flutter插件 - shared_preferences（数据存储）

简介

官方文档

数据存储。一个类似于web的localstorage的插件

在关闭app后，并不会自动清除掉值，第二次打开时值还在

使用

• 修改pubspec.yaml文件，添加依赖shared_preferences

# ...
dev_dependencies:
  # ...
  shared_preferences: ^0.5.12
# ...

• 基本使用

SharedPreferences prefs = await SharedPreferences.getInstance();
// 写入字符串
prefs.setString(key, value);
// 读取字符串
prefs.getString(key);
// 删除
prefs.remove(key);
// 清空
prefs.clear();

下面使用单例模式封装一下

• 在lib/utils/目录下新建preference_utils.dart文件

import 'package:shared_preferences/shared_preferences.dart';

class PreferencesKey {
  static const THEME_COLOR_INDEX = 'theme_color_index'; // 当前主题 index
  static const SLIVER_HEADER = 'sliver_header'; // 刷新头部跟随
}

/// shared_preferences 管理类
class PreferenceUtils {
  static PreferenceUtils _instance;

  static PreferenceUtils get instance => PreferenceUtils();

  PreferenceUtils._internal();

  factory PreferenceUtils() {
    if (_instance == null) _instance = PreferenceUtils._internal();
    return _instance;
  }

  saveInteger(String key, int value) => SharedPreferences.getInstance().then((sp) => sp.setInt(key, value));

  saveString(String key, String value) => SharedPreferences.getInstance().then((sp) => sp.setString(key, value));

  saveBool(String key, bool value) => SharedPreferences.getInstance().then((sp) => sp.setBool(key, value));

  saveDouble(String key, double value) => SharedPreferences.getInstance().then((sp) => sp.setDouble(key, value));

  saveStringList(String key, List<String> value) => SharedPreferences.getInstance().then((sp) => sp.setStringList(key, value));

  Future<int> getInteger(String key, [int defaultValue = 0]) async {
    var sp = await SharedPreferences.getInstance();
    var value = sp.getInt(key);
    return value ?? defaultValue;
  }

  Future<String> getString(String key, [String defaultValue = '']) async {
    var sp = await SharedPreferences.getInstance();
    var value = sp.getString(key);
    return value ?? defaultValue;
  }

  Future<bool> getBool(String key, [bool defaultValue = false]) async {
    var sp = await SharedPreferences.getInstance();
    var value = sp.getBool(key);
    return value ?? defaultValue;
  }

  Future<double> getDouble(String key, [double defaultValue = 0.0]) async {
    var sp = await SharedPreferences.getInstance();
    var value = sp.getDouble(key);
    return value ?? defaultValue;
  }

  Future<List<String>> getStringList(String key, [List<String> defaultValue = const <String>[]]) async {
    var sp = await SharedPreferences.getInstance();
    var value = sp.getStringList(key);
    return value ?? defaultValue;
  }
}

• 在lib/config/目录下新建preferences_key.dart

• 在代码中使用

// 设置
PreferenceUtils.instance.saveInteger(PreferencesKey.THEME_COLOR_INDEX, index);

// 获取
PreferenceUtils.instance.getInteger(PreferencesKey.THEME_COLOR_INDEX, 0).then((index) {
  print(index)
});