如何在flutter中将文件从firebase下载到本地手机存储？

import 'package:flutter/material.dart';
import 'package:firebase_storage/firebase_storage.dart' as firebase_storage;
import 'package:path_provider/path_provider.dart';

class FileDownloadScreen extends StatefulWidget {
  @override
  _FileDownloadScreenState createState() => _FileDownloadScreenState();
}

class _FileDownloadScreenState extends State<FileDownloadScreen> {
  final String fileUrl = 'your_file_url'; // 替换为要下载的文件的URL
  bool downloading = false;

  Future<void> downloadFile() async {
    setState(() {
      downloading = true;
    });

    try {
      firebase_storage.Reference ref =
          firebase_storage.FirebaseStorage.instance.refFromURL(fileUrl);

      final String fileName = ref.name;
      final Directory appDir = await getApplicationDocumentsDirectory();
      final String filePath = '${appDir.path}/$fileName';

      await ref.writeToFile(File(filePath));

      setState(() {
        downloading = false;
      });

      print('文件已下载到本地存储：$filePath');
    } catch (e) {
      print('文件下载失败：$e');
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('文件下载'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            if (downloading)
              CircularProgressIndicator()
            else
              ElevatedButton(
                onPressed: downloadFile,
                child: Text('下载文件'),
              ),
          ],
        ),
      ),
    );
  }
}