Replacing *.hbm.xml files with @Annotations.

[janerikrob]

I have three java classes that are persisted using hibernate. I want to switch from using *.hbm.xml files to annotations on these classes. However the db has additional tables that are created by tags in hbm.xml. Is there a way to create these extra tables using annotations without having to create additional java classes.

One of the java classes that result in two tables in db:

public class Attribute {
     private Long id;

     private String name;

     private String value;

     private VocabularyElement parent;

     // This map will result in its own table using the hbm.xml file listed below.
     // What annotations can I use instead of the hbm.xml file?
     private Map<String, String> extensionAttributes = new HashMap<String, String>();

     // Constructors, getters, setters
     // ...
}

hbm.xml file for the Attribute class:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
     "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
     "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
     <class name="com.tracetracker.mds.adm.domain.Attribute">
         
          <id name="id" access="field">
               <generator class="native"/>
          </id>
         
          <natural-id>
               <property name="name" access="field"/>
               <many-to-one name="parent" class="com.tracetracker.mds.adm.domain.VocabularyElement"/>         
          </natural-id>
         
          <property name="value" type="text"/>
         
          <!-- This tag creates the extra table. -->
          <map name="extensionAttributes" table="Attribute_Attr"
                    order-by="attr_name asc" lazy="false" access="field">
               <key column="id"/>
               <map-key column="attr_name" type="string"/>
               <element column="attr_value" type="string"/>
          </map>
                   
     </class>
</hibernate-mapping>

The resulting sql script:

create table Attribute (

     id int8 not null,
     name varchar(255) not null,
     value text,
     parent int8 not null,
     primary key (id),
     unique (name, parent)
);

create table Attribute_Attr (
     id int8 not null,
     attr_name varchar(255) not null,
     attr_value varchar(255),
     primary key (attr_name, id)
);

alter table Attribute add constraint FK7839CA7C7FB02B5A foreign key (parent) references VocabularyElement;
alter table Attribute_Attr add constraint FK4F4769F4A36A3D31 foreign key (id) references Attribute;

Any help is much apprecated.