java - 为什么java tzupdater要添加闰秒？

Question

有一些引用文献提到 Java 忽略闰秒:

How can a 1 year old (java) lib correctly perform an UTC Time formatting, considering a newly introduced leap second

Do Java system milliseconds take account of leap seconds?

JDK-4272347 : (cal/tz) support leap seconds ticket

然而文档Timezone Data Versions in the JRE Software提及:

New leap second 2015-06-30 23:59:60 UTC as per IERS Bulletin C 49.

第 3 方 Java 库 Time4J 使用它自己的闰秒列表。

如果Java忽略了闰秒，为什么java的tzupdater工具会添加闰秒？

Answer 1

我现在仔细查看了 TZUPDATER 和 IANA 的发行说明(在其实验位置 github/eggert/tz):

TZUPDATER 说:

The Mexican state of Quintana Roo, represented by America/Cancun, will shift from Central Time with DST to Eastern Time without DST on 2015-02-01 at 02:00. Chile will not change clocks in April or thereafter; its new standard time will be its old daylight saving time. This affects America/Santiago, Pacific/Easter, and Antarctica/Palmer. New leap second 2015-06-30 23:59:60 UTC as per IERS Bulletin C 49.

IANA 表示:

Release 2015a - 2015-01-29 22:35:20 -0800

 Changes affecting future time stamps 

 The Mexican state of Quintana Roo, represented by America/Cancun, 
 will shift from Central Time with DST to Eastern Time without DST 
 on 2015-02-01 at 02:00.  (Thanks to Steffen Thorsen and Gwillim Law.) 

 Chile will not change clocks in April or thereafter; its new standard time 
 will be its old daylight saving time.  This affects America/Santiago, 
 Pacific/Easter, and Antarctica/Palmer.  (Thanks to Juan Correa.) 


 New leap second 2015-06-30 23:59:60 UTC as per IERS Bulletin C 49. 
 (Thanks to Tim Parenti.)

由此看来，Oracle 员工很可能只是进行了复制粘贴操作，而没有过多考虑内容是否与 Java 发行版确实相关。唯一的变化是删除了作者引用。当然，事实仍然是，在实际的 OpenJDK 和 Oracle-Java 发行版中，没有代码或位置可以加载此类闰秒数据。

在我自己的回答中SO-question我还指出了最新的相关mail statement Threeten 项目领导者最终放弃了对闰秒的临时可用计划支持。所以你对 Java-8 的乐观是没有道理的。

顺便说一句，最新版本的 Time4J v2.3 现在可以部署 IANA-TZDB 中包含的闰秒信息，正如您对 TZUPDATER 工具所期望的那样。