flutter-template/lib/common/states.dart

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

/// 状态储存工具类
class States {
  // 用于首页初始化时从本地持久化存储或应用配置中读取全局状态
  static init(BuildContext context) {
    _readStates(context);
  }

  // 读取状态，异步操作
  static _readStates(BuildContext context) async {
    // 从本地储存读缓存状态
    SharedPreferences prefs = await SharedPreferences.getInstance();
    var sc = prefs.getBool(StateKey.ShowContact);

    Provider.of<UserStatus>(context, listen: false).userName = prefs.getString(StateKey.UserName) ?? '';
    Provider.of<UserStatus>(context, listen: false).userToken = prefs.getString(StateKey.UserToken) ?? '';

    Provider.of<AppVersion>(context, listen: false).showContact = (null == sc ? true : sc);

    // 当前APP版本不从缓存读，直接从应用包信息获取（实际是在pubspec.yaml文件中配置的version配置项）
    PackageInfo packageInfo = await PackageInfo.fromPlatform();
    Provider.of<AppVersion>(context, listen: false).appVersion = packageInfo.version.split('+')[0]; // 不管+号后的构建号
  }

  // 重置缓存状态
  static reset(BuildContext context) async {
    Provider.of<UserStatus>(context, listen: false).userName = '';
    Provider.of<UserStatus>(context, listen: false).userToken = '';

    Provider.of<AppVersion>(context, listen: false).showContact = true;
  }

  // 本地持久化保存布尔值
  static _saveBool(String key, bool value) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    await prefs.setBool(key, value);
  }

  // 本地持久化保存整型值
  static _saveInt(String key, int value) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    await prefs.setInt(key, value);
  }

  // 本地持久化保存双精度浮点数值
  static _saveDouble(String key, double value) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    await prefs.setDouble(key, value);
  }

  // 本地持久化保存字符串值
  static _saveString(String key, String value) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    await prefs.setString(key, value);
  }
}

/// 用于全局状态持久化存储的键名
class StateKey {
  static const UserName = 'userName';        // 用户名
  static const UserToken = 'userToken';      // 用户登录凭据

  static const ShowContact = 'showContact';  //
}

/// 用户登录全局状态，供Provider用，并带持久化存储
class UserStatus with ChangeNotifier {
  String _userName = '';
  String _userToken = '';

  String get userName => _userName;

  set userName(String value) {
    _userName = value;
    States._saveString(StateKey.UserName, value);
    notifyListeners();
  }

  String get userToken => _userToken;

  set userToken(String value) {
    _userToken = value;
    States._saveString(StateKey.UserToken, value);
    notifyListeners();
  }
}

/// APP版本全局状态，供Provider用，并带持久化存储
class AppVersion with ChangeNotifier {
  String _appVersion = '';
  bool _showContact = true;

  String get appVersion => _appVersion;

  set appVersion(String value) {
    _appVersion = value;
    notifyListeners();
  }

  bool get showContact => _showContact;

  set showContact(bool value) {
    _showContact = value;
    States._saveBool(StateKey.ShowContact, value);
    notifyListeners();
  }
}

/// APP版下载进度状态，供Provider用
class AppDownloadProcess with ChangeNotifier {
  double _process = 0.0;

  double get process => _process;

  set process(double value) {
    _process = value;
    notifyListeners();
  }
}