Below is an example.

The parent class:

—-
import java.io.Serializable;
import java.math.BigDecimal;

/**
* @hibernate.class
* table=”ANIMAL”
*/
public class Animal implements Serializable {
private BigDecimal myId;
private String myAge;

public Animal() {
}

/**
* @hibernate.id
* generator-class=”assigned”
* type=”java.math.BigDecimal”
* column=”ID”
*/
public BigDecimal getId() {
return myId;
}

public void setId(BigDecimal theId) {
myId = theId;
}

/**
* @hibernate.property
* column=”AGE”
*/
public String getAge() {
return myAge;
}

public void setAge(String theAge) {
myAge = theAge;
}
}
—-

The child class:

—-
import java.io.Serializable;

/**
* @hibernate.joined-subclass
* table=”CAT”
*
* @hibernate.joined-subclass-key
* column=”ID”
*/
public class Cat extends Animal implements Serializable {

/** identifier field */
private String myName;

/** default constructor */
public Cat() {
super();
}

/**
* @hibernate.property
* column=”NAME”
*/
public String getName() {
return myName;
}

public void setName(String theName) {
myName = theName;
}
}
—-

… this is generated when running XDoclet:

—-
<?xml version=”1.0″ encoding=”UTF-8″?>

<!DOCTYPE hibernate-mapping PUBLIC
“-//Hibernate/Hibernate Mapping DTD 2.0//EN”
“http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd”>

<hibernate-mapping
>
<class
name=”Animal”
table=”ANIMAL”
dynamic-update=”false”
dynamic-insert=”false”
select-before-update=”false”
optimistic-lock=”version”
>

<id
name=”id”
column=”ID”
type=”java.math.BigDecimal”
>
<generator class=”assigned”>
<!–
To add non XDoclet generator parameters, create a file named
hibernate-generator-params-Animal.xml
containing the additional parameters and place it in your merge dir.
–>
</generator>
</id>

<property
name=”age”
type=”java.lang.String”
update=”true”
insert=”true”
access=”property”
column=”AGE”
/>

<!–
To add non XDoclet property mappings, create a file named
hibernate-properties-Animal.xml
containing the additional properties and place it in your merge dir.
–>

<joined-subclass
name=”com.ipx.hibernate.Cat”
table=”CAT”
dynamic-update=”false”
dynamic-insert=”false”
>
<key
column=”ID”
/>
<property
name=”name”
type=”java.lang.String”
update=”true”
insert=”true”
access=”property”
column=”NAME”
/>

</joined-subclass>

</class>

</hibernate-mapping>

Very annoying as there appears to be no way to override it, but given the fact that all my Hibernate mappings are generated, I’m not too worried about overly complex metadata.

Also, if there are say 3 classes, and the middle class doesn’t need to be persisted, xdoclet cannot proceed to the very last child unless the middle class too is given un-necessary hibernate tags.

It did throw me later that the generated code was inside the parent class’s mapping file. Generally I’m getting more frustrated with XDoclet and I’m ready to get us away from that tool altogether. Most agonizing is the fact that XDoclet breaks if you use ANY of the Java 1.5 language features. I’ve seen indication somewhere that this is fixed as of XDoclet 1.5, but I can’t find a 1.5 anywhere, and it certainly won’t be compatible with JBoss-IDE in Eclipse.

I’m just anxious to move to Hibernate 3 Annotations as quickly as humanly possible!