Flutter进阶第10篇： 本地存储，封装本地存储类，实现最简单的状态管理

引入第三方库：shared_preferences

设置值：

SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.setString(key, value);
prefs.setBool(key, value)
prefs.setDouble(key, value)
prefs.setInt(key, value)
prefs.setStringList(key, value)

获取值：

SharedPreferences prefs = await SharedPreferences.getInstance();
var data=prefs.getString("name");

删除值：

SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.remove(key); //删除指定键
prefs.clear();//清空键值对

完整代码：

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

class StoragePage extends StatefulWidget {
  StoragePage({Key key}) : super(key: key);

  _StoragePageState createState() => _StoragePageState();
}

class _StoragePageState extends State<StoragePage> {

  _saveData() async{
      SharedPreferences sp=await SharedPreferences.getInstance();

      sp.setString("username", "张三111");

       sp.setString("age", "26");
       
  }
  _getData() async{
      SharedPreferences sp=await SharedPreferences.getInstance();

      print(sp.getString("username"));

      print(sp.getString("age"));
  }
  _removeData() async{
     SharedPreferences sp=await SharedPreferences.getInstance();

      print(sp.remove("age"));

  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("本地存储"),
      ),
      body: Center(
        child: Column(mainAxisAlignment: MainAxisAlignment.center, children: [
          RaisedButton(
            child: Text('保存数据'),
            onPressed: _saveData,
          ),
          SizedBox(height: 10),
          RaisedButton(
            child: Text('获取数据'),
            onPressed:_getData,
          ),
           SizedBox(height: 10),
          RaisedButton(
            child: Text('清除数据'),
            onPressed:_removeData,
          )         
        ]),
      ),
    );
  }
}

简单封装：

import 'package:shared_preferences/shared_preferences.dart';

class Storage{

  static Future<void> setString(key,value) async{
       SharedPreferences sp=await SharedPreferences.getInstance();
       sp.setString(key, value);
  }

  static Future<String> getString(key) async{
       SharedPreferences sp=await SharedPreferences.getInstance();
       return sp.getString(key);
  }

  static Future<void> remove(key) async{
       SharedPreferences sp=await SharedPreferences.getInstance();
       sp.remove(key);
  }
}