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Stateless session bean callbacks
PostConstruct
- is invoked when the bean is first created, after any dependency injection is done.
PreDestroy
- is invoked when the bean is removed from the pool or destroyed.
Message-driven bean callbacks
PostConstruct
- is invoked when the bean is first created, after any dependency injection is done.
PreDestroy
- is invoked when the bean is removed from the pool or destroyed.
Stateful session bean callbacks
PostConstruct
- is invoked when the bean is first created, after any dependency injection is done.
PreDestroy
- is invoked when the bean is removed from the pool or destroyed.
It will happen before any @Remove
annotated method is invoked.
PostActivate
PrePassivate
Entity bean callbacks
PrePersist
- Is invoked right before the entity is created in the database.
Will cascade to all entities to which this operation is cascaded.
PostPersist
- Is invoked right after the entity is created in the database.
Will cascade to all entities to which this operation is cascaded.
PreRemove
- Is invoked right before the entity is deleted in the database.
Will cascade to all entities to which this operation is cascaded.
PostRemove
- Is invoked right after the entity is deleted in the database.
Will cascade to all entities to which this operation is cascaded.
PreUpdate
- Takes place right before the database is updated.
PostUpdate
- Takes place immediately after the database has been updated.
PostLoad
- Takes place right after data has been loaded
from the database and associated with the entity
The callbacks are not compulsory, and you can define the ones you want to handle.
You use the callbacks listed above by annotating methods in the bean class.
The annotations live in the javax.ejb
package so for example PostConstruct
would be javax.ejb.PostConstruct
. You can call the methods what you like, but their method signature
must return a void and take no arguments. Look at the org.jboss.tutorial.callback.bean.CustomerDAOBean
stateless session bean and you will see that the preDestroyCallback()
method has been annotated with
@javax.ejb.PreDestroy
. For session/message-driven beans, just like for interceptors, if the bean class
extends another class any callback annotated methods on the super class will be invoked first.
You can also separate out the callbacks for entity beans into a separate EntityListener class. Take a look at the
org.jboss.tutorial.callback.bean.Customer
entity bean, and you will see that the class has been annotated with
@javax.persistence.EntityListener("org.jboss.tutorial.callback.bean.CustomerCallbackListener")
.
This specifies that the org.jboss.tutorial.callback.bean.CustomerCallbackListener
class should be used as
the callback listener class for the bean. Now open org.jboss.tutorial.callback.bean.CustomerCalbackListener
and you will see that the class annotates the callback methods in the same way as when defining callbacks on the bean class itself.
However, one __important difference__ is that callback methods defined in a listener class must take a single argument, which will
be the bean we are working with. The parameter must be of type java.lang.Object
, or the actual bean type.
Callbacks for session beans can also be put into a separate class, configured as an interceptor. This means that your interceptors can initialise themselves when constructed. The lifecycle methods in an interceptor must have the following signature:
Object <any method name>(InvocationContext)
org.jboss.tutorial.callback.bean.CustomerDAOBean
specifies that it wants to use an external interceptor.
@Stateless @Remote(CustomerDAO.class) @Interceptors({LifecycleInterceptor.class}) public class CustomerDAOBean implements CustomerDAO { ... }
and org.jboss.tutorial.callback.bean.LifecycleInterceptor
has a @PostConstruct
annotated method.
As shown, each interceptor lifecycle method must call proceed
on the InvocationContext to invoke
the next interceptor. Interceptors may contain both the @AroundInvoke
methods for intercepting
business methods, and lifecycle methods. If you want to configure lifecycle methods for your interceptors with xml,
you will need to do this in the interceptor
section of ejb-jar.xml, and the keywords are
post-construct-method
, post-activate-method
, pre-passivate-method
and pre-destry-method
. For example:
<ejb-jar> <interceptors> <interceptor> <interceptor-class>org.acme.SomeInterceptor</interceptor-class> <around-invoke-method> <method-name>interceptorMethod</method-name> </around-invoke-method> <post-construct-method> <method-name>sendCancelMessage</method-name> </post-construct-method> <pre-destroy-method> <method-name>sendCancelMessage</method-name> </pre-destroy-method> </interceptor> </interceptors> </ejb-jar>
Interceptor methods for handling lifecycle events follow exactly the same ordering and inheritance rules as business method interceptor methods, and an interceptor instance follows the lifecycle of the bean instance it is bound to.
To build and run the example, make sure you have installed JBoss 5.x. See the Section 1.1, “JBoss Application Server 5.x” for details.
From the command prompt, move to the "callbacks" folder under the Section 1.3, “Set the EJB3_TUTORIAL_HOME”
Make sure your JBossAS-5.x is running
$ ant $ ant run run: [java] Create Bill Burke and Monica Smith [java] Bill and Monica get married [java] Get all the Burkes [java] There are now 2 Burkes [java] Bill and Monica are moving abroad
$ mvn clean install -PRunSingleTutorial
In the jboss console window you should see:
23:52:11,162 INFO [STDOUT] LifecycleInterceptor postConstruct 23:52:11,162 INFO [STDOUT] PostConstruct - Have EntityManager: true 23:52:11,424 INFO [STDOUT] -- CustomerDAOBean.create() 23:52:11,575 INFO [STDOUT] doPrePersist: About to create Customer: Bill Burke 23:52:11,608 INFO [STDOUT] doPostPersist: Created Customer: Bill Burke 23:52:11,644 INFO [STDOUT] -- CustomerDAOBean.create() 23:52:11,644 INFO [STDOUT] doPrePersist: About to create Customer: Monica Smith 23:52:11,645 INFO [STDOUT] doPostPersist: Created Customer: Monica Smith 23:52:11,655 INFO [STDOUT] -- CustomerDAOBean.find() 23:52:11,673 INFO [STDOUT] doPostLoad: Loaded Customer: Monica Smith 23:52:11,700 INFO [STDOUT] -- CustomerDAOBean.merge() 23:52:11,704 INFO [STDOUT] doPostLoad: Loaded Customer: Monica Smith 23:52:11,705 INFO [STDOUT] doPreUpdate: About to update Customer: Monica Burke 23:52:11,727 INFO [STDOUT] doPostUpdate: Updated Customer: Monica Burke 23:52:11,735 INFO [STDOUT] -- CustomerDAOBean.findByLastName(id) 23:52:12,101 INFO [STDOUT] doPostLoad: Loaded Customer: Bill Burke 23:52:12,102 INFO [STDOUT] doPostLoad: Loaded Customer: Monica Burke 23:52:12,113 INFO [STDOUT] -- CustomerDAOBean.delete() 23:52:12,116 INFO [STDOUT] doPostLoad: Loaded Customer: Bill Burke 23:52:12,118 INFO [STDOUT] doPreRemove: About to delete Customer: Bill Burke 23:52:12,124 INFO [STDOUT] doPostLoad: Loaded Customer: Monica Burke 23:52:12,125 INFO [STDOUT] doPreRemove: About to delete Customer: Monica Burke 23:52:12,128 INFO [STDOUT] doPostRemove: Deleted Customer: Bill Burke 23:52:12,128 INFO [STDOUT] doPostRemove: Deleted Customer: Monica Burke
Now if you open up the persistence.xml, in this tutorial, and uncomment the following:
<property name="hibernate.show_sql" value="true"/>
and rebuild and run the tutorial, the output should be:
00:00:24,514 INFO [STDOUT] LifecycleInterceptor postConstruct 00:00:24,514 INFO [STDOUT] PostConstruct - Have EntityManager: true 00:00:24,759 INFO [STDOUT] -- CustomerDAOBean.create() 00:00:24,760 INFO [STDOUT] doPrePersist: About to create Customer: Bill Burke 00:00:24,760 INFO [STDOUT] Hibernate: insert into CUSTOMER (id, CITY, FIRST, LAST, STATE, STREET, ZIP) values (null, ?, ?, ?, ?, ?, ?) 00:00:24,761 INFO [STDOUT] Hibernate: call identity() 00:00:24,762 INFO [STDOUT] doPostPersist: Created Customer: Bill Burke 00:00:24,773 INFO [STDOUT] -- CustomerDAOBean.create() 00:00:24,773 INFO [STDOUT] doPrePersist: About to create Customer: Monica Smith 00:00:24,774 INFO [STDOUT] Hibernate: insert into CUSTOMER (id, CITY, FIRST, LAST, STATE, STREET, ZIP) values (null, ?, ?, ?, ?, ?, ?) 00:00:24,774 INFO [STDOUT] Hibernate: call identity() 00:00:24,775 INFO [STDOUT] doPostPersist: Created Customer: Monica Smith 00:00:24,784 INFO [STDOUT] -- CustomerDAOBean.find() 00:00:24,785 INFO [STDOUT] Hibernate: select customer0_.id as id8_0_, customer0_.CITY as CITY8_0_, customer0_.FIRST as FIRST8_0_, customer0_.LAST as LAST8_0_, customer0_.STATE as STATE8_0_, customer0_.STREET as STREET8_0_, customer0_.ZIP as ZIP8_0_ from CUSTOMER customer0_ where customer0_.id=? 00:00:24,786 INFO [STDOUT] doPostLoad: Loaded Customer: Monica Smith 00:00:24,817 INFO [STDOUT] -- CustomerDAOBean.merge() 00:00:24,818 INFO [STDOUT] Hibernate: select customer0_.id as id8_0_, customer0_.CITY as CITY8_0_, customer0_.FIRST as FIRST8_0_, customer0_.LAST as LAST8_0_, customer0_.STATE as STATE8_0_, customer0_.STREET as STREET8_0_, customer0_.ZIP as ZIP8_0_ from CUSTOMER customer0_ where customer0_.id=? 00:00:24,818 INFO [STDOUT] doPostLoad: Loaded Customer: Monica Smith 00:00:24,818 INFO [STDOUT] doPreUpdate: About to update Customer: Monica Burke 00:00:24,820 INFO [STDOUT] Hibernate: update CUSTOMER set CITY=?, FIRST=?, LAST=?, STATE=?, STREET=?, ZIP=? where id=? 00:00:24,820 INFO [STDOUT] doPostUpdate: Updated Customer: Monica Burke 00:00:24,834 INFO [STDOUT] -- CustomerDAOBean.findByLastName(id) 00:00:24,880 INFO [STDOUT] Hibernate: select customer0_.id as id8_, customer0_.CITY as CITY8_, customer0_.FIRST as FIRST8_, customer0_.LAST as LAST8_, customer0_.STATE as STATE8_, customer0_.STREET as STREET8_, customer0_.ZIP as ZIP8_ from CUSTOMER customer0_ where customer0_.LAST=? 00:00:24,881 INFO [STDOUT] doPostLoad: Loaded Customer: Bill Burke 00:00:24,881 INFO [STDOUT] doPostLoad: Loaded Customer: Monica Burke 00:00:24,896 INFO [STDOUT] -- CustomerDAOBean.delete() 00:00:24,897 INFO [STDOUT] Hibernate: select customer0_.id as id8_0_, customer0_.CITY as CITY8_0_, customer0_.FIRST as FIRST8_0_, customer0_.LAST as LAST8_0_, customer0_.STATE as STATE8_0_, customer0_.STREET as STREET8_0_, customer0_.ZIP as ZIP8_0_ from CUSTOMER customer0_ where customer0_.id=? 00:00:24,897 INFO [STDOUT] doPostLoad: Loaded Customer: Bill Burke 00:00:24,898 INFO [STDOUT] doPreRemove: About to delete Customer: Bill Burke 00:00:24,898 INFO [STDOUT] Hibernate: select customer0_.id as id8_0_, customer0_.CITY as CITY8_0_, customer0_.FIRST as FIRST8_0_, customer0_.LAST as LAST8_0_, customer0_.STATE as STATE8_0_, customer0_.STREET as STREET8_0_, customer0_.ZIP as ZIP8_0_ from CUSTOMER customer0_ where customer0_.id=? 00:00:24,899 INFO [STDOUT] doPostLoad: Loaded Customer: Monica Burke 00:00:24,899 INFO [STDOUT] doPreRemove: About to delete Customer: Monica Burke 00:00:24,900 INFO [STDOUT] Hibernate: delete from CUSTOMER where id=? 00:00:24,900 INFO [STDOUT] doPostRemove: Deleted Customer: Bill Burke 00:00:24,900 INFO [STDOUT] Hibernate: delete from CUSTOMER where id=? 00:00:24,900 INFO [STDOUT] doPostRemove: Deleted Customer: Monica Burke
Thus you can see how the callbacks on the entity bean wrap the interaction with the database.