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: 
     
      [                  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: 
      
       [                  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
       
         get _localPath async {    final directory = await getApplicationDocumentsDirectory();    return directory.path;  }  Future
        
          get _localFile async {    final path = await _localPath;    return File('$path/text.txt');  }  Future
         
           readFile() async {    try {      final file = await _localFile;      String content = await file.readAsString();      bloc.dataBloc.add(content);      return content;    } catch (e) {      return '';    }  }  Future
          
            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
           
             cleanFile() async { final file = await _localFile; bloc.dataBloc.add('clean'); return file.writeAsString(''); }}