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dart - 如何在特定时区创建 DateTime 实例？

问题描述

我正在调用一个遗留服务，它以字符串格式返回所有时间，假设时区是 EST。如何创建 DateTime 实例并指定时区为 EST？当我向用户显示时间时，我将转换为他们的设备时区。

标签： dart

解决方案

我为此写了一个包。它称为 Instant，它可以获取全球任何给定区域中的最新 DateTime。详细看一下https://aditya-kishore.gitbook.io/instant/

在时区中获取 DateTime 的基本用法相当简单。

注意：我在下面假设您的旧服务在 24 小时内提供格式为 HH:MM 的字符串，并且它不提供日期。如果以下任何一项不正确，请让我知道，我将更改代码示例。

List<int> _hourmin (String parse) {
  List<int> timeinint = [];
  if (parse.length == 5) {
    //if parse is something like 10:00
    timeinint.add(int.parse(parse.substring(0,2))); //Add hours (10)
    timeinint.add(int.parse(parse.substring(3,5))); //Add minutes (0)
  } //hours >= 10
  if (parse.length == 4) {
    //if parse is something like 4:06
    timeinint.add(int.parse(parse.substring(0,1))); //Add hours (4)
    timeinint.add(int.parse(parse.substring(2,4))); //Add minutes (6)
  } //hours < 10
  return timeinint;
}

DateTime utcDateTimeFromZone(
    {@required String zone,
    int year = 0,
    int month = 0,
    int day = 0,
    int hour = 0,
    int minute = 0,
    int second = 0,
    int millisecond = 0,
    int microsecond = 0}) {

  hour = (hour - timeZoneOffsets[zone].truncate()) % 24; //Convert to UTC from timezone
  if (hour<0) {
    hour = 24 + hour;
  }
  minute = (minute - ((timeZoneOffsets[zone]%1)*60).round()) % 60;
  if (minute<0) {
    minute = 60 + minute;
  }
//Convert to UTC from timezone
  DateTime inUTC = DateTime.utc(year, month, day, hour, minute, second, millisecond, microsecond); //Initialize in UTC time
  return inUTC;
}

  //We get an array containing the hours minutes
  List<int> time = _hourmin("4:25"); //put your API call as the param here
  //This is what you need
  DateTime finished = utcDateTimeFromZone(zone: "EST", hour: time[0], minute: time[1]);

  print(formatTime(time: finished.toLocal())); //1:25 for me, because I'm PST, but this works with any local timezone

希望清除它！

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