shared_preferences: ^0.5.10 #持久化

import 'dart:convert';

import 'package:shared_preferences/shared_preferences.dart';

///localData 對(duì)外調(diào)用
var localData = LocalData();

///本地?cái)?shù)據(jù)
class LocalData {
  // 工廠方法構(gòu)造函數(shù)
  factory LocalData() => _getInstance();

  // instance的getter方法度迂，singletonManager.instance獲取對(duì)象
  static LocalData get instance => _getInstance();

  // 靜態(tài)變量_instance藤乙，存儲(chǔ)唯一對(duì)象
  static LocalData _instance;

  // 獲取對(duì)象
  static LocalData _getInstance() {
    if (_instance == null) {
      // 使用私有的構(gòu)造方法來創(chuàng)建對(duì)象
      _instance = LocalData._internal();
    }
    return _instance;
  }

  // 私有的自定義命名式構(gòu)造方法，通過它實(shí)現(xiàn)一個(gè)類;
  // 子類不能繼承internal
  // 不是關(guān)鍵字惭墓，可定義其他名字
  LocalData._internal() {
    //初始化(設(shè)置一些默認(rèn)的)...
    _initSharedPreferences();
  }

  ///.....................以上為單例............................

  //SharedPreferences
  static SharedPreferences _preferences;

  ///初始化SharedPreferences
  _initSharedPreferences() async {
    _preferences = await SharedPreferences.getInstance();
  }

  /// 根據(jù)key存儲(chǔ)int類型
  Future<bool> setInt(String key, int value) {
    return _preferences.setInt(key, value);
  }

  /// 根據(jù)key獲取int類型
  int getInt(String key, {int defaultValue = 0}) {
    return _preferences.getInt(key) ?? defaultValue;
  }

  /// 根據(jù)key存儲(chǔ)double類型
  Future<bool> setDouble(String key, double value) {
    return _preferences.setDouble(key, value);
  }

  /// 根據(jù)key獲取double類型
  double getDouble(String key, {double defaultValue = 0.0}) {
    return _preferences.getDouble(key) ?? defaultValue;
  }

  /// 根據(jù)key存儲(chǔ)字符串類型
  Future<bool> setString(String key, String value) {
    return _preferences.setString(key, value);
  }

  /// 根據(jù)key獲取字符串類型
  String getString(String key, {String defaultValue = ""}) {
    return _preferences.getString(key) ?? defaultValue;
  }

  /// 根據(jù)key存儲(chǔ)布爾類型
  Future<bool> setBool(String key, bool value) {
    return _preferences.setBool(key, value);
  }

  /// 根據(jù)key獲取布爾類型
  bool getBool(String key, {bool defaultValue = false}) {
    return _preferences.getBool(key) ?? defaultValue;
  }

  /// 根據(jù)key存儲(chǔ)字符串類型數(shù)組
  Future<bool> setStringList(String key, List<String> value) {
    return _preferences.setStringList(key, value);
  }

  /// 根據(jù)key獲取字符串類型數(shù)組
  List<String> getStringList(String key, {List<String> defaultValue = const []}) {
    return _preferences.getStringList(key) ?? defaultValue;
  }

  /// 根據(jù)key存儲(chǔ)Map類型
  Future<bool> setMap(String key, Map value) {
    return _preferences.setString(key, json.encode(value));
  }

  /// 根據(jù)key獲取Map類型
  Map getMap(String key) {
    String jsonStr = _preferences.getString(key) ?? "";
    return jsonStr.isEmpty ? Map : json.decode(jsonStr);
  }

  //以下為通用方法....

  /// 通用設(shè)置持久化數(shù)據(jù)
  set<T>(String key, T value) {
    String type = value.runtimeType.toString();

    switch (type) {
      case "String":
        setString(key, value as String);
        break;
      case "int":
        setInt(key, value as int);
        break;
      case "bool":
        setBool(key, value as bool);
        break;
      case "double":
        setDouble(key, value as double);
        break;
      case "List<String>":
        setStringList(key, value as List<String>);
        break;
      case "_InternalLinkedHashMap<String, String>":
        setMap(key, value as Map);
        break;
    }
  }

  /// 獲取持久化數(shù)據(jù)
  dynamic get<T>(String key) {
    dynamic value = _preferences.get(key);
    if (value.runtimeType.toString() == "String") {
      if (_isJson(value)) {
        return json.decode(value);
      }
    }
    return value;
  }

  /// 獲取持久化數(shù)據(jù)中所有存入的key
  Set<String> getKeys() {
    return _preferences.getKeys();
  }

  /// 獲取持久化數(shù)據(jù)中是否包含某個(gè)key
  bool containsKey(String key) {
    return _preferences.containsKey(key);
  }

  /// 刪除持久化數(shù)據(jù)中某個(gè)key
  Future<bool> remove(String key) async {
    return await _preferences.remove(key);
  }

  /// 清除所有持久化數(shù)據(jù)
  Future<bool> clear() async {
    return await _preferences.clear();
  }

  /// 重新加載所有數(shù)據(jù),僅重載運(yùn)行時(shí)
  Future<void> reload() async {
    return await _preferences.reload();
  }

  /// 判斷是否是json字符串
  _isJson(String value) {
    try {
      JsonDecoder().convert(value);
      return true;
    } catch (e) {
      return false;
    }
  }
}

參考：
https://blog.csdn.net/Calvin_zhou/article/details/117290861
http://www.reibang.com/p/71260bf0fdbb
https://blog.csdn.net/qq_14876133/article/details/125487330
http://www.reibang.com/p/735b5684e900