Java – mapping multi-level inheritance in Hibernate

At present, I have such a structure:

A
|
+--B
|
+--C

It uses join tables to map one table per subclass For historical reasons, I also use the discriminator, so the current situation is as shown in section 9.1 3 of the hibernate manual

Question: how to extend the mapping of such a structure:

A
|
+--B
|  |
|  D
|
+--C

Can I map < subclass > < subclass > in Hibernate? What do I need < key >?

Solution

Not tested, but if you are using hibernate 3, according to the link you published

<hibernate-mapping>
  <class name="A" table="A">
    <id name="id" type="long" column="a_id">
      <generator class="native"/>
    </id>
    <discriminator column="discriminator_col" type="string"/>
    <property name="" type=""/>
    <!-- ... -->
  </class>
  <subclass name="B" extends="A" discriminator-value="B">
    <!-- ... -->
  </subclass>
  <subclass name="D" extends="B" discriminator-value="D">
    <!-- ... -->
  </subclass>
  <subclass name="C" extends="A" discriminator-value="C">
    <!-- ... -->
  </subclass>
</hibernate-mapping>