Flutter shared_preferences Use

sketch

Encapsulate platform specific persistent storage for simple data (iOS and macOS Upper NSUserDefaults, Android Upper SharedPreferences, wait ). Data may be persisted asynchronously to disk , And there is no guarantee that the write will be persisted to the disk after it is returned , So this plug-in cannot be used to store key data .

Add dependency

shared_preferences: ^2.0.15

Basic use

Support data types

int, double, bool, String and List<String>.

Support platform

iOS： NSUserDefaults
Android： SharedPreferences
Web： localStorage
Linux： FileSystem（ Save data to the local system file library ）
Mac OS： FileSystem（ Save data to the local system file library ）
Windows： FileSystem（ Save data to the local system file library ）

Writing data

var sp = await SharedPreferences.getInstance();
sp.setString("name", " Xiao Ming ");
sp.setInt("age", 18);
sp.setBool("sex", true);
sp.setDouble("height", 180.1);
sp.setStringList("address", <String>[" The Beijing municipal ", " Haidian District "]);

Reading data

var sp = await SharedPreferences.getInstance();
String? name = sp.getString("name");
int? age = sp.getInt("age");
bool? sex = sp.getBool("sex");
double? height = sp.getDouble("height");
List<String>? address = sp.getStringList("address");

Delete data

Delete a data

var sp = await SharedPreferences.getInstance();
sp.remove("name");

Clear all data

var sp = await SharedPreferences.getInstance();
sp.clear();

Get all key

var sp = await SharedPreferences.getInstance();
var keys = sp.getKeys();

key Whether there is

var sp = await SharedPreferences.getInstance();
var b = sp.containsKey("name");

encapsulation

Encapsulates the code

import 'dart:convert';

import 'package:shared_preferences/shared_preferences.dart';

class SpUtils {
    SpUtils._internal();

    factory SpUtils() => _instance;

    static late final SpUtils _instance = SpUtils._internal();

    static late SharedPreferences _preferences;

    static Future<SpUtils> getInstance() async {
        _preferences = await SharedPreferences.getInstance();
        return _instance;
    }

    ///  according to key Storage int type 
    static Future<bool> setInt(String key, int value) {
        return _preferences.setInt(key, value);
    }

    ///  according to key obtain int type 
    static int? getInt(String key, {int defaultValue = 0}) {
        return _preferences.getInt(key) ?? defaultValue;
    }

    ///  according to key Storage double type 
    static Future<bool> setDouble(String key, double value) {
        return _preferences.setDouble(key, value);
    }

    ///  according to key obtain double type 
    static double? getDouble(String key, {double defaultValue = 0.0}) {
        return _preferences.getDouble(key) ?? defaultValue;
    }

    ///  according to key Storage string type 
    static Future<bool> setString(String key, String value) {
        return _preferences.setString(key, value);
    }

    ///  according to key Get string type 
    static String? getString(String key, {String defaultValue = ""}) {
        return _preferences.getString(key) ?? defaultValue;
    }

    ///  according to key Store Boolean types 
    static Future<bool> setBool(String key, bool value) {
        return _preferences.setBool(key, value);
    }

    ///  according to key Get boolean type 
    static bool? getBool(String key, {bool defaultValue = false}) {
        return _preferences.getBool(key) ?? defaultValue;
    }

    ///  according to key Store an array of string types 
    static Future<bool> setStringList(String key, List<String> value) {
        return _preferences.setStringList(key, value);
    }

    ///  according to key Gets an array of string types 
    static List<String> getStringList(String key, {List<String> defaultValue = const []}) {
        return _preferences.getStringList(key) ?? defaultValue;
    }

    ///  according to key Storage Map type 
    static Future<bool> setMap(String key, Map value) {
        return _preferences.setString(key, json.encode(value));
    }

    ///  according to key obtain Map type 
    static Map getMap(String key) {
        String jsonStr = _preferences.getString(key) ?? "";
        return jsonStr.isEmpty ? Map : json.decode(jsonStr);
    }

    ///  Common settings persist data 
    static 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;
        }
    }

    ///  Get persistent data 
    static dynamic get<T>(String key) {
        dynamic value = _preferences.get(key);
        if (value.runtimeType.toString() == "String") {
            if (_isJson(value)) {
                return json.decode(value);
            }
        }
        return value;
    }

    ///  Get all stored data in the persistent data key
    static Set<String> getKeys() {
        return _preferences.getKeys();
    }

    ///  Gets whether the persistent data contains a key
    static bool containsKey(String key) {
        return _preferences.containsKey(key);
    }

    ///  Delete one of the persistent data key
    static Future<bool> remove(String key) async {
        return await _preferences.remove(key);
    }

    ///  Clear all persistent data 
    static Future<bool> clear() async {
        return await _preferences.clear();
    }

    ///  Reload all data , Reload runtime only 
    static Future<void> reload() async {
        return await _preferences.reload();
    }

    ///  Judge whether it is json character string 
    static _isJson(String value) {
        try {
            JsonDecoder().convert(value);
            return true;
        } catch (e) {
            return false;
        }
    }
}

initialization

void main() async {
    WidgetsFlutterBinding.ensureInitialized();
    await SpUtils.getInstance();
}

Usage 1

Writing data ：

SpUtils.setString("name", " Xiao Ming 2");
SpUtils.setInt("age", 28);
SpUtils.setBool("sex", true);
SpUtils.setDouble("height", 180.2);
SpUtils.setStringList("address", <String>[" The Beijing municipal 2", " Haidian District 2"]);

Reading data ：

String? name = SpUtils.getString("name");
int? age = SpUtils.getInt("age");
bool? sex = SpUtils.getBool("sex");
double? height = SpUtils.getDouble("height");
List<String>? address = SpUtils.getStringList("address");

Mode 2

Writing data ：

SpUtils.set("name", " Xiao Ming 3");
SpUtils.set("age", 38);
SpUtils.set("sex", true);
SpUtils.set("height", 180.3);
SpUtils.set("address", <String>[" The Beijing municipal 3", " Haidian District 3"]);

Reading data ：

String? name = SpUtils.get<String>("name");
int? age = SpUtils.get<int>("age");
bool? sex = SpUtils.get<bool>("sex");
double? height = SpUtils.get<double>("height");
List<String>? address = SpUtils.get<List<String>>("address");