如何在flutter bloc中实现分页

dependencies:
  flutter_bloc: ^7.0.0

import 'package:flutter_bloc/flutter_bloc.dart';

class PaginationBloc extends Bloc<PaginationEvent, PaginationState> {
  PaginationBloc() : super(PaginationInitial());

  @override
  Stream<PaginationState> mapEventToState(PaginationEvent event) async* {
    if (event is PaginationFetch) {
      // 处理分页逻辑
      try {
        // 发起网络请求获取数据
        // 解析数据并更新状态
        yield PaginationSuccess(data: fetchedData);
      } catch (error) {
        yield PaginationFailure(error: error.toString());
      }
    }
  }
}

// 定义事件
abstract class PaginationEvent {}

class PaginationFetch extends PaginationEvent {}

// 定义状态
abstract class PaginationState {}

class PaginationInitial extends PaginationState {}

class PaginationSuccess extends PaginationState {
  final List<Data> data;

  PaginationSuccess({required this.data});
}

class PaginationFailure extends PaginationState {
  final String error;

  PaginationFailure({required this.error});
}

import 'package:flutter_bloc/flutter_bloc.dart';

class PaginationPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      create: (context) => PaginationBloc(),
      child: Scaffold(
        appBar: AppBar(
          title: Text('Pagination Example'),
        ),
        body: BlocBuilder<PaginationBloc, PaginationState>(
          builder: (context, state) {
            if (state is PaginationInitial) {
              // 初始状态，显示加载中的UI
              return Center(
                child: CircularProgressIndicator(),
              );
            } else if (state is PaginationSuccess) {
              // 成功获取数据，显示数据列表
              return ListView.builder(
                itemCount: state.data.length,
                itemBuilder: (context, index) {
                  return ListTile(
                    title: Text(state.data[index].title),
                    subtitle: Text(state.data[index].description),
                  );
                },
              );
            } else if (state is PaginationFailure) {
              // 获取数据失败，显示错误信息
              return Center(
                child: Text('Error: ${state.error}'),
              );
            }
            return Container();
          },
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () {
            // 触发分页事件
            context.read<PaginationBloc>().add(PaginationFetch());
          },
          child: Icon(Icons.refresh),
        ),
      ),
    );
  }
}

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Pagination Example',
      home: PaginationPage(),
    );
  }
}