EJB 3.0 Tutorial

The Remote Interface - The first part of creating the BookRemote EJB is to define its remote interface. This interface specifies what business methods a client is allowed to invoke on the EJB. Clients interact with the bookstore's createBook( ) and findBook( ) methods to manipulate Book entities:

import javax.ejb.Remote;

@Remote
public interface BookRemote {

public void createBook(Book book);
public Book findBook(int id);
}

The Bean Class

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

import javax.persistence.PersistenceContext;

@Stateless
public class BookBean implements BookRemote{
@PersistenceContext
(unitName="book")
private EntityManager manager;

public void createBook(Book book) {
manager.persist(book);
}

public Book findBook(int pKey) {
return manager.find(Book.class, pKey);
}
}

The Bean Class

import javax.persistence.*;

@Entity
@Table(name="BOOK")
public class Book implements java.io.Serializable{
private int id;
private String name;
private int price;

@Id
@Column(name="ID")
public int getId( ) { return id; }
public void setId(int pk) { id = pk; }

@Column(name="NAME")
public String getName( ) { return name; }
public void setName(String str) {name = str; }

@Column(name="PRICE")
public int getPrice( ) { return price; }
public void setPrice(int pr) { price = pr; }

}

The persistence.xml File

<persistence>
<persistence-unit name="book">
<jta-data-source>java:/BookDB</jta-data-source>
</persistence-unit>
</persistence