Flutter Slider – 保持 on/off 即使用户关闭应用程序并使用 Getx 重新访问

Question

Flutter 初学者需要帮助。即使我们关闭应用程序并使用 Getx 或其他一些 Statemanegment 重新访问应用程序，如何保持滑块在原位并保持值。按照本教程 Flutter Switch，我尝试使用 Slider 制作相同的东西，但我的编码知识不够，我找不到任何教程来使用 Slider 制作相同的东西。


import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
 const MyApp({Key? key}) : super(key: key);

 static const String _title = 'Flutter Code Sample';

 @override
 Widget build(BuildContext context) {
   return MaterialApp(
     title: _title,
     home: Scaffold(
       appBar: AppBar(title: const Text(_title)),
       body: const MyStatefulWidget(),
     ),
   );
 }
}

class MyStatefulWidget extends StatefulWidget {
 const MyStatefulWidget({Key? key}) : super(key: key);

 @override
 State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
 double _currentSliderValue = 20;

 @override
 Widget build(BuildContext context) {
   return Slider(
     value: _currentSliderValue,
     min: 0,
     max: 100,
     divisions: 5,
     label: _currentSliderValue.round().toString(),
     onChanged: (double value) {
       setState(() {
         _currentSliderValue = value;
       });
     },
   );
 }
}

Answer 1

您链接的教程对于初学者来说似乎过于复杂，因为它同时解释了存储和状态管理。

对我来说似乎更容易，只专注于存储部分。

您可以使用 shared_prefences，如 official flutter pages. But this is only for simple data (get_storage too). If your app will be more complicated and you have to store more data, you should think about some other storage like sqlite 中所述。

因为我不知道 getX，这里有一个 sharedPreferences 的例子：

1.Add 打包到 pubspec.yaml:

dependencies:
  shared_preferences: "<newest version>"

2.Your 代码 shared_preferences:

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

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const MyStatefulWidget(),
      ),
    );
  }
}

class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key}) : super(key: key);

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  double _currentSliderValue = 20;

  @override
  void initState() {
    super.initState();
    _loadSlider();
  }

  //Loading slider value on start
  void _loadSlider() async {
    final prefs = await SharedPreferences.getInstance();
    setState(() {
      _currentSliderValue = (prefs.getDouble('slider') ?? 20);
    });
  }

  // change slider value to value
  void _changeSlider(double value) {
    setState(() {
      _currentSliderValue = value;
    });
  }

  // store slider value
  void _storeSlider() async {
    final prefs = await SharedPreferences.getInstance();
    prefs.setDouble('slider', _currentSliderValue);
  }

  @override
  Widget build(BuildContext context) {
    return Slider(
      value: _currentSliderValue,
      min: 0,
      max: 100,
      divisions: 5,
      label: _currentSliderValue.round().toString(),
      onChanged: (double value) {
        _changeSlider(value);
        _storeSlider();
      },
    );
  }
}

Flutter Slider – 保持 on/off 即使用户关闭应用程序并使用 Getx 重新访问

Flutter Slider – Keep it on/off even when user close app & re-visit with Getx

flutter

dart

flutter-getx