1、shared_preferences 插件

• 类似于 Android 中的 SharedPreferences，键值对的形式进行本地存储

1.1、引入插件

在 pubspec.yaml 中引入

dependencies:shared_preferences: ^2.1.0

在需要用到的文件中引入

import 'package:shared_preferences/shared_preferences.dart';

1.2、基本用法

• 写入数据

var sp = await SharedPreferences.getInstance();
sp.setString('name', 'Leon');

• 读取数据

var sp = await SharedPreferences.getInstance();
var name = sp.getString('name');

• 删除数据

var sp = await SharedPreferences.getInstance();
sp.remove('name');

2、代码示例

• 工具类

import 'package:shared_preferences/shared_preferences.dart';class SharedPreferencesUtils {static saveData<V>(String key, V value) async {var sp = await SharedPreferences.getInstance();var type = value.runtimeType;if (type == int) {sp.setInt(key, value as int);} else if (type == double) {sp.setDouble(key, value as double);} else if (type == String) {sp.setString(key, value as String);} else if (type == bool) {sp.setBool(key, value as bool);} else {print('类型不匹配');}}static getData(String key) async {var sp = await SharedPreferences.getInstance();print("sp.get：${sp.get(key)}");return sp.get(key);}static deleteAllData() async {var sp = await SharedPreferences.getInstance();for (String key in sp.getKeys()) {sp.remove(key);}}
}

• 页面代码

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';const String KEY_NAME = "name";
const String KEY_AGE = "age";
const String KEY_WEIGHT = "weight";
const String KEY_BOOL = "bool";class SpDemo extends StatefulWidget {const SpDemo({super.key});@overrideState<SpDemo> createState() => _SpDemoState();
}class _SpDemoState extends State<SpDemo> {var _resultShow = "";@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: const Text('SpDemo'),),body: Column(children: [ElevatedButton(onPressed: _saveData2Sp, child: const Text('保存数据')),ElevatedButton(onPressed: _getDataFromSp, child: const Text('获取数据')),ElevatedButton(onPressed: _deleteDataInSp, child: const Text('删除数据')),Text(_resultShow),],),);}void _saveData2Sp() async {await SharedPreferencesUtils.saveData(KEY_NAME, 'Leon');await SharedPreferencesUtils.saveData(KEY_AGE, 26);await SharedPreferencesUtils.saveData(KEY_WEIGHT, 60.5);await SharedPreferencesUtils.saveData(KEY_BOOL, true);setState(() {_resultShow = "保存成功";});}void _getDataFromSp() async {var name = await SharedPreferencesUtils.getData(KEY_NAME);var age = await SharedPreferencesUtils.getData(KEY_AGE);var weight = await SharedPreferencesUtils.getData(KEY_WEIGHT);var b = await SharedPreferencesUtils.getData(KEY_BOOL);print('姓名：$name\n年龄：$age\n体重：$weight\n其他：$b');setState(() {_resultShow = "姓名：$name\n年龄：$age\n体重：$weight\n其他：$b";});}void _deleteDataInSp() async {await SharedPreferencesUtils.deleteAllData();setState(() {_resultShow = "删除成功";});}
}

import 'package:flutter/material.dart';import 'SharedPreferencesDemo.dart';void main() {runApp(const MyApp());
}class MyApp extends StatelessWidget {const MyApp({super.key});@overrideWidget build(BuildContext context) {return MaterialApp(title: 'Leon Demo',theme: ThemeData(primarySwatch: Colors.blue,),home: const SpDemo(),);}
}