基于LocalDateTime创建ZonedDateTime实例的java问题
我看到一些我无法解释的行为,希望有人能给我指出正确的方向
我首先创建一个LocalDateTime实例,然后通过将“Europe/London”时区应用于LocalDateTime来获得ZoneDateTime,然后使用DateTimeFormatter打印输出。我希望看到与LocalDateTime实例中指定的时间完全相同的时间,但在下面的示例中,zonedDateTimeBeforeDST_Original的输出比我预期的要晚一个小时
那么,简而言之:为什么我的LocalDateTime中的01:55变成了ZoneDateTime中的02:55
仅供参考,在其他时区没有看到这种行为。伦敦的那个似乎是个特例
//init date pattern
final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
final DateTimeFormatter formatterOut = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss XXX");
LocalDateTime localDateTimeBeforeDST = LocalDateTime.parse("2018-03-25 01:55:00", formatter); //testing with time 5 minutes before DST switch or after
System.out.println("LocalDateTime: " + localDateTimeBeforeDST.format(formatter));
System.out.println();
String originalZone = "Europe/London";
ZoneId originalZoneId = ZoneId.of(originalZone);
ZoneId utcZoneId = ZoneId.of("Etc/UTC");
ZoneId localZoneId = ZoneId.of("Europe/London");
ZoneId localZoneId_2 = ZoneId.of("Europe/Brussels");
ZonedDateTime zonedDateTimeBeforeDST_Original = localDateTimeBeforeDST.atZone(originalZoneId);
ZonedDateTime zonedDateTimeBeforeDST_UTC = zonedDateTimeBeforeDST_Original.withZoneSameInstant(utcZoneId);
ZonedDateTime zonedDateTimeBeforeDST_1 = zonedDateTimeBeforeDST_UTC.withZoneSameInstant(localZoneId);
ZonedDateTime zonedDateTimeBeforeDST_2 = zonedDateTimeBeforeDST_UTC.withZoneSameInstant(localZoneId_2);
System.out.println("Instant: " + zonedDateTimeBeforeDST_Original.toEpochSecond());
System.out.println();
System.out.println("ZonedDateTime (" + originalZone + "): " + zonedDateTimeBeforeDST_Original.format(formatterOut));
System.out.println("ZonedDateTime (Etc/UTC): " + zonedDateTimeBeforeDST_UTC.format(formatterOut));
System.out.println("ZonedDateTime (Europe/London): " + zonedDateTimeBeforeDST_1.format(formatterOut));
System.out.println("ZonedDateTime (Europe/Brussels): " + zonedDateTimeBeforeDST_2.format(formatterOut));
System.out.println();
zonedDateTimeBeforeDST_Original = zonedDateTimeBeforeDST_Original.plus(10, ChronoUnit.MINUTES);
zonedDateTimeBeforeDST_UTC = zonedDateTimeBeforeDST_Original.withZoneSameInstant(utcZoneId);
zonedDateTimeBeforeDST_1 = zonedDateTimeBeforeDST_UTC.withZoneSameInstant(localZoneId);
zonedDateTimeBeforeDST_2 = zonedDateTimeBeforeDST_UTC.withZoneSameInstant(localZoneId_2);
System.out.println("ZonedDateTime (DST) (" + originalZone + "): " + zonedDateTimeBeforeDST_Original.format(formatterOut));
System.out.println("ZonedDateTime (DST) (Etc/UTC): " + zonedDateTimeBeforeDST_UTC.format(formatterOut));
System.out.println("ZonedDateTime (DST) (Europe/London): " + zonedDateTimeBeforeDST_1.format(formatterOut));
System.out.println("ZonedDateTime (DST) (Europe/Brussels): " + zonedDateTimeBeforeDST_2.format(formatterOut));
输出:
LocalDateTime: 2018-03-25 01:55:00
Instant: 1521942900
ZonedDateTime (Europe/London): 2018-03-25 02:55:00 +01:00
ZonedDateTime (Etc/UTC): 2018-03-25 01:55:00 Z
ZonedDateTime (Europe/London): 2018-03-25 02:55:00 +01:00
ZonedDateTime (Europe/Brussels): 2018-03-25 03:55:00 +02:00
ZonedDateTime (DST) (Europe/London): 2018-03-25 03:05:00 +01:00
ZonedDateTime (DST) (Etc/UTC): 2018-03-25 02:05:00 Z
ZonedDateTime (DST) (Europe/London): 2018-03-25 03:05:00 +01:00
ZonedDateTime (DST) (Europe/Brussels): 2018-03-25 04:05:00 +02:00
# 1 楼答案
这是夏季(DST)的问题。当英国的夏季开始,时钟从1转为2时,没有2018-03-25 01:55:00
ZonedDateTime
没有给你一个不存在的时间,所以它选择了一个存在的时间它选择的确切时间在the documentation of ^{} 中指定:
当然,在使用夏季的其他时区也会发生同样的事情。只有每个时区有自己的过渡时间,通常与2018年3月25日星期日01:00不一致