shoppingcart.java

beginJsp2.0外文书籍源代码

package com.wrox.shop;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;

/**
 * Models a shopping cart holding a number of Books.
 */
public class ShoppingCart extends ActionForm {
    
    private final List items = new ArrayList();
    
    /**
     * Retrieves the items in the cart.
     * @return The cart items.
     */
    public List getItems() {
        return items;
    }
    
    /**
     * Retrieves a specific item.
     * @param index The number in the list.
     * @return The item.
     */    
    public ShoppingCartItem getItem(int index) {
        return (ShoppingCartItem)items.get(index);
    }
    
    /**
     * Sets a specific item.
     * @param index The number in the list.
     * @param item The item.
     */    
    public void setItem(int index, ShoppingCartItem item) {
        items.set(index, item);
    }
    
    /**
     * Retrieves the total cost for the cart.
     * @return The total cost.
     */    
    public double getTotal() {
        double total = 0.0;
        for (Iterator i = items.iterator(); i.hasNext(); ) {
            ShoppingCartItem item = (ShoppingCartItem)i.next();
            total += item.getBook().getPrice() * item.getQuantity();
        }
        return total;
    }
    
    /**
     * Adds a Book to the Cart. If the book is already in the cart, its 
     * quantity is increased by one.
     * @param book The Book to add.
     */    
    public void addBook(Book book) {
        ShoppingCartItem newItem = new ShoppingCartItem(book);
        if (items.contains(newItem)) {
            ShoppingCartItem item = getItem(items.indexOf(newItem));
            item.setQuantity(item.getQuantity() + 1);
        } else {
            items.add(newItem);
        }
    }
    
    /**
     * Validates the book and removes any zero (or negative) quantity
     * books from the cart. Called by the Struts controller.
     * @param mapping The ActionMapping
     * @param request The current request
     * @return <code>null</code> (always valid)
     */    
    public ActionErrors validate(ActionMapping mapping, 
                                 HttpServletRequest request) {
        for (Iterator i = items.iterator(); i.hasNext(); ) {
            ShoppingCartItem item = (ShoppingCartItem)i.next();
            if (item.getQuantity() <= 0) { i.remove(); }
        }
        return null;
    }
}