Package com.fasterxml.uuid.impl

Class TimeBasedEpochRandomGenerator

java.lang.Object
com.fasterxml.uuid.UUIDGenerator
com.fasterxml.uuid.NoArgGenerator
com.fasterxml.uuid.impl.TimeBasedEpochRandomGenerator
public class TimeBasedEpochRandomGenerator extends NoArgGenerator
Implementation of UUID generator that uses time/location based generation method field from the Unix Epoch timestamp source - the number of milliseconds seconds since midnight 1 Jan 1970 UTC, leap seconds excluded. This is usually referred to as "Version 7". In addition to that random part is regenerated for every new UUID. This removes possibilities to have almost similar UUID, when calls to generate are made within same millisecond.

As all JUG provided implementations, this generator is fully thread-safe. Additionally it can also be made externally synchronized with other instances (even ones running on other JVMs); to do this, use FileBasedTimestampSynchronizer (or equivalent).

Since:
5.0

  • Field Details

    • _random

      protected final Random _random
      Random number generator that this generator uses.

    • _clock

      protected final UUIDClock _clock
      Underlying UUIDClock used for accessing current time, to use for generation.

  • Constructor Details

    • TimeBasedEpochRandomGenerator

      public TimeBasedEpochRandomGenerator(Random rnd)
      Parameters:
      rnd - Random number generator to use for generating UUIDs; if null, shared default generator is used. Note that it is strongly recommend to use a good (pseudo) random number generator; for example, JDK's SecureRandom.

    • TimeBasedEpochRandomGenerator

      public TimeBasedEpochRandomGenerator(Random rnd, UUIDClock clock)
      Parameters:
      rnd - Random number generator to use for generating UUIDs; if null, shared default generator is used. Note that it is strongly recommend to use a good (pseudo) random number generator; for example, JDK's SecureRandom.
      clock - clock Object used for accessing current time to use for generation

  • Method Details

    • getType

      public UUIDType getType()
      Description copied from class: UUIDGenerator
      Accessor for determining type of UUIDs (version) that this generator instance will produce.
      Specified by:
      getType in class UUIDGenerator

    • generate

      public UUID generate()
      Description copied from class: NoArgGenerator
      Method for generating a UUID.
      Specified by:
      generate in class NoArgGenerator
      Returns:
      Newly generated UUID

    • construct

      public UUID construct(long rawTimestamp)
      Method that will construct actual UUID instance for given unix epoch timestamp: called by generate() but may alternatively be called directly to construct an instance with known timestamp. NOTE: calling this method directly produces somewhat distinct UUIDs as "entropy" value is still generated as necessary to avoid producing same UUID even if same timestamp is being passed.
      Parameters:
      rawTimestamp - unix epoch millis
      Returns:
      unix epoch time based UUID