Red Hat Application Server, Руководство пользователя

Страница: 92 / 296

84 Chapter 8. Developing Entity Beans
return null;
}
If nothing else is specified and the JOnAS default CMP 2 database mapping is used, the JOnAS
container generates a database column with the name
JPK_
to handle this PK. However, it is possible
to specify in the JOnAS-specific Deployment Descriptor the name of the column that will be used
to store the PK value in the table. You can do this as follows using the specific
(
automatic-pk-field-
name
)
element (this technique is necessary for CMP2 legacy and for CMP1):
JOnAS-specific deployment descriptor:
*
jonas-ejb-jar xmlns="http://www.objectweb.org/jonas/ns"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.objectweb.org/jonas/ns
http://www.objectweb.org/jonas/ns/jonas-ejb-jar_4_0.xsd"
+
*
jonas-entity
+
*
ejb-name
+
AddressEJB
*
/ejb-name
+
*
jdbc-mapping
+
*
jndi-name
+
jdbc_1
*
/jndi-name
+
*
automatic-pk-field-name
+
FieldPkAuto
*
/automatic-pk-field-name
+
*
/jdbc-mapping
+
*
/jonas-entity
+
8.4.1.1.2. Method 2: CMP Field as Automatic Primary Key (from JOnAS 3.3.x)
The idea here is to declare a typical PK CMP field of type
java.lang.Integer
as
automatic
.
By doing this, the field will no longer appear in
create
methods and its value will be automatically
generated by the container at the EJB instance-creation time. However, it is still a cmp field, with
getter/setter methods, and is accessible from the application.
8.4.1.1.2.1. Method 2 Example:
In the standard deployment descriptor, there is a typical primary key definition:
*
entity
+
...
*
prim-key-class
+
java.lang.Integer
*
/prim-key-class
+
*
cmp-field
+
*
field-name
+
id
*
/field-name
+
*
/cmp-field
+
*
primkey-field
+
id
*
/primkey-field
+
In the JOnAS-specific deployment descriptor, specify that this PK is automatic:
*
jonas-entity
+
...
*
jdbc-mapping
+
*
automatic-pk
+
true
*
/automatic-pk
+