问如何从UUID类型1中获取日期/时间

EN

private static final long NUM_HUNDRED_NANOS_IN_A_SECOND = 10_000_000L;

private static final long NUM_HUNDRED_NANOS_FROM_UUID_EPOCH_TO_UNIX_EPOCH = 122_192_928_000_000_000L;


/**
 * Extracts the Instant (with the maximum available 100ns precision) from the given time-based (version 1) UUID.
 *
 * @return the {@link Instant} extracted from the given time-based UUID
 * @throws UnsupportedOperationException If this UUID is not a version 1 UUID
 */
public static Instant getInstantFromUUID(final UUID uuid) {
    final long hundredNanosSinceUnixEpoch = uuid.timestamp() - NUM_HUNDRED_NANOS_FROM_UUID_EPOCH_TO_UNIX_EPOCH;
    final long secondsSinceUnixEpoch = hundredNanosSinceUnixEpoch / NUM_HUNDRED_NANOS_IN_A_SECOND;
    final long nanoAdjustment = ((hundredNanosSinceUnixEpoch % NUM_HUNDRED_NANOS_IN_A_SECOND) * 100);
    return Instant.ofEpochSecond(secondsSinceUnixEpoch, nanoAdjustment);
}

import com.fasterxml.uuid.Generators
import com.fasterxml.uuid.NoArgGenerator

class UuidUtil {

    static final NoArgGenerator timeBasedGenerator = Generators.timeBasedGenerator()


    /**
     * From UUID javadocs the resulting timestamp is measured in 100-nanosecond units since midnight, October 15, 1582 UTC
     * timestamp() from UUID is measured in 100-nanosecond units since midnight, October 15, 1582 UTC
     *
     * The Java timestamp in milliseconds since 1970-01-01 as baseline
     *
     * @return
     */
    static long getStartOfUuidRelativeToUnixEpochInMilliseconds () {
        Calendar c = Calendar.getInstance(TimeZone.getTimeZone("GMT-0"))
        c.set(Calendar.YEAR, 1582)
        c.set(Calendar.MONTH, Calendar.OCTOBER)
        c.set(Calendar.DAY_OF_MONTH, 15)
        c.set(Calendar.HOUR_OF_DAY, 0)
        c.set(Calendar.MINUTE, 0)
        c.set(Calendar.SECOND, 0)
        c.set(Calendar.MILLISECOND, 0)

        return c.getTimeInMillis()
    }

    //https://www.wolframalpha.com/input/?i=convert+1582-10-15+UTC+to+unix+time
    final static long START_OF_UUID_RELATIVE_TO_UNIX_EPOCH_SECONDS = -12219292800L
    final static long START_OF_UUID_RELATIVE_TO_UNIX_EPOCH_MILLIS = -12219292800L * 1000L

    /**
     * timestamp() from UUID is measured in 100-nanosecond units since midnight, October 15, 1582 UTC,
     * so we must convert for 100ns units to millisecond procession
     * @param tuid
     * @return
     */
    static long getMillisecondsFromUuid (UUID tuid) {

        assert tuid.version() == 1      //ensure its a time based UUID

        // timestamp returns in 10^-7 (100 nano second chunks), 
        // java Date constructor  assumes 10^-3 (millisecond precision)
        // so we have to divide by 10^4 (10,000) to get millisecond precision  
        long milliseconds_since_UUID_baseline = tuid.timestamp() /10000L

    }

    static getDateFromUuid (UUID tuid) {
        // Allocates a Date object and initializes it to represent the specified number of milliseconds since the 
        // standard java (unix) base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT
        // have to add relative offset from UUID start date of unix epoch to get start date in unix time milliseconds 
        new Date (getMillisecondsFromUuid (tuid) + START_OF_UUID_RELATIVE_TO_UNIX_EPOCH_MILLIS )
    }

    static UUID getTimeBasedUuid () {
        UUID tuid = timeBasedGenerator.generate()
    }

}

println "get start of epoch in milliseconds " + UuidUtil.getStartOfUuidRelativeToUnixEpochInMilliseconds()
assert UuidUtil.START_OF_UUID_RELATIVE_TO_UNIX_EPOCH_MILLIS == UuidUtil.startOfUuidRelativeToUnixEpochInMilliseconds

UUID tuid = UuidUtil.timeBasedUuid

println "uid : $tuid"

Date date = UuidUtil.getDateFromUuid(tuid)
println "extracted date from uid is " + UuidUtil.getDateFromUuid(tuid)

get start of epoch in milliseconds -12219292800000
uid : 43acb588-7d39-11e8-b37b-59f77bf2d333
extracted date from uid is Sun Jul 01 15:15:53 BST 2018

long milliseconds = UuidUtil.extractUnixMilliseconds(uuid);