[英]Flutter - How to write a file from assets?
What I need is to "edit" a text file that is on my assets folder.我需要的是“编辑”我资产文件夹中的文本文件。 To read a file from assets I can use this:
要从资产中读取文件,我可以使用它:
`Future<String> setFileData(String path) async {
return await rootBundle.loadString(path);
}`
But how can I write that file from the same path?但是如何从同一路径写入该文件?
This document can help you: Read and write files - Flutter本文档可以帮助您: 读写文件 - Flutter
Complete example完整示例
import 'dart:async';
import 'dart:io';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
void main() {
runApp(
MaterialApp(
title: 'Reading and Writing Files',
home: FlutterDemo(storage: CounterStorage()),
),
);
}
class CounterStorage {
Future<String> get _localPath async {
final directory = await getApplicationDocumentsDirectory();
return directory.path;
}
Future<File> get _localFile async {
final path = await _localPath;
return File('$path/counter.txt');
}
Future<int> readCounter() async {
try {
final file = await _localFile;
// Read the file
String contents = await file.readAsString();
return int.parse(contents);
} catch (e) {
// If encountering an error, return 0
return 0;
}
}
Future<File> writeCounter(int counter) async {
final file = await _localFile;
// Write the file
return file.writeAsString('$counter');
}
}
class FlutterDemo extends StatefulWidget {
final CounterStorage storage;
FlutterDemo({Key key, @required this.storage}) : super(key: key);
@override
_FlutterDemoState createState() => _FlutterDemoState();
}
class _FlutterDemoState extends State<FlutterDemo> {
int _counter;
@override
void initState() {
super.initState();
widget.storage.readCounter().then((int value) {
setState(() {
_counter = value;
});
});
}
Future<File> _incrementCounter() {
setState(() {
_counter++;
});
// Write the variable as a string to the file.
return widget.storage.writeCounter(_counter);
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('Reading and Writing Files')),
body: Center(
child: Text(
'Button tapped $_counter time${_counter == 1 ? '' : 's'}.',
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
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