shoppingcart.java

用jsp编写的一个简单的网上书店系统,数据库用的mysql

package cart;

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


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

    public ShoppingCart() {
        items = new HashMap();
    }
    
    /*
     * 把选购书籍放入购物车
     */
    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());
        }
        
    }
    
    /*
     * 从购物车中删除一本书
     */
    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--;
        }
    }
    /*
     * 购物车所有物品列表
     */
    public synchronized List getItems() {
        List results = new ArrayList();
        Iterator items = this.items.values().iterator();

        while (items.hasNext()) {
            results.add(items.next());
        }

        return (results);
    }

    protected void finalize() throws Throwable {
        items.clear();
    }
    /*
     * 购物车物品数
     */
    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;
    }
    
    /*
     * 购物车物品总价值
     */
    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;
    }
    /*
     * 清空购物车
     */
    public synchronized void clear() {
        System.err.println("Clearing cart.");
        items.clear();
        numberOfItems = 0;
    }
}