/xinhuaribao/lib/provider/news_provider.dart

import 'package:connectivity_plus/connectivity_plus.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:news_app/http/http_util.dart';
import 'package:news_app/http/model_parser.dart';
import 'package:news_app/ui/news/main_news_page.dart';
import 'package:news_app/util/log.util.dart';

import '../constant/api_const.dart';
import '../model/activity_banner_model.dart';
import '../model/news_data_model.dart';
import 'network_provider.dart';

class NewsNotifier extends FamilyNotifier<NewsState, int> {
  int tabIndex = 0;
  bool _hasConnectedOnce = false;

  @override
  NewsState build(int index) {
    tabIndex = index;
    // 监听网络变化，在首次联网时触发加载
    ref.listen<AsyncValue<List<ConnectivityResult>>>(connectivityProvider, (
      previous,
      next,
    ) {
      final results = next.asData?.value ?? [];

      final hasNetwork =
          results.isNotEmpty && !results.contains(ConnectivityResult.none);

      if (hasNetwork && !_hasConnectedOnce) {
        _hasConnectedOnce = true;
        fetchBannerList();
        fetchNewsItemList(1);
      }
    });
    return NewsState(bannerList: [], newsDataModel: NewsDataModel());
  }

  Future<void> fetchBannerList() async {
    final model = ref.read(newsCategoryProvider)[tabIndex];
    consoleLog(model.name);
    final jsonData = await HttpUtil().get(
      apiBannerList,
      queryParameters: {"type": "", "categoryId": model.catalogId},
    );
    final bannerData = ModelParser.parseList(
      jsonData,
      ActivityBannerModel.fromJson,
    );
    state = state.copyWith(bannerList: bannerData);
  }

  Future<void> fetchNewsItemList(int pageNum) async {
    final model = ref.read(newsCategoryProvider)[tabIndex];
    consoleLog(model.name);
    final jsonData = await HttpUtil().get(
      apiNewsList,
      queryParameters: {
        "cid": model.catalogId,
        "sid": model.siteId,
        "pp": "",
        "text": "true",
        "pageNum": pageNum.toString(),
        "pageSize": 10,
      },
    );
    final response = ModelParser.parseObject(jsonData, NewsDataModel.fromJson);
    final oldRecords = state.newsDataModel.records ?? [];
    state = state.copyWith(
      newsDataModel: response.copyWith(
        total: response.total,
        size: response.size,
        current: response.current,
        pages: response.pages,
        records:
            pageNum == 1
                ? response.records
                : [...oldRecords, ...?response.records],
      ),
    );
  }
}

class NewsState {
  final List<ActivityBannerModel> bannerList;
  final NewsDataModel newsDataModel;

  NewsState({required this.bannerList, required this.newsDataModel});

  NewsState copyWith({
    List<ActivityBannerModel>? bannerList,
    NewsDataModel? newsDataModel,
  }) {
    return NewsState(
      bannerList: bannerList ?? this.bannerList,
      newsDataModel: newsDataModel ?? this.newsDataModel,
    );
  }
}