How to find Entity by Id

[fuchs]

Hello,
i am using jboss portal 2.7.2 bundle with jboss 4.2.3 and i like to use ejb3 persistence for database query.
But i get this exception:

15:45:31,530 ERROR [CustomerHome] get failed
 java.lang.NullPointerException
 at swk.hibernate.dao.CustomerHome.findById(Unknown Source)
 at de.counter.CounterBean.<init>(CounterBean.java:69)

My datasource:

<datasources>
 <local-tx-datasource>
 <jndi-name>HelloWorldDS</jndi-name>
 <connection-url>jdbc:mysql://xxxx/xxxx</connection-url>
 <driver-class>com.mysql.jdbc.Driver</driver-class>
 <user-name>xxxx</user-name>
 <password>xxxx</password>
 <min-pool-size>5</min-pool-size>
 <max-pool-size>20</max-pool-size>
 </local-tx-datasource>
</datasources>

persistence.xml:

<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
 <persistence-unit name="customerdb">
 <provider>org.hibernate.ejb.HibernatePersistence</provider>
 <jta-data-source>java:/HelloWorldDS</jta-data-source>
 <properties>
 <property name="hibernate.archive.autodetection" value="class, hbm"></property>
 <property name="hibernate.show_sql" value="true"/>
 <property name="hibernate.format_sql" value="true"/>
 <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
 </properties>
 </persistence-unit>
</persistence>

and the entity with Stateless Home Class:

CustomerEntity
@Entity
@Table(name = "Customer", catalog = "swkcustomerportal")
public class Customer implements java.io.Serializable {

 private Integer idCustomer;
 private String jbossUser;
 ...

 public Customer() {
 }

 public Customer(String jbossUser, ...) {
 this.jbossUser = jbossUser;
 ...
 }

 public Customer(String jbossUser, ....)
 ...
 }

 @Id
 @GeneratedValue(strategy = IDENTITY)
 @Column(name = "idCustomer", unique = true, nullable = false)
 public Integer getIdCustomer() {
 return this.idCustomer;
 }

 protected void setIdCustomer(Integer idCustomer) {
 this.idCustomer = idCustomer;
 }
 ...

CustomerHomeStateless
@Stateless
public class CustomerHome {

 private static final Log log = LogFactory.getLog(CustomerHome.class);

 @PersistenceContext(unitName="customerdb")
 private EntityManager entityManager;

 public void persist(Customer transientInstance) {
 ...
 }

 public void remove(Customer persistentInstance) {
 ...
 }

 public Customer merge(Customer detachedInstance) {
 ...
 }

 public Customer findById(Integer id) {
 log.debug("getting Customer instance with id: " + id);
 try {

 Customer instance = (Customer)entityManager.find(Customer.class, id);
 log.debug("get successful");
 return instance;
 } catch (RuntimeException re) {
 log.error("get failed", re);
 throw re;
 }
 }
}

I shorted the Classes to give an easier overview.
The Customer and the CustomerHome are in different packages of the same jar File. I thought that it is no problem.

Jboss Console gives me the following information:

15:28:33,054 INFO [JmxKernelAbstraction] creating wrapper delegate for: org.jboss.ejb3.entity.PersistenceUnitDeployment
 15:28:33,070 INFO [JmxKernelAbstraction] installing MBean: persistence.units:jar=HibernateCustomer.jar,unitName=customerdb with dependencies:
 15:28:33,070 INFO [JmxKernelAbstraction] jboss.jca:name=HelloWorldDS,service=DataSourceBinding
 15:28:33,086 INFO [PersistenceUnitDeployment] Starting persistence unit persistence.units:jar=HibernateCustomer.jar,unitName=customerdb
 15:28:33,164 INFO [Version] Hibernate EntityManager 3.2.1.GA
 15:28:33,164 INFO [Version] Hibernate Annotations 3.2.1.GA
 15:28:33,351 INFO [Ejb3Configuration] found EJB3 Entity bean: swk.hibernate.model.Customer
 ...
 15:28:34,773 INFO [HbmBinder] Mapping class: swk.hibernate.model.Customer -> Customer
 ...
 15:28:36,273 INFO [SessionFactoryObjectFactory] Factory name: persistence.units:jar=HibernateCustomer.jar,unitName=customerdb
 15:28:36,273 INFO [NamingHelper] JNDI InitialContext properties:{java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory, java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces}
 15:28:36,289 INFO [SessionFactoryObjectFactory] Bound factory to JNDI name: persistence.units:jar=HibernateCustomer.jar,unitName=customerdb
 15:28:36,289 WARN [SessionFactoryObjectFactory] InitialContext did not implement EventContext
 15:28:36,289 INFO [NamingHelper] JNDI InitialContext properties:{java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory, java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces}
 15:28:36,742 INFO [JmxKernelAbstraction] creating wrapper delegate for: org.jboss.ejb3.stateless.StatelessContainer
 15:28:37,039 INFO [JmxKernelAbstraction] installing MBean: jboss.j2ee:jar=HibernateCustomer.jar,name=CustomerHome,service=EJB3 with dependencies:
 15:28:37,039 INFO [JmxKernelAbstraction] persistence.units:jar=HibernateCustomer.jar,unitName=customerdb
 15:28:37,055 INFO [EJBContainer] STARTED EJB: swk.hibernate.dao.CustomerHome ejbName: CustomerHome
 15:28:37,055 INFO [JmxKernelAbstraction] creating wrapper delegate for: org.jboss.ejb3.stateless.StatelessContainer
 ...
 15:28:37,289 INFO [EJB3Deployer] Deployed: file:/D:/server/jboss-portal-2.7.2/server/default/deploy/HibernateCustomer.jar

My portlet does the following:

Customer customers;
 ...

 public CounterBean() {
 ...
 try {
 customers = (Customer) new CustomerHome().findById(1);
 ...

I must omit something, or I did not understand it correctly.
Can someone help me?

[jaikiran]

new CustomerHome()

CustomerHome is a @Stateless bean. You are not supposed to instantiate a EJB using the new operator. Instead you should lookup the bean from JNDI. See this for more details http://www.jboss.org/index.html?module=bb&op=viewtopic&t=137590#4158957

[fuchs]

I couldnt find a JNDIView where my CustomerHome is listed, so i took CustomerHome because of the console output where the ejbname is CustomerHome.
Where could i proof the name of the jndi name for my CustomerHome?

I made a lookup in the client.

Context context = new InitialContext();
CustomerHome customer = (CustomerHome)context.lookup("CustomerHome");
customer.findById(1);

And become the Error Message:

ERROR [JBossInjectionProvider] Injection failed on managed bean.
 javax.naming.NameNotFoundException: de.counter.CounterBean not bound
 at org.jnp.server.NamingServer.getBinding(NamingServer.java:529)

So I thought, jbossinjectionprovider doesnt know where the managedbean has to lookup. That way i gave it these properties.

Properties properties = new Properties();
properties.put("java.naming.factory.initial","org.jnp.interfaces.NamingContextFactory");
properties.put("java.naming.factory.url.pkgs","=org.jboss.naming:org.jnp.interfaces");
properties.put("java.naming.provider.url","localhost:1099");

Now, i am getting nothing. no error, no success message.
If i cancel my changes (the properties or give a other jndi name) it is always the same, no answers from the console.
Sorry, but that has completly confused me.

[wolfgangknauf]

Hi,

the JNDIView is here: http://www.jboss.org/community/wiki/DisplayTheJDNITreeWithTheJMXConsole

The default JNDI name of "CustomerHome" is "EarName/JarName/Beanclass" if the the app is deployed as EAR file. If it is a JAR file, it is "JarName/Beanclass".

You don't need JNDI properties if your portal webapp is running in the same JBoss instance as the EJBs.

Hope this helps

Wolfgang

[fuchs]

Thanks Wolfgang Knauf and jaikiran. That helped me much. Know its working fine.