Class 省道颤振：为什么终端输出这些线？

达特新手，对我宽容点

我开始研究API，培训的一部分是从API中获取数据。 我创建了一个单独的类来获取数据，并在get time页面中导入它，以便在

initState

中初始化它。 这是我的班级：

import 'dart:convert';
import 'package:http/http.dart';


class WorldTimeClass {
  String flag; // this is the link to a .png flag
  String url; // this is the suffix of the location e.g.: Europe/Berlin
  String time; // this is the time format to be displayed to the user
  String location; // this is the location, say Berlin

  WorldTimeClass({this.flag, this.url, this.time, this.location}); // class object

  Future<String> getData() async { // async method to fetch the data
    Response load = await get('http://worldtimeapi.org/api/timezone/$url');
    Map x(){if(load.statusCode == 200){ // if all goes well, fetch content from API
      print(load.statusCode); // this is so I can see that the operation is successful

    Map map = jsonDecode(load.body); // converting String to MAP
    return map;} // returning Map Object
    else{ // in case of error
      print('No Access');
      return {1:'NoAccess.'};} // had to return a Map Object since I declared Future<Map>
   }

    String datetime = x()['utc_datetime']; // fetching datetime String
    String offsetUTC = x()['utc_offset']; // fetching offset, e.g. +01:00
    DateTime dateTimeObjectConvert = DateTime.parse(datetime);
    // Below converts the datetime string to a DateTime Object and then converts the UTC Offset to a substring only '01' out of +01:00 and then converts it to an int Object and then adds it to the DateTime Object as a Duration (hours);
    dateTimeObjectConvert = dateTimeObjectConvert.add(Duration(hours: int.parse(offsetUTC.substring(1,3))));
    return time = dateTimeObjectConvert.toString(); // returning String to be displayed to user

  }

}

问题：在终端输出中，我得到以下结果：

Restarted application in 1 174ms.
I/flutter (24151): initState..
I/flutter (24151): Instance of 'Future<String>'
I/flutter (24151): 200
I/flutter (24151): 200

在1中重新启动应用程序 174毫秒。
I/颤振（24151）：初始状态。。
I/flatter（24151）：“未来”的实例
I/颤振（24151）：200
I/颤振（24151）：200

问题:

为什么我两次得到代码：200

为什么我会得到“未来”的

实例

以及如何摆脱它

如何在我的终端中打印时间字符串变量

为什么我会得到“未来”的例子，以及如何摆脱它

如何在我的终端中打印时间字符串变量

试着用这种方法从

'Future'

为什么我两次得到代码：200

您的状态代码正在打印两次，因为如果您在此之外打印日志，您的

Map x（）{}

会被调用两次，它将只打印一次

试着用这种方式来争取时间

创建一个pojo类来解析json

class TimeData {
  String abbreviation;
  String client_ip;
  String datetime;
  int day_of_week;
  int day_of_year;
  bool dst;
  int dst_offset;
  int raw_offset;
  String timezone;
  int unixtime;
  String utc_datetime;
  String utc_offset;
  int week_number;

  TimeData(
      {this.abbreviation,
      this.client_ip,
      this.datetime,
      this.day_of_week,
      this.day_of_year,
      this.dst,
      this.dst_offset,
      this.raw_offset,
      this.timezone,
      this.unixtime,
      this.utc_datetime,
      this.utc_offset,
      this.week_number});

  factory TimeData.fromJson(Map<String, dynamic> json) {
    return TimeData(
      abbreviation: json['abbreviation'],
      client_ip: json['client_ip'],
      datetime: json['datetime'],
      day_of_week: json['day_of_week'],
      day_of_year: json['day_of_year'],
      dst: json['dst'],
      dst_offset: json['dst_offset'],
      raw_offset: json['raw_offset'],
      timezone: json['timezone'],
      unixtime: json['unixtime'],
      utc_datetime: json['utc_datetime'],
      utc_offset: json['utc_offset'],
      week_number: json['week_number'],
    );
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['abbreviation'] = this.abbreviation;
    data['client_ip'] = this.client_ip;
    data['datetime'] = this.datetime;
    data['day_of_week'] = this.day_of_week;
    data['day_of_year'] = this.day_of_year;
    data['dst'] = this.dst;
    data['dst_offset'] = this.dst_offset;
    data['raw_offset'] = this.raw_offset;
    data['timezone'] = this.timezone;
    data['unixtime'] = this.unixtime;
    data['utc_datetime'] = this.utc_datetime;
    data['utc_offset'] = this.utc_offset;
    data['week_number'] = this.week_number;

    return data;
  }
}

现在像这样使用

 @override
  void initState() {
    print('initState..');
    super.initState();
    provisionalFunc().then((timeData) => {print(timeData)});
  }

输出

---

因为

字符串datetime=x（）['utc_datetime']；//获取日期时间字符串字符串偏移量utc=x（）['utc_offset']
x（）
twice@dev-aentgs谢谢你，有没有办法叫它一次，但要取两把钥匙？例如，
utc\u datetime
和
utc\u offset
。是的，您已经有了结果，请将其保存在
映射变量中
并访问。像
Map results=x（）；字符串datetime=results['utc_datetime']；字符串offsetUTC=结果['utc_offset']一个调用正在获取所有数据，只需保存并访问它@MehdiRezzagHebla
class TimeData {
  String abbreviation;
  String client_ip;
  String datetime;
  int day_of_week;
  int day_of_year;
  bool dst;
  int dst_offset;
  int raw_offset;
  String timezone;
  int unixtime;
  String utc_datetime;
  String utc_offset;
  int week_number;

  TimeData(
      {this.abbreviation,
      this.client_ip,
      this.datetime,
      this.day_of_week,
      this.day_of_year,
      this.dst,
      this.dst_offset,
      this.raw_offset,
      this.timezone,
      this.unixtime,
      this.utc_datetime,
      this.utc_offset,
      this.week_number});

  factory TimeData.fromJson(Map<String, dynamic> json) {
    return TimeData(
      abbreviation: json['abbreviation'],
      client_ip: json['client_ip'],
      datetime: json['datetime'],
      day_of_week: json['day_of_week'],
      day_of_year: json['day_of_year'],
      dst: json['dst'],
      dst_offset: json['dst_offset'],
      raw_offset: json['raw_offset'],
      timezone: json['timezone'],
      unixtime: json['unixtime'],
      utc_datetime: json['utc_datetime'],
      utc_offset: json['utc_offset'],
      week_number: json['week_number'],
    );
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['abbreviation'] = this.abbreviation;
    data['client_ip'] = this.client_ip;
    data['datetime'] = this.datetime;
    data['day_of_week'] = this.day_of_week;
    data['day_of_year'] = this.day_of_year;
    data['dst'] = this.dst;
    data['dst_offset'] = this.dst_offset;
    data['raw_offset'] = this.raw_offset;
    data['timezone'] = this.timezone;
    data['unixtime'] = this.unixtime;
    data['utc_datetime'] = this.utc_datetime;
    data['utc_offset'] = this.utc_offset;
    data['week_number'] = this.week_number;

    return data;
  }
}

Future<String> getData() async {
    // async method to fetch the data
    Response load = await get('http://worldtimeapi.org/api/timezone/$url');
    print(load.statusCode);

    if (load.statusCode == 200) {
      var timeDate = TimeData.fromJson(json.decode(load.body));
      String datetime = timeDate.utc_datetime; // fetching datetime String
      String offsetUTC = timeDate.utc_offset; // fetching offset, e.g. +01:00
      DateTime dateTimeObjectConvert = DateTime.parse(datetime);
      // Below converts the datetime string to a DateTime Object and then converts the UTC Offset to a substring only '01' out of +01:00 and then converts it to an int Object and then adds it to the DateTime Object as a Duration (hours);
      dateTimeObjectConvert =
          dateTimeObjectConvert.add(Duration(hours: int.parse(offsetUTC.substring(1, 3))));
      return time = dateTimeObjectConvert.toString();
    }else{
      return "No access";
    }

    // returning String to be displayed to user
  }

 @override
  void initState() {
    print('initState..');
    super.initState();
    provisionalFunc().then((timeData) => {print(timeData)});
  }