Flutter本地存储插件jt_preferences的使用

1. 整理后的内容中尽量提供关于“Flutter本地存储插件jt_preferences的使用”的完整示例demo

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

void main() async {
  // 初始化JtPreferences，指定加密密钥
  await JtPreferences.initialize(Directory.current.path, encryptionKey: "1X11111111111111");

  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  final String title;

  const MyHomePage({required this.title});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

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

  void _incrementCounter() async {
    setState(() {
      _counter++;
      _keyValue = await JtPreferences.getInstance().getString("key");
    });
  }

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

2. 参考我提供的内容和示例代码回答“Flutter本地存储插件jt_preferences的使用”对应的内容

示例代码如下：

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

void main() async {
  // 初始化JtPreferences，指定加密密钥
  await JtPreferences.initialize(Directory.current.path, encryptionKey: "1x11111111111111");

  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  final String title;

  const MyHomePage({required this.title});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

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

  void _incrementCounter() async {
    setState(() {
      _counter++;
      _keyValue = await JtPreferences.getInstance().getString("key");
    });
  }

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

3. 内容中的图片显示

初始化插件:
支持的数据类型:
- int
- double
- bool
- String
- Writable object
使用说明:
- 在 pubspec.yaml 文件中添加 jt_preferences 作为依赖项。

示例代码:

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

void main() async {
  // 初始化JtPreferences，指定加密密钥
  await JtPreferences.initialize(Directory.current.path, encryptionKey: "1111111111111111");

  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  final String title;

  const MyHomePage({required this.title});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

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

  void _incrementCounter() async {
    setState(() {
      _counter++;
      _keyValue = await JtPreferences.getInstance().getString("key");
    });
  }

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

更多关于Flutter本地存储插件jt_preferences的使用的实战系列教程也可以访问 https://www.itying.com/category-92-b0.html

zlyuanteng 1楼•5 天前

更多关于Flutter本地存储插件jt_preferences的使用的实战系列教程也可以访问 https://www.itying.com/category-92-b0.html

当然，以下是如何在Flutter项目中使用jt_preferences插件进行本地存储的示例代码。jt_preferences是一个轻量级的本地存储插件，类似于SharedPreferences，但提供了更简洁的API。

首先，确保你已经在pubspec.yaml文件中添加了jt_preferences依赖：

dependencies:
  flutter:
    sdk: flutter
  jt_preferences: ^x.y.z  # 请替换为最新版本号

然后运行flutter pub get来安装依赖。

接下来，你可以在你的Flutter项目中使用jt_preferences进行本地存储和读取。下面是一个完整的示例，展示了如何使用jt_preferences来存储和读取键值对。

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  String _savedValue = '';

  @override
  void initState() {
    super.initState();
    // 在初始化时读取存储的值
    _readValueFromPreferences();
  }

  Future<void> _readValueFromPreferences() async {
    String? value = await JtPreferences.getString('my_key');
    setState(() {
      _savedValue = value ?? '';
    });
  }

  Future<void> _saveValueToPreferences(String value) async {
    await JtPreferences.setString('my_key', value);
    setState(() {
      _savedValue = value;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('jt_preferences Demo'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Text(
              'Saved Value:',
              style: TextStyle(fontSize: 18),
            ),
            SizedBox(height: 8),
            TextField(
              decoration: InputDecoration(labelText: 'Enter a value'),
              onChanged: (value) {
                // 可以在用户输入时立即保存，也可以添加一个按钮来保存
                _saveValueToPreferences(value);
              },
            ),
            SizedBox(height: 24),
            Text(
              _savedValue,
              style: TextStyle(fontSize: 16, color: Colors.grey),
            ),
          ],
        ),
      ),
    );
  }
}

在这个示例中：

我们首先导入了jt_preferences包。
在_MyHomePageState类中，我们在initState方法中读取存储的值。
_readValueFromPreferences方法异步读取存储的值，并更新状态。
_saveValueToPreferences方法异步存储值。
在TextField的onChanged回调中，我们调用_saveValueToPreferences方法来实时保存用户输入的值（你也可以添加一个保存按钮来控制存储时机）。

注意：为了简化示例，我们在用户输入时立即保存值。在实际应用中，你可能希望在用户点击保存按钮或满足其他条件时才保存值。