bloc控制读写文件

import 'package:flutter/material.dart';
import 'dart:io';
import 'package:path_provider/path_provider.dart';
import 'package:rxdart/rxdart.dart';

main() => runApp(
    MyApp(
      storage: TextStorage(
          bloc: DataBloc()
      )
    )
);

class MyApp extends StatelessWidget {
  MyApp({this.storage});

  final TextStorage storage;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('ass'),),
        body: StreamBuilder(
          stream: storage.bloc.dataBloc.stream,
          builder: (context, snapshot) {
            if (snapshot.hasData) {
              return Container(child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  Text(snapshot.data),

                  RaisedButton(child: Text('add'), onPressed: () {
                    storage.writeFile('add hello');
                  },),
                  RaisedButton(child: Text('check'), onPressed: () {
                    storage.readFile();
                  },),
                  RaisedButton(child: Text('clean'), onPressed: () {
                    storage.cleanFile();
                  },),
                ],
              ),);
            } else {
              return Container(child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  RaisedButton(
                      child: Text('start'),
                      onPressed: (){
                        storage.writeFile('add hello');
                      }),

                ],
              ),
              );
            }
          },
        ),

      ),
    );
  }
}

class DataBloc {
  PublishSubject dataBloc = PublishSubject();

  DataBloc() {
    dataBloc.listen(onData);
  }

  void onData(value) {}
}

class TextStorage {
  TextStorage({this.bloc});

  DataBloc bloc;

  Future<String> get _localPath async {
    final directory = await getApplicationDocumentsDirectory();
    return directory.path;
  }

  Future<File> get _localFile async {
    final path = await _localPath;
    return File('$path/text.txt');
  }

  Future<String> readFile() async {
    try {
      final file = await _localFile;
      String content = await file.readAsString();
      bloc.dataBloc.add(content);
      return content;
    } catch (e) {
      return '';
    }
  }

  Future<File> writeFile(String text) async {
    final file = await _localFile;
    bloc.dataBloc.add('this is test');
    print('get $text, but write: this is test');
    return file.writeAsString('$text\r\n', mode: FileMode.append);
  }

  Future<File> cleanFile() async {
    final file = await _localFile;
    bloc.dataBloc.add('clean');
    return file.writeAsString('');
  }
}