8a. Simple shopping cart application using EJB [Stateful Session Bean].

Create EJB File

CartBeanLocal.java

package cart;

import java.util.List;

import javax.ejb.Local;

@Local

public interface CartBeanLocal {

public void initialize(String person) throws Exception;

public void initialize(String person, String id)

throws Exception;

public void addBook(String title);

public void removeBook(String title) throws Exception; public List<String> getContents(); public void remove();

}

CartBean.java ~~~~~~~~~~~~

package cart;

import java.util.ArrayList;

import java.util.List;

import javax.ejb.Remove;

import javax.ejb.Stateful;

@Stateful

public class CartBean implements CartBeanLocal

{

String customerName;

String customerId;

List<String> contents;

public void initialize(String person, String id)

throws Exception {

if (person == null) {

throw new Exception("Null person not allowed."); 

} 

else {

customerName = person;

}

if ( person=="ABC" && id=="123") {

customerId = id;

} 

else {

throw new Exception("Invalid id: " + id);

}

contents = new ArrayList<String>();

}

public void addBook(String title) {

contents.add(title);

}

public void removeBook(String title) throws Exception 

{ 

boolean result = contents.remove(title);

if (result == false) 

{

throw new Exception(title + " not in cart.");

}

}

public List<String> getContents() {

return contents;

}

@Remove

public void remove() {

contents = null;

}

}

CartTestServlet.java

package testcart;

import cart.CartBeanLocal;

import java.io.*;

import java.util.*;

import java.util.logging.Level;

import java.util.logging.Logger;

import javax.naming.*;

import javax.servlet.*;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.*;

@WebServlet(name = "CartTestServlet", urlPatterns = {"/CartTestServlet"})

public class CartTestServlet extends HttpServlet {

CartBeanLocal cartBean = lookupCartBeanLocal();

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException 

{

response.setContentType("text/html;charset=UTF-8");

try{

cartBean.initialize("ABC", "123");

}

catch(Exception e){}

cartBean.addBook("Java 8 Cookbook");

cartBean.addBook("Enterprise Java 7 ");

cartBean.addBook("Java for Dummies");

cartBean.addBook("Learn Java 8");

try (PrintWriter out = response.getWriter()) {

try{

List<String> books = cartBean.getContents();

for( String s : books)

out.println(s +"<br />");

}catch(Exception e){}

}

}

private CartBeanLocal lookupCartBeanLocal() {

try {

Context c = new InitialContext();

return (CartBeanLocal) c.lookup("java:global/EnterpriseApplication1/EnterpriseApplication1-ejb/CartBean!cart.CartBeanLocal");

} catch (NamingException ne) {

Logger.getLogger(getClass().getName()).log(Level.SEVERE, "exception caught", ne);

throw new RuntimeException(ne);

}

}

}