I\'m trying to create a custom way of computing and passing unique id\'s that follow my own pattern.
Hibernate has the @GenericGenerator annotation that lets you map
No, it doesn't have. Only possibility without 3rd party is to assign value by yourself. If you want to save yourself from calling method that sets id, then for example Prepersist callback can be used.
@PrePersist
public void ensureId() {
id = ...
}
If you are using EclipseLink, you can define your own custom Sequence object.
http://wiki.eclipse.org/EclipseLink/Examples/JPA/CustomSequencing
JPA 2.0 does not define a custom sequence generator, but JPA 2.1 does define a Converter API, which may be of use.