Hibernate - how to map an EnumSet

问题:

I've a Color Enum

public enum color { GREEN, WHITE, RED } 

and I have MyEntity that contains it.

public class MyEntity {
   private Set<Color> colors;
   ...

I already have a UserType to map my Enums.
Do you know how to map a Set of Enums in the Hibernate hbm.xml?
Do I need a UserType or there's an easiest way?
Thanks

edit: Just to remark, I'm looking for the hbm.xml configuration not the @CollectionOfElements Annotation

回答1:

I use the solution from the EnumSet mapping thread which relies on the use of <element column>. You just need a table with an id and a string to map the collection (MYENTITY_COLOR here). And the mapping looks like that (the EnumUserType is the one from Java 5 EnumUserType):

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <typedef name="color" class="com.stackoverflow.q2402869.EnumUserType">
        <param name="enumClassName">com.stackoverflow.q2402869.Color</param>
    </typedef>
    <class name="com.stackoverflow.q2402869.MyEntity" entity-name="MyEntity" table="MYENTITY">
        <id name="id" type="java.lang.Long">
            <column name="ID" />
            <generator class="assigned" />
        </id>
        <set name="colors" table="MYENTITY_COLORS">
            <key column="ID" not-null="true"/>
            <element type="color" column="COLOR"/>
        </set>
    </class>
</hibernate-mapping>

Query might look like this:

select distinct e from MyEntity e join e.colors colors where colors IN ('WHITE', 'GREEN')

The whole solution works well for loads, saves and queries (credits to jasonab).

回答2:

It seems you need to use the @CollectionOfElements annotation. The doc is at http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#entity-hibspec-collection-extratype, chapter '2.4.6.2.5. Collection of element or composite elements'. The example also maps a Set of Enum.