The Data Transfer (Domain) object
package com.test.snippets.enterprise;
import java.io.Serializable;
import java.util.Date;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class Employee implements Serializable {
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
private String name;
private String surname;
private String title;
private Double salary;
private Date created;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSurname() {
return surname;
}
public void setSurname(String surname) {
this.surname = surname;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public Double getSalary() {
return salary;
}
public void setSalary(Double salary) {
this.salary = salary;
}
public Date getCreated() {
return created;
}
public void setCreated(Date created) {
this.created = created;
}
@Override
public String toString() {
return "Employee [id=" + id + ", name=" + name + ", surname=" + surname
+ ", title=" + title + ", salary="+salary+ ", created=" + created+"]";
}
}
The EJB implementation class
package com.test.snippets.enterprise;
import java.util.Collection;
import java.util.Date;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.ejb.Remove;
import javax.ejb.Stateful;
import javax.ejb.PrePassivate;
import javax.ejb.PostActivate;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceContextType;
import javax.persistence.Query;
@Stateful
public class EmployeeService implements EmployeeServiceLocal, EmployeeServiceRemote {
/*
* With a Stateful Session Bean a Persistent Context of EXTENDED Type can be used.
* Usually, an EntityManager lives and dies within a JTA transaction. Once the
* transaction is finished, all persistent objects are detached from the EntityManager
* and are no longer managed. Any local caching the EntityManager instance had done is lost.
* In addition you can define long-living EntityManagers that live beyond the scope of a JTA
* transaction. This is called an Extended Persistence Context. When you specify that an
* injected EntityManager is an extended persistence context, all object instances remain
* managed. Extended persistence contexts can only be used within Stateful session beans.
*/
@PersistenceContext(unitName = "TutorialPU", type = PersistenceContextType.EXTENDED)
EntityManager entityManager;
public EmployeeService() {
}
public Employee createEmployee(String name, String surname, String title, double salary) {
Employee employee = new Employee();
employee.setName(name);
employee.setSurname(surname);
employee.setTitle(title);
employee.setSalary(salary);
employee.setCreated(new Date());
entityManager.persist(employee);
return employee;
}
public void removeEmployee(long id) {
Employee employee = findEmployee(id);
if (employee != null) {
entityManager.remove(employee);
}
}
public Employee promoteEmployee(long id, String newTitle, double newSalary) {
Employee employee = entityManager.find(Employee.class, id);
if (employee != null) {
employee.setTitle(newTitle);
employee.setSalary(newSalary);
}
return employee;
}
public Employee findEmployee(long id) {
return entityManager.find(Employee.class, id);
}
public Collection<Employee> findAllEmployees() {
Query query = entityManager.createQuery("SELECT e FROM Employee e");
return (Collection<Employee>) query.getResultList();
}
// Lifecycle operations
@PostConstruct
public void PostConstruct() {
System.out.println("PostConstruct");
}
@PostActivate
public void PostActivate() {
System.out.println("PostActivate");
}
@PrePassivate
public void PrePassivate() {
System.out.println("PrePassivate");
}
@PreDestroy
public void shutdown() {
System.out.println("PreDestroy");
}
@Remove
public void remove() {
System.out.println("Remove");
}
}
The EJB local interface (suitable for in VM communication)
package com.test.snippets.enterprise;
import java.util.Collection;
import javax.ejb.Local;
@Local
public interface EmployeeServiceLocal {
public Employee createEmployee(String name, String surname, String title, double salary);
public void removeEmployee(long id);
public Employee promoteEmployee(long id, String newTitle, double newSalary);
public Employee findEmployee(long id);
public Collection<Employee> findAllEmployees();
}
The EJB remote interface (suitable for intra VM communication)
package com.test.snippets.enterprise;
import java.util.Collection;
import javax.ejb.Remote;
@Remote
public interface EmployeeServiceRemote {
public Employee createEmployee(String name, String surname, String title, double salary);
public void removeEmployee(long id);
public Employee promoteEmployee(long id, String newTitle, double newSalary);
public Employee findEmployee(long id);
public Collection<Employee> findAllEmployees();
}
The persistence.xml file driving the JPA framework
<persistence 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" version="1.0">
<persistence-unit name="TutorialPU" >
<jta-data-source>java:/DefaultDS</jta-data-source>
<properties>
<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
</properties>
<!--
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
<property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
<property name="hibernate.connection.username" value="sa"/>
<property name="hibernate.connection.password" value=""/>
<property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
</properties>
-->
</persistence-unit>
</persistence>
The application.xml file describing the modules in the .ear archive
<?xml version="1.0" encoding="UTF-8"?>
<application xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/application_1_4.xsd"
version="1.4">
<display-name>ExampleEJB3</display-name>
<module>
<java>exampleEJB3-persistence.jar</java>
</module>
<module>
<ejb>exampleEJB3.jar</ejb>
</module>
</application>
The structure of the .ear archive
exampleEJB3.ear
|
|_exampleEJB3-persistence.jar
| |_com
| | |_test
| | |_snippets
| | |_enterprise
| | |_Employee.class
| |_META-INF
| |_persistence.xml
|
|_exampleEJB3.jar
| |_com
| | |_test
| | |_snippets
| | |_enterprise
| | |_EmployeeService.class
| | |_EmployeeServiceLocal.class
| | |_EmployeeServiceRemote.class
| |_META-INF
|
|_META-INF
|_application.xml
An example client
package com.javacodegeeks.snippets.enterprise;
import java.util.Hashtable;
import javax.naming.Context;
import javax.naming.InitialContext;
public class EmployeeServiceClient {
public static void main(String[] a) throws Exception {
/*
* Connecting to JBoss naming service running on local host and on
* default port 1099 the environment that should be created is like the
* one shown below :
*/
Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
env.put(Context.PROVIDER_URL, "jnp://localhost:1099");
env.put(Context.URL_PKG_PREFIXES, "org.jboss.naming:org.jnp.interfaces");
Context ctx = new InitialContext(env);
// We get a reference of the remote EJB interface to invoke its business methods
EmployeeServiceRemote employeeService = (EmployeeServiceRemote) ctx.lookup("exampleEJB3/EmployeeService/remote");
Employee employee = employeeService.createEmployee("Byron", "Kiourtzoglou", "Master Software Engineer", 2000d);
long employeeId = employee.getId();
System.out.println(employeeService.findEmployee(employeeId));
employeeService.promoteEmployee(employeeId, "Principal Software Engineer", 3000d);
System.out.println(employeeService.findEmployee(employeeId));
}
}
Output:
Employee [id=1, name=Byron, surname=Kiourtzoglou, title=Master Software Engineer, salary=2000.0, created=2011-12-03 17:31:30.203]
Employee [id=1, name=Byron, surname=Kiourtzoglou, title=Principal Software Engineer, salary=3000.0, created=2011-12-03 17:31:30.203]
