Flutter 中时间为 00:00 时如何访问 API？

Question

我正在开发我的第一个 Flutter 应用程序。有一个活动/屏幕显示倒计时时间。我想，当时间是 00:00 时，然后点击 API。

我尝试并搜索它，但我没有找到关于这个问题的最佳信息。 请告诉我如何解决这个问题？ 谢谢。

String get timerString {
    Duration duration = controller.duration * controller.value;
    return '${duration.inMinutes}:${(duration.inSeconds % 60).toString().padLeft(2, '0')}';
  }

  String time;
  String topicName;
  Future<String> getTime() async{
    final response = await http.post(Constant.TestTime,
        body: {
          "topic_id" : widget.valueTopicId,
        });

    Map<String,dynamic> respons = jsonDecode(response.body);

    setState(() {
      time=respons['test_time'];
      topicName=respons['topic_name'];
      controller = AnimationController(
        vsync: this,
        duration: Duration(minutes:int.parse(time) ,seconds: 00),
      );

      if (controller.isAnimating)
        controller.stop();
      else {
        controller.reverse(
            from: controller.value == 0.0
                ? 1.0
                : controller.value);
      }
    });
    print(respons.toString());
    setState(() {
      isLoading=false;
    });
  }


Widget _buildAppBar (BuildContext context){
    return PreferredSize (preferredSize: Size.fromHeight(MediaQuery.of(context).size.height * 0.085),
    child: AppBar(
      backgroundColor: Colors.blue,
      title: Text("Questions"),
      centerTitle: true,
      iconTheme: IconThemeData(
          color: Colors.white
      ),
      actions: <Widget>[
        new Container(
          margin: const EdgeInsets.only(top: 25.0, left: 25.0),
          child: new Text(topicName,
            style: TextStyle(color: Colors.white, fontSize: 26,
                fontWeight: FontWeight.bold),),
        ),
        SizedBox(width: 20),
        new Padding(padding: EdgeInsets.all(20.0)),
        new Padding(padding: EdgeInsets.only(bottom: 40, top: 50)),
        Expanded(
            flex: 1,
            child: Column(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: <Widget>[
                Expanded(
                  child: Align(
                      alignment: FractionalOffset.center,
                      child: AspectRatio(aspectRatio: 1.0,
                        child: Stack(
                          children: <Widget>[
                            Positioned.fill(child:
                            AnimatedBuilder(
                              animation: controller,
                              builder: (BuildContext context,
                                  Widget child) {
                                return Padding(
                                  padding: const EdgeInsets.all(5.0),
                                  child: CustomPaint(
                                    painter: TimerPainter(
                                      animation: controller,
                                      backgroundColor: Colors.white,
                                      color: Colors.blue,
                                    ),
                                  ),
                                );
                              },
                            ),
                            ),
                            Align(
                              alignment: FractionalOffset.center,
                              child: Column(
                                mainAxisAlignment: MainAxisAlignment
                                    .spaceEvenly,
                                crossAxisAlignment: CrossAxisAlignment
                                    .center,
                                children: <Widget>[
                                  AnimatedBuilder(
                                      animation: controller,
                                      builder: (BuildContext context,
                                          Widget child) {
                                        return Text(
                                          timerString, style: TextStyle(
                                            color: Colors.white),
                                        );
                                      }
                                  )
                                ],
                              ),
                            )
                          ],
                        ),
                      )
                  ),
                ),
              ],
            )
        )
      ],
    ) ,);

  }


  @override
  Widget build(BuildContext context) {
    return WillPopScope(
      onWillPop: onBackPressed,
      child: isLoading
          ? Center(child: CircularProgressIndicator(),)
          :MaterialApp(
          debugShowCheckedModeBanner: false,
          home: Scaffold(
            resizeToAvoidBottomPadding: false,
            appBar: _buildAppBar(context),
            body: Questions(widget.valueTopicId,widget.noOfQuestions,widget.difficulty,time),
          )
      ),
    );
  }
}

在这里我发布了我的代码，API getTime() 正在访问 initState()。所以，当我的时间是 00:00 时，应该点击另一个 API。我尝试使用 FutureBuilder 但它没有用。可能是我做错了什么，但在这方面很混乱。

Answer 1

可以使用Timer，需要导入dart:async

Timer(Duration(seconds: 5), () {
  getTime();
});

Answer 2

您需要在initState 中注册您的计时器。 Timer.periodic() 将在指定时间后的特定持续时间内执行。

Timer _timer;

@override
void initState()
{
     _timer = Timer.periodic(
               const Duration(seconds: 1), (Timer t) => handleAPICall(),
            );   
     super.initState();
}

@override
void dispose()
{
    _timer?.cancel();
    super.dispose();
}

void handleAPICall()
{
  // here you need to check if its time to make the API call.
  // I am assuming that you will have some datetime that will tell you 
  // if duration time is 00:00

  if(duration_time == 00:00) // you need to write your correct logic
  {
     // then, make the HTTP Call.
  }      
}