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Building the EJB tier

Now it's time to create our EJBs that will the facade to our Model.

Java EE 6 simplifies the application packaging by removing the restriction that enterprise bean classes must be packaged in an ejb-jar file. You can now place EJB classes directly in the .war file, using the same packaging guidelines that apply to web application classes.

As you can see from the above picture, the EJB used in this Web application are packed just as POJO in the Web application classes.

package ejb;

import java.util.List;

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

import model.Customer;
import model.Item;

@Stateless
public class StoreManagerDao {
 @PersistenceContext(unitName = "AppStore")
 private EntityManager em;

 public void createCustomer(String country, String name) {
   Customer customer = new Customer();
   customer.setCountry(country);
   customer.setName(name);
   em.persist(customer);
 }

 public void saveItem(int customerId, int price, int quantity, String product) {
   Customer customer = findCustomerById(customerId);
   Item order = new Item();
   order.setCustomerFK(customer);
   order.setPrice(price);
   order.setQuantity(quantity);
   order.setProduct(product);
   em.persist(order);
 }

 public List<Item> findAllItems(int customerId) {
   Query query = em.createQuery("FROM Customer where id=:id");
   query.setParameter("id", customerId);
   Customer customer = (Customer) query.getSingleResult();

   List<Item> customerOrders = customer.getItems();
   return customerOrders;
 }

 public Customer findCustomerByName(String customerName) {
   Query query = em.createQuery("FROM Customer where name=:name");
   query.setParameter("name", customerName);
   Customer customer = (Customer) query.getSingleResult();
   return customer;
 }

 public Customer findCustomerById(int id) {
   Query query = em.createQuery("FROM Customer where id=:id");
   query.setParameter("id", id);
   Customer customer = (Customer) query.getSingleResult();
   return customer;
 }

 public List<Customer> findAllCustomers() {
   Query query = em.createQuery("FROM Customer");
   List<Customer> customerList = query.getResultList();
   return customerList;
 }
}

This examples uses EJB 3.1 no-interface view. No interfaces EJB simplify the creation of your EJBs by making local business interfaces optional.