如何使用Flutter和sqflite从文件开始加载应用程序中的数据？

dependencies:
  sqflite: ^x.x.x

import 'package:sqflite/sqflite.dart';
import 'package:path/path.dart';

class DatabaseHelper {
  static final DatabaseHelper _instance = DatabaseHelper.internal();
  factory DatabaseHelper() => _instance;

  static Database? _database;

  Future<Database?> get database async {
    if (_database != null) return _database;
    _database = await initDatabase();
    return _database;
  }

  DatabaseHelper.internal();

  Future<Database> initDatabase() async {
    String databasesPath = await getDatabasesPath();
    String path = join(databasesPath, 'my_database.db');
    return await openDatabase(
      path,
      version: 1,
      onCreate: _onCreate,
    );
  }

  void _onCreate(Database db, int version) async {
    await db.execute('CREATE TABLE my_table (id INTEGER PRIMARY KEY, name TEXT)');
  }
}

import 'package:flutter/material.dart';
import 'package:path/path.dart';
import 'package:sqflite/sqflite.dart';

class DataPage extends StatefulWidget {
  @override
  _DataPageState createState() => _DataPageState();
}

class _DataPageState extends State<DataPage> {
  List<Map<String, dynamic>> _dataList = [];

  @override
  void initState() {
    super.initState();
    loadData();
  }

  Future<void> loadData() async {
    Database? database = await openDatabase(
      join(await getDatabasesPath(), 'my_database.db'),
    );
    List<Map<String, dynamic>> dataList = await database.query('my_table');
    setState(() {
      _dataList = dataList;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Data Page'),
      ),
      body: ListView.builder(
        itemCount: _dataList.length,
        itemBuilder: (context, index) {
          return ListTile(
            title: Text(_dataList[index]['name']),
          );
        },
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'data_page.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: HomePage(),
      routes: {
        '/data': (context) => DataPage(),
      },
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home Page'),
      ),
      body: Center(
        child: ElevatedButton(
          child: Text('Load Data'),
          onPressed: () {
            Navigator.pushNamed(context, '/data');
          },
        ),
      ),
    );
  }
}