使用 API 获取数据
我的代码
class _MyAppState extends State<MyApp> {
Future<News> news;
@override
void initState() {
super.initState();
news = fetchNews();
}
@override
Widget build(BuildContext context) {
// TODO: implement build
return MaterialApp(
debugShowCheckedModeBanner: false,
home:
Container(
color: Colors.white24,
child:
Center(child:
FutureBuilder<News>(
future: fetchNews(),
builder: (context, snapshot) {
if (snapshot.hasData) {
/* here if I removed toString() it gives me error
The argument type 'News' can't be assigned to the parameter type
'String'. */
return Text(snapshot.data.toString());
} else if (snapshot.hasError) {
return Text("${snapshot.error}");
}
// By default, show a loading spinner.
return CircularProgressIndicator();
},
),
),
)
);
}
}
News newsFromJson(String str) => News.fromJson(json.decode(str));
String newsToJson(News data) => json.encode(data.toJson());
class News {
News({
this.status,
this.totalResults,
this.articles,
});
String status;
int totalResults;
List<Article> articles;
factory News.fromJson(Map<String, dynamic> json) => News(
status: json["status"],
totalResults: json["totalResults"],
articles: List<Article>.from(json["articles"].map((x) => Article.fromJson(x))),
);
Map<String, dynamic> toJson() => {
"status": status,
"totalResults": totalResults,
"articles": List<dynamic>.from(articles.map((x) => x.toJson())),
};
}
class Article {
Article({
this.source,
this.author,
this.title,
this.description,
this.url,
this.urlToImage,
this.publishedAt,
this.content,
});
Source source;
String author;
String title;
String description;
String url;
String urlToImage;
DateTime publishedAt;
String content;
factory Article.fromJson(Map<String, dynamic> json) => Article(
source: Source.fromJson(json["source"]),
author: json["author"] == null ? null : json["author"],
title: json["title"],
description: json["description"] == null ? null : json["description"],
url: json["url"],
urlToImage: json["urlToImage"] == null ? null : json["urlToImage"],
publishedAt: DateTime.parse(json["publishedAt"]),
content: json["content"],
);
Map<String, dynamic> toJson() => {
"source": source.toJson(),
"author": author == null ? null : author,
"title": title,
"description": description == null ? null : description,
"url": url,
"urlToImage": urlToImage == null ? null : urlToImage,
"publishedAt": publishedAt.toIso8601String(),
"content": content,
};
}
class Source {
Source({
this.id,
this.name,
});
dynamic id;
String name;
factory Source.fromJson(Map<String, dynamic> json) => Source(
id: json["id"],
name: json["name"],
);
Map<String, dynamic> toJson() => {
"id": id,
"name": name,
};
}
Future<News> fetchNews() async {
final response = await http.get('My-Api');
if (response.statusCode == 200) {
return News.fromJson(jsonDecode(response.body));
} else {
throw Exception('Failed to load album');
}
}
当我运行此代码时，输出是：“新闻”的实例
我搜索了互联网，发现大多数解决方案都说我必须添加等待。
唯一的问题是他们没有说我应该把它准确地放在代码中的什么地方
您的帮助将不胜感激，
谢谢
注意：我还是个初学者