Flutter Web从url下载文件而不是打开它

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

class DownloadPage extends StatefulWidget {
  final String fileUrl;

  DownloadPage({required this.fileUrl});

  @override
  _DownloadPageState createState() => _DownloadPageState();
}

class _DownloadPageState extends State<DownloadPage> {
  bool downloading = false;
  String? downloadPath;

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

    final response = await http.get(Uri.parse(widget.fileUrl));
    final documentsDir = await getApplicationDocumentsDirectory();
    final file = File('${documentsDir.path}/downloaded_file.pdf');
    await file.writeAsBytes(response.bodyBytes);

    setState(() {
      downloading = false;
      downloadPath = file.path;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Download File'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            if (downloading)
              CircularProgressIndicator()
            else if (downloadPath != null)
              Text('File downloaded to: $downloadPath')
            else
              ElevatedButton(
                onPressed: downloadFile,
                child: Text('Download File'),
              ),
          ],
        ),
      ),
    );
  }
}