path: root/Master/Reference Architectures and Patterns/EJB 3.0 Code/Gerald Examples/src/examples/shop/impl/session/CartBean.java

package examples.shop.impl.session;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import javax.ejb.Remote;
import javax.ejb.Remove;
import javax.ejb.Stateful;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import examples.shop.impl.entity.Customer;
import examples.shop.impl.entity.LineItem;
import examples.shop.impl.entity.Order;
import examples.shop.impl.entity.Product;
import examples.shop.logic.Cart;

/**
 * This stateful session bean represents a cart which a customer is
 * working on.  A cart is a set of products that the customer is
 * interested in, but has not committed to buying yet.  
 *
 * A cart consists of a series of line items.  Each line item
 * represents one particular product the customer wants, as well as a
 * quantity and discount for that product.
 *
 * The distinction between a cart and an order is that a quote is only
 * temporary and in-memory (hence a stateful session bean), whereas an
 * order is a persistent record (hence an entity).  The cart bean 
 * knows how to transform itself into an order (via the purchase() 
 * method).
 */

@Stateful
@Remote(Cart.class)
public class CartBean implements Cart {

    /**
     * The shopping cart owner
     */
    private String owner;

    /**
     * The shopping cart contents - a vector of LineItems
     */
    private List<LineItem> contents = new ArrayList();

    /**
     * The subtotal (price before taxes) of the goods
     */
    private double subTotal;

    /**
     * The taxes on the goods
     */
    private double taxes;

    @PersistenceContext
    private EntityManager manager;

    public CartBean() {
    }

    /**
     * Get method for the shopping cart owner's name
     * 
     * @return shopping cart owner
     */
    public String getOwner() {
        return owner;
    }

    /**
     * Set method for the shopping cart owner's name
     * 
     * @param shopping
     *            cart owner
     */
    public void setOwner(String owner) {
        this.owner = owner;
    }

    /**
     * Adds an item to the shopping cart
     * 
     * @param shopping
     *            cart lineitem
     */
    public void add(LineItem lineItem) {
        /*
         * Search for an exiting line item in the cart that match 
         * the productID passed in. 
         */
        for (Iterator<LineItem> iter = contents.iterator(); iter.hasNext();) {
            LineItem item = iter.next();
            Product product = item.getProduct();

            if (product != null
                    && product.getProductID().equals(
                            lineItem.getProduct().getProductID())) {
                // found one, modify that line item's quantity and return
                item.setQuantity(item.getQuantity() + lineItem.getQuantity());
                return;
            }
        }

        /*
         * Did not find a match, so add the line item as new.
         */
        contents.add(lineItem);
    }

    /**
     * Changes the quantities of contents in the shopping cart
     * 
     * @param product
     *            Id
     * @param number
     *            of items.
     */
    public void modify(String productID, int quantity) throws Exception {
        System.out.println("CartBean.modify()");

        /*
         * Search for a lineitem in the cart that match the productID passed in.
         * If found, modify that lineitem.
         */
        for (Iterator<LineItem> iter = contents.iterator(); iter.hasNext();) {
            LineItem item = iter.next();
            Product product = item.getProduct();
            if (product != null && product.getProductID().equals(productID)) {
                item.setQuantity(quantity);
                if (quantity == 0) {
                    iter.remove();
                }
                return;
            }
        }
        throw new Exception("CartBean.modify() error: Could not find product "
                + productID);
    }

    /**
     * Returns all the shopping cart line items
     * 
     * @return A collection of Cart LineItems
     */
    public List<LineItem> getAll() {
        return contents;
    }

    /**
     * @return  the subtotal price which has been previously set by
     * setSubtotal().
     */
    public double getSubtotal() {
        return subTotal;
    }

    /**
     * Sets the subtotal price.
     * @param subTotal the subtotal price
     */
    public void setSubtotal(double subTotal) {
        this.subTotal = subTotal;
    }

    /**
     * @return the taxes computed for this Cart.
     */
    public double getTaxes() {
        return taxes;
    }

    /**
     * Sets the taxes for this Cart.
     */
    public void setTaxes(double taxes) {
        System.out.println("CartBean.setTaxes(): " + taxes);
        this.taxes = taxes;
    }

    /**
     * Get the total price. The total Price is computed from:
     * <ol> 
     * <li>Subtotal price
     * <li>Tax
     * </ol>
     * @return the total price. 
     */
    public double getTotalPrice() {
        return subTotal + taxes;
    }

    /**
     * Empties the shopping cart
     */
    public void clear() {
        contents.clear();
    }

    /**
     * Purchases this cart. The cart will create an order in the database 
     * and return the order ID as a confirmation number.
     * 
     * @return The Order confirmation number
     */
    public String purchase() {
        System.out.println("CartBean.purchase()");
        Customer customer = manager.find(Customer.class, owner);

        /*
         * Create the order entity
         */
        Order order = new Order();
        String orderID = makeUniqueID();
        order.init(orderID, customer, Order.Status.Unverified, subTotal, taxes);
        order.setLineItems(prepareContents());
        manager.persist(order);

        /*
         * Sends the JMS message to the topic
         */
        try {
            sendMessage(orderID);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        /*
         * Return the order ID
         */
        return orderID;
    }

    /**
     * Sends a JMS message to a destination (Queue or Topic)
     * 
     * @param a
     *            message string, in this case orderId
     */
    private void sendMessage(String text) throws Exception {
        Connection connection = null;
        MessageProducer producer = null;
        Session session = null;

        try {
            Context jndiContext = new InitialContext();
            ConnectionFactory connectionFactory = (ConnectionFactory) jndiContext
                    .lookup("jms/QueueConnectionFactory");
            Destination destination = (Destination) jndiContext
                    .lookup("jms/OrderQueue");
            connection = connectionFactory.createConnection();
            session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
            producer = session.createProducer(destination);

            connection.start();
            TextMessage msg = session.createTextMessage();
            msg.setText(text);
            producer.send(msg);
        } catch (Exception ex) {
            throw ex;
        } finally {
            if (connection != null) {
                try {
                    producer.close();
                    connection.close();
                    session.close();
                } catch (JMSException e) {
                    // ignore
                }
            }
        }
    }

    /**
     * Generates primary keys for line items and loads the products 
     * into the persistence context.
     */

    private List<LineItem> prepareContents() {
        for (Iterator<LineItem> iter = contents.iterator(); iter.hasNext();) {
            LineItem lineItem = iter.next();
            Product p = manager.find(Product.class, lineItem.getProduct()
                    .getProductID());
            lineItem.setProduct(p);
            lineItem.setId(makeUniqueID());
        }
        return contents;
    }

    /**
     * Returns a unique Id based on current time. Can be removed
     * when AUTO key generation works in Glassfish      * 
     */
    private String makeUniqueID() {
        String id = new Long(System.nanoTime()).toString();
        System.out.println("makeUniqueID: " + id);
        return id;
    }

    /**
     * Removes this quote, and hence all client-
     * specific state.
     */
    @Remove
    public void remove() {
    }
}