Screaming Penguin

I will try to expand on this later, but for now I do not have time and wanted to get something on this subject recorded, so here is an ultra short example of using JPA with JEE5 outside of a container.

I used the Oracle Toplink JPA Implementation - they also have some tutorials there, but like many others they get into too much other crap, building a web app, etc.

1. Setup a database and make sure you can access it with the correct perms over the network (I used MySQL and ConnectorJ).

I also used a simple "user" table for my testing, columns: id, name, fullName, password, email.

2. Setup a project in your IDE, use Java 5 and include the TopLink JPA jar and your JDBC driver as dependencies.

3. Create an entity to use with the example, in this case a User bean.

import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class User implements Serializable {
	@Id
	private int id;
	private String email;
	private String fullname;
	private String password;
	private String name;
	private static final long serialVersionUID = 1L;
	public User() {
		super();
	}
	public int getId() {
		return this.id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getEmail() {
		return this.email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	public String getFullname() {
		return this.fullname;
	}
	public void setFullname(String fullname) {
		this.fullname = fullname;
	}
	public String getPassword() {
		return this.password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	public String getName() {
		return this.name;
	}
	public void setName(String name) {
		this.name = name;
	}
}

4. Borrow the standalone EntityManagerFactory setup code from the JPA tutorial to create JPAResourceBean in your own project.

import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
/**
 * This is an Application Scoped bean that holds the JPA 
 * EntityManagerFactory.  By making this bean Applciation scoped the 
 * EntityManagerFactory resource will be created only once for the application
 * and cached here.
 *
 *@author Gordon Yorke
 */
 public class JPAResourceBean {
    protected EntityManagerFactory emf;
    /*
     * Lazily acquire the EntityManagerFactory and cache it.
     */
     public EntityManagerFactory getEMF (){
        if (emf == null){
            emf = Persistence.createEntityManagerFactory("default", new java.util.HashMap());
        }
        return emf;
    }
}

5. Setup your META-INF/persistence.xml resource with the correct properties for your database.

<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 persistence_1_0.xsd" version="1.0">
  <persistence-unit name="default" transaction-type="RESOURCE_LOCAL">
   <provider>oracle.toplink.essentials.PersistenceProvider</provider>
    <class>com.totsp.datatest.User</class>
    <properties>
     <property name="toplink.logging.level" value="FINEST"/>
     <property name="toplink.jdbc.driver" value="com.mysql.jdbc.Driver"/>
     <property name="toplink.jdbc.url" value="jdbc:mysql://192.168.0.10:3306/totsp"/>
     <property name="toplink.jdbc.user" value="totsp"/>
     <property name="toplink.jdbc.password" value="password"/>
   </properties>
  </persistence-unit>
</persistence></pre>

6. Create a testing class that will persist the entity and run it.

import javax.persistence.EntityManagerFactory;
import oracle.toplink.essentials.ejb.cmp3.EntityManager;
public class Driver
{    
    public static void main(String[] args)
    {
        EntityManagerFactory emf = new JPAResourceBean().getEMF();
        EntityManager entityManager = (EntityManager) emf.createEntityManager();        
        entityManager.getTransaction().begin();
        User user = new User();
        user.setEmail("email");
        user.setFullname("fullname");
        user.setPassword("password");
        user.setName("name");
        entityManager.persist(user);
        entityManager.getTransaction().commit();        
    }    
}

7. Voila! Look at the database, it should have a user in it. (And keep in mind this is supposed to be a super-short learning example, from here you need to read more about JPA in order to learn how to use it in a production environment - this example is not production-worthy.)