J2EE课程设计的购物车代码（水平有限，仅供参考）

public class CartAction extends ActionSupport{

    private int book_id;
    private int num;
    private String bookname;
    private String author;
    private String publisher;
    private String isbn;
    private float price;
    private String picture;
    private int qty;
    private float total;
    
    
    public int getBook_id() {
        return book_id;
    }

    public void setBook_id(int book_id) {
        this.book_id = book_id;
    }

    public int getNum() {
        return num;
    }

    public void setNum(int num) {
        this.num = num;
    }

    public String getBookname() {
        return bookname;
    }

    public void setBookname(String bookname) {
        this.bookname = bookname;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public String getPublisher() {
        return publisher;
    }

    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }

    public String getIsbn() {
        return isbn;
    }

    public void setIsbn(String isbn) {
        this.isbn = isbn;
    }

    public float getPrice() {
        return price;
    }

    public void setPrice(float price) {
        this.price = price;
    }

    public String getPicture() {
        return picture;
    }

    public void setPicture(String picture) {
        this.picture = picture;
    }
    public int getQty() {
        return qty;
    }
    public void setQty(int qty) {
        this.qty = qty;
    }
    public float getTotal() {
        Map session=ActionContext.getContext().getSession();
        List<Cart> list=(List<Cart>)session.get("cart_list");
        int size=list.size();
        total=0;
        if(size==1){
            total=list.get(0).getPrice()*list.get(0).getNum();
            session.put("total", total);
            return total;
        }
        for(int i=0;i<size;i++){
            total=total+list.get(i).getPrice()*list.get(i).getNum();
        }
        session.put("total", total);
        return total;
    }
    public void setTotal(float total) {
        this.total = total;
    }

    public String add(){
        Map session=ActionContext.getContext().getSession();
        List<Cart> list=(List<Cart>)session.get("cart_list");
        Cart cart = new Cart();
        cart.setBook_id(book_id);
        cart.setNum(num);
        cart.setBookname(bookname);
        System.out.println(bookname);
        cart.setAuthor(author);
        cart.setPublisher(publisher);
        cart.setIsbn(isbn);
        cart.setPrice((float)price);
        cart.setPicture(picture);
        cart.setQty(qty);
        if(list==null){
            System.out.print("null");
            list=new ArrayList<Cart>();
            list.add(cart);
        }
        else if(search(list)!=-1){
            int i=search(list);
            System.out.print("contains");
            Cart cart2 = list.get(i);
            list.remove(i);
            cart2.setNum(cart2.getNum()+num);
            System.out.print(cart2.getNum()+num);
            list.add(cart2);
        }
        else{
            System.out.print("add");
            list.add(cart);
        }
        System.out.println(list.size());
        session.put("cart_list", list);
        this.getTotal();
        return "cart";
        }
    
    public String edit(){
        Map session=ActionContext.getContext().getSession();
        List<Cart> list=(List<Cart>)session.get("cart_list");
        int i=search(list);
        Cart cart2 = list.get(i);
        list.remove(i);
        cart2.setNum(num);
        list.add(cart2);
        session.put("cart_list", list);
        this.getTotal();
        return "cart";
    }

    public String del(){
        Map session=ActionContext.getContext().getSession();
        List<Cart> list=(List<Cart>)session.get("cart_list");
        int i=search(list);
        list.remove(i);
        session.put("cart_list", list);
        this.getTotal();
        return "cart";
    }
    
    
    public int search(List<Cart> list){
        int size=list.size();
        if(size==1){
            if(list.get(0).getBook_id()==book_id){
                return 0;
            }
        }
        for(int i=0;i<size;i++){
            if(list.get(i).getBook_id()==book_id){
                return i;
            }
        }
        return -1;
    }

}

这里是用ArrayList实现的购物车：

getTotal()计算购物车中图书的总价钱；

add()把图书添加进购物车；

edit()修改购物车中图书的数量；

del()删除购物车中的图书；

search(List<Cart> list)是我原创的，用于在购物车中判断特定id的图书是否存在。 

如果需要完整源代码，可以与我联系。