Scala 将 DateTime 值转换为时间戳

Question

也许这是一个重复的问题，我试图找到解决方案，但没有办法。

问题:将 DateTime 实例转换为 Timestamp。

我的 DateTime 实例创建为:

    import org.joda.time.DateTime
    val start = (new DateTime).withYear(2016)
       .withMonthOfYear(12)
       .withDayOfMonth(1)
       .withMinuteOfHour(0)
       .withHourOfDay(0)

使用这个日期的 println，我得到:

2016-12-01T00:00:18.856+01:00

我需要的是如下图所示的纪元时间戳:

Answer 1

恕我直言，计算纪元时间戳的最快方法之一是:

scala> :paste
// Entering paste mode (ctrl-D to finish)

def epochDayForYear(year: Int): Long =
  365L * year + (((year + 3) >> 2) - (if (year < 0) {
    val century = year * 1374389535L >> 37 // divide int by 100 (a sign correction is not required)
    century - (century >> 2)
  } else ((year + 99) * 1374389535L >> 37) - ((year + 399) * 1374389535L >> 39))) // divide int by 100 and by 400 accordingly (a sign correction is not required)

def dayOfYearForYearMonth(year: Int, month: Int): Int =
  ((month * 1050835331877L - 1036518774222L) >> 35).toInt - // == (367 * month - 362) / 12
    (if (month <= 2) 0
    else if (isLeap(year)) 1
    else 2)

def isLeap(year: Int): Boolean = (year & 3) == 0 && {
  val century = (year * 1374389535L >> 37).toInt - (year >> 31) // divide int by 100
  century * 100 != year || (century & 3) == 0
}

def secondOfDay(hour: Int, month: Int, day: Int): Int = 
  hour * 3600 + month * 60 + day

val (year, month, day, hour, minute, second, timeZoneOffsetHour, timeZoneOffsetMinute) = 
  (2016, 12, 1, 0, 0, 2, 0, 0)

val epochSecond = 
  (epochDayForYear(year) + (dayOfYearForYearMonth(year, month) + day - 719529)) * 86400 + 
  secondOfDay(hour + timeZoneOffsetHour, minute + timeZoneOffsetMinute, second) // where 719528 is days 0000 to 1970

// Exiting paste mode, now interpreting.

epochDayForYear: (year: Int)Long
dayOfYearForYearMonth: (year: Int, month: Int)Int
isLeap: (year: Int)Boolean
secondOfDay: (hour: Int, month: Int, day: Int)Int
year: Int = 2016
month: Int = 12
day: Int = 1
hour: Int = 0
minute: Int = 0
second: Int = 2
timeZoneOffsetHour: Int = 0
timeZoneOffsetMinute: Int = 0
epochSecond: Long = 1480550402          

顺便说一句，这段代码的大部分是借自 jsoniter-scala项目。