[플러터] 28일차 - SharedPreference

플러터에서 앱의 데이터를 저장하는 방법 중, SharedPreference를 사용해서 간단한 데이터를 저장한다.

 

환경 준비

dependencies:
  flutter:
    sdk: flutter

  shared_preferences: ^2.0.6

 

 

코드

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, required this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;


  void _setData(int value) async {
    SharedPreferences pref = await SharedPreferences.getInstance();
    pref.setInt('count', value);
  }

  void _loadData() async {
    SharedPreferences pref = await SharedPreferences.getInstance();
    setState(() {
      var value = pref.getInt('count');
      _counter = value ?? 0;
    });
  }
  
  @override
  void initState() {
    super.initState();
    _loadData();
  }

  void _incrementCounter() {
    setState(() {
      _counter++;
      _setData(_counter);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}

 

이제 앱을 실행 후 버튼을 눌러 숫자를 증가시키고, 앱을 종료했다가 다시 실행하면 증가한 숫자가 그대로 보인다.

 

 

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