Java转换UTC/CET时间

Question

我想将给定的日期时间(它是 utc 日期时间)转换为 CET 中相应的日期时间，并正确映射欧洲夏令时/冬令时(夏令时)。我设法使用 java.time 相反(CET 到 UTC) :

public static LocalDateTime cetToUtc(LocalDateTime timeInCet) {
    ZonedDateTime cetTimeZoned = ZonedDateTime.of(timeInCet, ZoneId.of("CET"));
    return cetTimeZoned.withZoneSameInstant(ZoneOffset.UTC).toLocalDateTime();
}

但我没有反其道而行之:

public static LocalDateTime utcToCet(LocalDateTime timeInUtc) {
     ZonedDateTime cetTimeZoned = ZonedDateTime.of(timeInUtc,ZoneId.of("UTC"));
     return cetTimeZoned.withZoneSameInstant(ZoneOffset.of(???)).toLocalDateTime(); // what to put here?
 }

我怎样才能做到这一点？

Answer 1

只需使用 ZoneId.of("CET")

import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;

public class Main {

    public static void main(String args[])
    {
        LocalDateTime date = LocalDateTime.now(ZoneId.of("CET"));
        System.out.println(date);

        LocalDateTime utcdate = cetToUtc(date);
        System.out.println(utcdate);

        LocalDateTime cetdate = utcToCet(utcdate);
        System.out.println(cetdate);
    }

    public static LocalDateTime cetToUtc(LocalDateTime timeInCet) {
        ZonedDateTime cetTimeZoned = ZonedDateTime.of(timeInCet, ZoneId.of("CET"));
        return cetTimeZoned.withZoneSameInstant(ZoneOffset.UTC).toLocalDateTime();
    }

    public static LocalDateTime utcToCet(LocalDateTime timeInUtc) {
         ZonedDateTime utcTimeZoned = ZonedDateTime.of(timeInUtc,ZoneId.of("UTC"));
         return utcTimeZoned.withZoneSameInstant(ZoneId.of("CET")).toLocalDateTime();
     }
}