shoppingcart.java

《j2ee经典实例详解》的源代码。原书无附带光盘。介绍的是一个在线银行系统的例子。绝对难得

/*
 * Copyright (c) 2005 Sun Microsystems, Inc.  All rights reserved.  U.S.
 * Government Rights - Commercial software.  Government users are subject
 * to the Sun Microsystems, Inc. standard license agreement and
 * applicable provisions of the FAR and its supplements.  Use is subject
 * to license terms.
 *
 * This distribution may include materials developed by third parties.
 * Sun, Sun Microsystems, the Sun logo, Java and J2EE are trademarks
 * or registered trademarks of Sun Microsystems, Inc. in the U.S. and
 * other countries.
 *
 * Copyright (c) 2005 Sun Microsystems, Inc. Tous droits reserves.
 *
 * Droits du gouvernement americain, utilisateurs gouvernementaux - logiciel
 * commercial. Les utilisateurs gouvernementaux sont soumis au contrat de
 * licence standard de Sun Microsystems, Inc., ainsi qu'aux dispositions
 * en vigueur de la FAR (Federal Acquisition Regulations) et des
 * supplements a celles-ci.  Distribue par des licences qui en
 * restreignent l'utilisation.
 *
 * Cette distribution peut comprendre des composants developpes par des
 * tierces parties. Sun, Sun Microsystems, le logo Sun, Java et J2EE
 * sont des marques de fabrique ou des marques deposees de Sun
 * Microsystems, Inc. aux Etats-Unis et dans d'autres pays.
 */


package cart;

import java.util.*;
import database.BookDetails;


public class ShoppingCart {
    HashMap items = null;
    int numberOfItems = 0;

    public ShoppingCart() {
        items = new HashMap();
    }

    public synchronized void add(String bookId, BookDetails book) {
        if (items.containsKey(bookId)) {
            ShoppingCartItem scitem = (ShoppingCartItem) items.get(bookId);
            scitem.incrementQuantity();
            System.out.println("in add, quantity is " + scitem.getQuantity());
        } else {
            ShoppingCartItem newItem = new ShoppingCartItem(book);
            items.put(bookId, newItem);
            System.out.println("in add, quantity is " + newItem.getQuantity());
        }

        //      numberOfItems++;
    }

    public synchronized void remove(String bookId) {
        if (items.containsKey(bookId)) {
            ShoppingCartItem scitem = (ShoppingCartItem) items.get(bookId);
            scitem.decrementQuantity();

            if (scitem.getQuantity() <= 0) {
                items.remove(bookId);
            }

            numberOfItems--;
        }
    }

    public synchronized List getItems() {
        List results = new ArrayList();
        results.addAll(this.items.values());

        return results;
    }

    protected void finalize() throws Throwable {
        items.clear();
    }

    public synchronized int getNumberOfItems() {
        numberOfItems = 0;

        for (Iterator i = getItems()
                              .iterator(); i.hasNext();) {
            ShoppingCartItem item = (ShoppingCartItem) i.next();
            numberOfItems += item.getQuantity();
            System.out.println("number of items is " + numberOfItems);
        }

        return numberOfItems;
    }

    public synchronized double getTotal() {
        double amount = 0.0;

        for (Iterator i = getItems()
                              .iterator(); i.hasNext();) {
            ShoppingCartItem item = (ShoppingCartItem) i.next();
            BookDetails bookDetails = (BookDetails) item.getItem();

            amount += (item.getQuantity() * bookDetails.getPrice());
        }

        return roundOff(amount);
    }

    private double roundOff(double x) {
        long val = Math.round(x * 100); // cents

        return val / 100.0;
    }

    public synchronized void clear() {
        System.err.println("Clearing cart.");
        items.clear();
        numberOfItems = 0;
    }
}