Create stateless session bean accessing database with JPA in Websphere 7

Create a Java project, named ‘ejb3-jpa’

Add runtime Websphere application server 7 to the build path

Under src, create a folder META-INF, under META-INF create persistence.xml

The contents of persistence.xml

<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="unit">
        <jta-data-source>jdbc/derby</jta-data-source>
        <properties>
            <property name="openjpa.Log" value="SQL=TRACE"/>
            <property name="openjpa.jdbc.SynchronizeMappings"     
                  value="buildSchema"/>
            <property name="openjpa.jdbc.MappingDefaults" 
                  value="ForeignKeyDeleteAction=restrict, 
                     JoinForeignKeyDeleteAction=restrict"/>
        </properties>
    </persistence-unit>
</persistence>

jdbc/derby is the JNDI name for the datasource. It should be configured in Websphere application server already.

Openjpa.Log prints out the SQL. (Not working properly in WAS 7)

Openjpa.jdbc.synchronizeMappings creates the tables in the database if they don’t already exist.

openjpa.jdbc.MappingDefaults creates the foreign key constraints.

Create an entity bean: Person.java

 

package entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;


@Entity
@Table(name="T_PERSON")
public class Person{
    
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
    
    @Column(name = "NAME")
    private String name;
    
    public Person() {
        super();
    }
    
    public Person(String name) {
        super();
        this.name = name;
    }
    
    public Person(int id, String name) {
        super();
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

Create a stateless session bean and its local interface: PersonManager.java and PersonManagerBean.java

package session;

import entity.Person;

public interface PersonManager {
    public void save(Person person);
}

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import entity.Person;

@Stateless
@Local(PersonManager.class)
public class PersonManagerBean 
    implements PersonManager {

    @PersistenceContext(unitName="unit")
    private EntityManager em;
    
    @Override
    public void save(Person person) {
        em.persist(person);
    }
}

Create a dynamic web project, named ‘ejb3-jpa-web’

Select ‘Websphere Application Server 7’ as the Target Runtime.

Include ‘ejb3-jpa’ project into the build path

Create a servlet: PersonServlet.java

package web;

import java.io.IOException;

import javax.ejb.EJB;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import session.PersonManager;
import entity.Person;

public class PersonServlet extends HttpServlet {
    
    @EJB
    private PersonManager personManager;

    @Override
    protected void doGet(HttpServletRequest req, 
            HttpServletResponse resp)
            throws ServletException, IOException {
        personManager.save(new Person("Sun"));
    }
}

Define the servlet in web.xml

<servlet>
    <servlet-name>person</servlet-name>
    <servlet-class>web.PersonServlet</servlet-class>
</servlet>
    
<servlet-mapping>
    <servlet-name>person</servlet-name>
    <url-pattern>*.do</url-pattern>
</servlet-mapping>

Create an enterprise project, named ‘ejb3-ear’

Add ‘ejb3-jpa’ and ‘ejb3-jpa-web’ project into ‘ejb3-ear’

Add the ‘ejb3-ear’ project into the server, start the server

Right click on ‘WebSphere Application Server V7.0’, and click on ‘Properties’

 

Find out the port number

Go to http://localhost:PORT_NUMBER/ejb3-jpa-web/a.do

Replace PORT_NUMBER with the actual port number (i.e. 9084)

Check the database