How to find Entity by Id
fuchs Nov 13, 2009 10:08 AMHello,
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?