如何在 Scala 中将日期格式转换为 UTC？

Question

How to convert date format "2021-02-28 13:38:00.597+0000" to "Mon, Feb 28,2021 15:25:00 UTC" UTC format in Scala?

Answer 1

If you could use java.time , you would need

• a DateTimeFormatter for parsing String s with the format of your input example, which is quite near to ISO standard, but is missing the 'T' between date and time of day
• another DateTimeFormatter for outputting the temporal content in the desired format, which includes (English) abbreviations for day of week and month of year
• an OffsetDateTime for parsing the String with the first DateTimeFormatter and
• a ZonedDateTime for the temporal value in UTC

This is how I would do it in Java:

public static void main(String[] args) {
    // example String
    String utcDatetimeString = "2021-02-28 13:38:00.597+0000";
    // prepare a formatter that can parse a String of this format
    DateTimeFormatter dtfIn = DateTimeFormatter.ofPattern(
                                        "uuuu-MM-dd HH:mm:ss.SSSxxxx",
                                        Locale.ENGLISH
                                    );
    // parse it to an OffsetDateTime
    OffsetDateTime odt = OffsetDateTime.parse(utcDatetimeString, dtfIn);
    // then convert it to a ZonedDateTime applying UTC zone
    ZonedDateTime zdt = odt.atZoneSameInstant(ZoneId.of("UTC"));
    // prepare a formatter that produces the desired output
    DateTimeFormatter dtfOut = DateTimeFormatter.ofPattern(
                                        "EEE, MMM dd, uuuu HH:mm:ss zzz",
                                        Locale.ENGLISH
                                    );
    // and print the ZonedDateTime using the formatter
    System.out.println(zdt.format(dtfOut));
}

Output:

Sun, Feb 28, 2021 13:38:00 UTC

Answer 2

You can use the DateTimeFormat from joda-time. You have not mentioned a time zone at all, and using my time zone would give a different hour, so I used UTC for the first date as well. You can adjust that to your time zone:

  val OldFormat = "yyyy-MM-dd HH:mm:ss.SSSZ"
  val NewFormat = "EEE, MMM dd,yyyy HH:mm:ss z"

  val oldDateString = "2021-02-28 13:38:00.597+0000"

  val formatterOld  = DateTimeFormat.forPattern(OldFormat)
  val formatterNew  = DateTimeFormat.forPattern(NewFormat)
  val dateTime      = formatterOld.withZoneUTC().parseDateTime(oldDateString)
  val newDateString = formatterNew.withZoneUTC().print(dateTime)
  println(dateTime)     // 2021-02-28T13:38:00.597Z
  println(newDateString) // Sun, Feb 28,2021 13:38:00 UTC