main.dart
import 'package:flutter/material.dart';
import 'dart:io';
import 'dart:convert';
import 'package:path_provider/path_provider.dart';
​
void main() {
runApp(new MaterialApp(
home: new Home(),
));
}
​
class Home extends StatefulWidget {
@override
State createState() => new HomeState();
}
​
class HomeState extends State<Home> {
​
TextEditingController keyInputController = new TextEditingController();
TextEditingController valueInputController = new TextEditingController();
​
File jsonFile;
Directory dir;
String fileName = "myJSONFile.json";
bool fileExists = false;
Map<String, String> fileContent;
​
@override
void initState() {
super.initState();
getApplicationDocumentsDirectory().then((Directory directory) {
dir = directory;
jsonFile = new File(dir.path + "/" + fileName);
fileExists = jsonFile.existsSync();
if (fileExists) this.setState(() => fileContent = JSON.decode(jsonFile.readAsStringSync()));
});
}
​
@override
void dispose() {
keyInputController.dispose();
valueInputController.dispose();
super.dispose();
}
​
void createFile(Map<String, String> content, Directory dir, String fileName) {
print("Creating file!");
File file = new File(dir.path + "/" + fileName);
file.createSync();
fileExists = true;
file.writeAsStringSync(JSON.encode(content));
}
​
void writeToFile(String key, String value) {
print("Writing to file!");
Map<String, String> content = {key: value};
if (fileExists) {
print("File exists");
Map<String, String> jsonFileContent = json.decode(jsonFile.readAsStringSync());
jsonFileContent.addAll(content);
jsonFile.writeAsStringSync(JSON.encode(jsonFileContent));
} else {
print("File does not exist!");
createFile(content, dir, fileName);
}
this.setState(() => fileContent = JSON.decode(jsonFile.readAsStringSync()));
print(fileContent);
}
​
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(title: new Text("JSON Tutorial"),),
body: new Column(
children: <Widget>[
new Padding(padding: new EdgeInsets.only(top: 10.0)),
new Text("File content: ", style: new TextStyle(fontWeight: FontWeight.bold),),
new Text(fileContent.toString()),
new Padding(padding: new EdgeInsets.only(top: 10.0)),
new Text("Add to JSON file: "),
new TextField(
controller: keyInputController,
),
new TextField(
controller: valueInputController,
),
new Padding(padding: new EdgeInsets.only(top: 20.0)),
new RaisedButton(
child: new Text("Add key, value pair"),
onPressed: () => writeToFile(keyInputController.text, valueInputController.text),
)
],
),
);
}
}