Flutter学习第四课（SharedPreferences本地存储的简单使用） flutter

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一：第一步：Main.dart界面

import 'package:flutter/material.dart'; import 'package:flutter_first/storage/storage_sp.dart'; void main() { runApp(MyApp()); }class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: "SharedPreferences示例", theme: ThemeData(primarySwatch: Colors.blue), home: StorageSp(), ); } }

【Flutter学习第四课（SharedPreferences本地存储的简单使用）】第二步：SharePrefences 数据存储界面

import 'package:flutter/material.dart'; import 'package:shared_preferences/shared_preferences.dart'; class StorageSp extends StatefulWidget { const StorageSp({Key? key}) : super(key: key); @override State createState() => _StorageSpState(); }class _StorageSpState extends State { //第一步：实例化本地存储对象 Future _prefs = SharedPreferences.getInstance(); //昵称及选择语言的值文本输入的控制器 var controller = TextEditingController(); //定义变量 value_dart,value_js,value_java bool value_dart = false; bool value_js = false; bool value_java = false; @override void initState() { super.initState(); initFromCache(); }@override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text("SharedPreferences示例"), ), body: Container( padding: EdgeInsets.all(15), child: Column( crossAxisAlignment: CrossAxisAlignment.center, children: [ TextField( controller: controller, //一个自定义控制器，可实现类似TextEditingController decoration: InputDecoration( //一个输入框 labelText: "昵称:", hintText: "请输入名称"), ), Text("你喜欢的编程语言"), Row( mainAxisAlignment: MainAxisAlignment.spaceBetween, children: [ Text("Dart"), //Switch 表示开关组件value选中的值，onChanged 改变时触发的事件 Switch( value: value_dart, onChanged: (isChanged) { //设置状态改变要存储的值 setState(() { this.value_dart = isChanged; }); }) ], ), Row( mainAxisAlignment: MainAxisAlignment.spaceBetween, children: [ Text("JavaScript"), Switch( value: value_js, onChanged: (isChanged){ //设置状态改变要存储的值 setState(() { this.value_js=isChanged; }); })], ), Row( mainAxisAlignment: MainAxisAlignment.spaceBetween, children: [ Text("Java"), Switch( value: value_java, onChanged: (isChanged){ //设置状态改变要存储的值 setState(() { this.value_java=isChanged; }); })], ),MaterialButton( child: Text("保存"), onPressed: (){ saveInfo(controller.text); })], ), ), ); }//从缓存中获取信息填充 void initFromCache() async { //获取SharedPreferences对象 final SharedPreferences prefs = await _prefs; //根据键（key）获取本地存储的值（value） final value_nickname = prefs.getString("key_nickname"); final value_dart = prefs.getBool("key_dart"); final value_js = prefs.getBool("key_js"); final value_java = prefs.getBool("key_java"); //获取到缓存中的值后，使用setState更新界面信息 setState(() { controller.text = (value_nickname == null ? "" : value_nickname); this.value_dart = (value_dart == null ? false : value_dart); this.value_js = (value_js == null ? false : value_js); this.value_java = (value_java == null ? false : value_java); }); } //保存界面的输入选择信息 void saveInfo(String value_nickname)async{ final SharedPreferences prefs=await _prefs; prefs.setString("key_nickname", value_nickname); prefs.setBool("key_dart", value_dart); prefs.setBool("key_js", value_js); prefs.setBool("key_java", value_java); }}

在Android下的数据data/data/包名/shared_prefs