如何从firebase获取数据(如包含url、inkwell对象和字符串的新闻文章)到flutter应用程序中？

import 'package:firebase_database/firebase_database.dart';

class NewsArticle {
  final String title;
  final String url;
  final String imageUrl;

  NewsArticle({required this.title, required this.url, required this.imageUrl});
}

class NewsScreen extends StatefulWidget {
  @override
  _NewsScreenState createState() => _NewsScreenState();
}

class _NewsScreenState extends State<NewsScreen> {
  final DatabaseReference _database = FirebaseDatabase.instance.reference();

  List<NewsArticle> _newsArticles = [];

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

  void _fetchNewsArticles() {
    _database.child('news_articles').once().then((DataSnapshot snapshot) {
      Map<dynamic, dynamic> articles = snapshot.value;
      articles.forEach((key, value) {
        String title = value['title'];
        String url = value['url'];
        String imageUrl = value['imageUrl'];

        NewsArticle article = NewsArticle(
          title: title,
          url: url,
          imageUrl: imageUrl,
        );

        setState(() {
          _newsArticles.add(article);
        });
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('News'),
      ),
      body: ListView.builder(
        itemCount: _newsArticles.length,
        itemBuilder: (context, index) {
          NewsArticle article = _newsArticles[index];
          return ListTile(
            title: Text(article.title),
            subtitle: Text(article.url),
            leading: Image.network(article.imageUrl),
          );
        },
      ),
    );
  }
}