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Flutter 文件存储详解

news 2026/5/30 21:14:59

Flutter 文件存储详解

一、文件存储概述

Flutter 文件存储用于持久化数据到本地文件系统。常见的存储方式包括 SharedPreferences、Hive、SQFlite 和直接文件操作。

1.1 存储类型

键值存储- SharedPreferences、Hive
关系型数据库- SQFlite
文件存储- 直接读写文件

二、SharedPreferences

2.1 安装依赖

dependencies: shared_preferences: ^2.2.0

2.2 使用示例

import 'package:shared_preferences/shared_preferences.dart'; class StorageService { static late SharedPreferences _prefs; static Future<void> init() async { _prefs = await SharedPreferences.getInstance(); } static String? getString(String key) { return _prefs.getString(key); } static Future<bool> setString(String key, String value) { return _prefs.setString(key, value); } static int? getInt(String key) { return _prefs.getInt(key); } static Future<bool> setInt(String key, int value) { return _prefs.setInt(key, value); } }

三、Hive

3.1 安装依赖

dependencies: hive: ^2.2.3 hive_flutter: ^1.1.0 dev_dependencies: hive_generator: ^1.1.5 build_runner: ^2.4.4

3.2 创建模型

import 'package:hive/hive.dart'; part 'user.g.dart'; @HiveType(typeId: 0) class User extends HiveObject { @HiveField(0) late String name; @HiveField(1) late int age; User({required this.name, required this.age}); }

3.3 生成代码

flutter pub run build_runner build

3.4 使用示例

class HiveService { static late Box<User> _userBox; static Future<void> init() async { await Hive.initFlutter(); Hive.registerAdapter(UserAdapter()); _userBox = await Hive.openBox<User>('users'); } static void addUser(User user) { _userBox.add(user); } static List<User> getUsers() { return _userBox.values.toList(); } }

四、SQFlite

4.1 安装依赖

dependencies: sqflite: ^2.3.0 path: ^1.8.3

4.2 创建数据库

import 'package:sqflite/sqflite.dart'; import 'package:path/path.dart'; class DatabaseHelper { static final DatabaseHelper _instance = DatabaseHelper._internal(); factory DatabaseHelper() => _instance; DatabaseHelper._internal(); static Database? _database; Future<Database> get database async { if (_database != null) return _database!; _database = await _initDatabase(); return _database!; } Future<Database> _initDatabase() async { final path = join(await getDatabasesPath(), 'my_database.db'); return await openDatabase( path, version: 1, onCreate: (db, version) async { await db.execute(''' CREATE TABLE users ( id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, email TEXT NOT NULL UNIQUE ) '''); }, ); } }

五、文件操作

5.1 读取文件

import 'dart:io'; Future<String> readFile(String path) async { final file = File(path); return await file.readAsString(); }

5.2 写入文件

Future<void> writeFile(String path, String content) async { final file = File(path); await file.writeAsString(content); }

5.3 获取应用目录

import 'package:path_provider/path_provider.dart'; Future<String> getApplicationDocumentsDirectory() async { final directory = await getApplicationDocumentsDirectory(); return directory.path; }

六、实战案例

6.1 完整存储服务

class StorageService { static Future<void> saveUser(User user) async { // 使用 SharedPreferences 存储简单数据 final prefs = await SharedPreferences.getInstance(); await prefs.setString('user_name', user.name); // 使用 Hive 存储对象 final box = await Hive.openBox<User>('users'); await box.add(user); } }