Flutter本地存储SharedPreferences

和NSUserDefault一样，以键值对的形式保存数据到本地
导入框架：

shared_preferences:

引入头文件:

import 'package:shared_preferences/shared_preferences.dart';

创建一个工具类用来管理用户本地数据
UserManager.dart:

import 'package:flutter_webapp/UserModel.dart';
import 'package:shared_preferences/shared_preferences.dart';

class UserManager {
  // save
  static Future save(String key, String value) async {
    SharedPreferences pref = await SharedPreferences.getInstance();
    pref.setString(key, value);
  }

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

  // delete
  static Future delete(String key) async {
    SharedPreferences pref = await SharedPreferences.getInstance();
    pref.remove(key);
  }

  // clear
  static Future clear() async {
    SharedPreferences pref = await SharedPreferences.getInstance();
    pref.clear();
  }  
}

调用:

UserManager.save('userId', myuserId);