Develop simple shopping cart application using EJB [Stateful Session Bean].

 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; 

    } 

} 

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/EnterpriseApplication1ejb/CartBean!cart.CartBeanLocal");         } catch (NamingException ne) { 

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

        } 

    } 

 

} 

Output :-