如何将时间转换为UTC，然后转换为设备本地时间 [英] How to convert a time to UTC and then device local time

问题描述

我正在从服务中获取时间

I am getting following time from service

'2019年11月11日晚上7:30'

'Nov 11 2019 7:30 PM'

我知道这是美国中部时间，我需要获取当前时间与该事件时间之间的小时数，但是我无法理解如何将该日期转换为UTC.

I know this is US Central Time, I need to get hours between current time and this event time, but i am unable to understand how to convert this date to UTC.

我正在使用以下方法，但这似乎无法正常工作.

I am using following approach, but this does not seem to be working fine.

   public Date ticketJSONDateFormatter(String dateTime){

            SimpleDateFormat simpleDateFormatter = new SimpleDateFormat("MMM d yyyy HH:mm a");

            Date parsedDate= null;
            try {

                simpleDateFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
                parsedDate= simpleDateFormatter.parse(dateTime);

           } catch (ParseException e) {
                e.printStackTrace();
            }

            return parsedDate;
        }   

此方法返回date

Fri Oct 11 12:30:00 GMT+05:00 2019

尽管预期的输出可能是这样的.我的设备位于(+5:00 UTC)

Although the expected output may be something like this. My device is at (+5:00 UTC)

Fri Oct 12 12:30:00 GMT+05:00 2019

推荐答案

您可以按照以下步骤操作:

You can get this in following steps:

1. 使用
2. 获取您的当前时间.
3. 查找当前时间与转换为本地时间的事件时间之间的时差.

1. Use ZonedDateTime.parse to parse the time you are receiving.
2. Convert the America Central time to your local time.
3. Get your current time.
4. Find the difference between your current time and the event time converted to your local.

示例:

    // Parsing the time you are receiving in Central Time Zone. Using Chicago as a representative Zone.
    String dateWithZone = "Nov 11 2019 7:30 PM".concat("America/Chicago") ;
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMM dd uuuu h:m aVV");

    ZonedDateTime zonedDateTime = ZonedDateTime.parse(dateWithZone, formatter);
    System.out.println(zonedDateTime); // This is the time you received in Central time zone.

    // Now convert the event time in your local time zone
    ZonedDateTime eventTimeInLocal = zonedDateTime.withZoneSameInstant(ZoneId.systemDefault());

    // Then find the duration between your current time and event time
    System.out.println(Duration.between(ZonedDateTime.now(), eventTimeInLocal).toHours());

duration类提供了许多其他实用程序方法来获得更精确的持续时间.

The duration class provides many other utilities methods to get more precise duration.

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