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EJB 3.0 Stateful Session Bean Example

This article demonstrates how to write a simple Stateful Session Bean. It consists of three POJO's: Remote interface Cart.java, Bean class CartBean.java and EJB client CartClient.java.

Prerequisites

In order to complete the example application, you should be familiar with the following:

* EJB 3.0

This demonstration requires that the following software components are installed and configured correctly:

* Application Server such as J2EE, or other
* Sun JDK version 1.5 or above

Remote Interface: Cart.java

Code: Java

package ejb_stateful;

import java.util.Collection;
import javax.ejb.Remote;

@Remote
public interface Cart {
    public void addItem(String item);
    public void removeItem(String item);
    public Collection getItems();
}

Stateful Session Bean: CartBean.java

Code: Java

package ejb_stateful;

import java.util.ArrayList;
import java.util.Collection;
import javax.annotation.PostConstruct;
import javax.ejb.Stateful;

@Stateful
public class CartBean implements Cart {
    private ArrayList items;

    @PostConstruct
    public void initialize() {
        items = new ArrayList();
    }
    
    public void addItem(String item) {
        items.add(item);
    }

    public void removeItem(String item) {
        items.remove(item);
    }

    public Collection getItems() {
        return items;
    }
}

EJB Client: CartClient.java

Code: Java

package ejb_stateful;

import java.util.Collection;
import java.util.Iterator;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;

public class CartClient {
    public static void main(String [] args) throws NamingException {
       
        try {
            final Context context = getInitialContext();
            Cart cart = (Cart)context.lookup("CartBean");
            
            System.out.println("Adding items to cart");
            
            cart.addItem("Pizza");
            cart.addItem("Pasta");
            cart.addItem("Noodles");
            cart.addItem("Bread");
            cart.addItem("Butter");
            
            
            System.out.println("Listing cart contents");
            Collection items = cart.getItems();
            for (Iterator i = items.iterator(); i.hasNext();) {
            String item = (String) i.next();
            System.out.println("  " + item);
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    private static Context getInitialContext() throws NamingException {
        return new InitialContext();
    }
}

Compile all the programs, start the server and execute CartClient. You will see following Output:

Code:

Adding items to cart

Listing cart contents

  Pizza

  Pasta

  Noodles

  Bread

  Butter