如何从 flutter 中的 websocket 服务器解析 json 数据？

Question

The WebSocket server is supposed to shoot json data as soon as it goes up, and I want to create a StreamBuilder that updates the data as it shoots me FutureBuilder has received async and wait http.get, and how do I make a Stream for my stream 建造者？

当我从 http 服务器接收信息时，这里是 futurebuilder，（对于所有信息，不是实时的）我想通过流构建器从 websocket 服务器实时接收这样的信息！

class BallInformationWidget extends StatefulWidget {
  @override
  BallInformationWidgetState createState() => BallInformationWidgetState();
}

class BallInformationWidgetState extends State<BallInformationWidget> {
  @override
  Widget build(BuildContext context) {
    return FutureBuilder<List<BallInformation>>(
      future: getHttpBallInfo(urlPrefix),
      builder: (context, snapshot) {
        print('http data : ${snapshot.data}');
        print('http length : ${snapshot.data.length}\n');
        print('http type : ${snapshot.data[0].id.runtimeType}\n');
        BallInformation ballInfo = snapshot.data[0]; // 공하나 객체 선언 후에 for 문?
        return Padding(
          padding: const EdgeInsets.symmetric(vertical: 5.0),
          child: Text(snapshot.hasData ? '${ballInfo.id}' : 'Loading...'),
        );
      },
    );
  }
}

class BallInformation {
  int id;
  double speed;
  String result;
  Map trajectoryParameter;

  BallInformation(this.id, this.speed, this.result, this.trajectoryParameter);

  BallInformation.fromJson(Map<String, dynamic> data) {
    this.id = data['id'];
    this.speed = data['speed'];
    this.result = data['result'];
    this.trajectoryParameter = data['trajectory_parameter'];
  }
}

Future<List<BallInformation>> getHttpBallInfo(String url) async {
  http.Response response = await http.get(url);
  String responseBody = response.body;
  var dataS = json.decode(responseBody);
  List<BallInformation> ballInformation = [];
  // If I receive json(only one information
  ballInformation.add(BallInformation.fromJson(dataS));
  // If I receive json(List, more than 1 information)
  // for (var data in dataS){
  //   ballInformation.add(BallInformation.fromJson(data));
  // }
  return ballInformation;
}

Answer 1

对此的标准方法是json.decode(snapshot.data) 。 这将在请求中返回 json 数据的 map。