flutter - Flutter 不在列表视图中显示视频

Question

抱歉在这里问了一个愚蠢的问题。我是 Flutter 的新手，我正在开发一个小型 Flutter 应用程序，它可以获取 json 并在 ListView 中显示视频。

但它是空白的，并且没有在应用程序中显示任何视频。

Future<Photo> fetchJson() async {
  var url = "https://api.tenor.com/v1/random?key=1FS646G91JAT&q=meme&media_filter=basic&limit=50";
  var response = await http.get(url);

  if (response.statusCode == 200) {
    return photoFromJson(response.body);
  } else {
    throw Exception('Failed to fetch json');
  }
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Multiple Videos Decode Test'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title, this.url}) : super(key: key);

  final String title;
  final String url;

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

class _MyHomePageState extends State<MyHomePage> {
  Future<Photo> futureJson;

  String url;

  VideoPlayerController _controller;
  Future<void> _initializeVideoPlayerFuture;

  @override
  void initState() {
    futureJson = fetchJson();
    _controller = VideoPlayerController.network(widget.url);

    _initializeVideoPlayerFuture = _controller.initialize();
    _controller.setLooping(true);

    super.initState();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Container(
        child: FutureBuilder<Photo>(
            future: futureJson,
            builder: (context, snapshot) {
              if (snapshot.hasError) {
                return Container(
                    child:Center(
                        child: Text("${snapshot.error}")
                    )
                );
              } else if(snapshot.hasData) {
                return ListView.builder(
                    itemCount: snapshot.data.results.length,
                    itemBuilder: (context, index){
                      var url = snapshot.data.results[index].media[0].mp4.url;
                      return FutureBuilder(
                        future: _initializeVideoPlayerFuture,
                        builder: (context, snapshot2){
                          if(snapshot2.connectionState == ConnectionState.done){
                            return AspectRatio(
                              aspectRatio: _controller.value.aspectRatio,
                              child: VideoPlayer(_controller = VideoPlayerController.network(url),
                              ),
                            );
                          } else {
                            return Center(
                                child: CircularProgressIndicator()
                            );
                          }
                        },
                      );
                    });}
              return Center(
                  child: CircularProgressIndicator()
              );
            }
        ),
      ),
    );
  }
}

没有错误，我认为问题可能是

_controller = VideoPlayerController.network(widget.url);

但是我如何将 url 链接发送到视频播放器？寻求帮助，谢谢。