将对象从JSP设置为servlet

Question

I've found different solutions, even on stackOverflow, but they don't work for me.

I have a JSP file that dinamically shows product , a Java user-defined object, that has an unique ID. For every product, it should show all infos and a button that says "Add to cart". How can I implement the Add to cart?

My code (JSP):

<% List<Product> queryResults = (ArrayList<Product>) request.getAttribute("queryResults");

        for(Product product : queryResults) { %>

        <table class = "qrtable">

            .......

                <% User currentUser = (User) session.getAttribute("currentSessionUser");
                if (currentUser != null){%> <!-- user is logged -->
                <tr><td  colspan="2">  
                    <form action="${pageContext.request.contextPath}/cart" method="post">
                        <input type="submit" value="Add to cart"/>
                    </form>
                </td></tr>
                 <%} 
            else{

                } %>

            </table>
        <% } %>

How do I add the product to the user cart? How do I pass to the servlet the productID when the "Add to cart" button is pressed?

Answer 1

I've found the solution.

In JSP:

<% User currentUser = (User) session.getAttribute("currentSessionUser");
                if (currentUser != null){%>
                <tr>
                    <td colspan="2">  
                        <form action="${pageContext.request.contextPath}/cart" method="POST">
                            <input type="hidden" name="productID" value="<%=product.getID()%>" />
                            <input type="submit" value="Add to cart"/>
                        </form>
                    </td>
                </tr>
                 <%} else{%>
                <tr>
                    <td colspan="2">Account required to buy.</td>
                </tr>
            <%} %>

In the servlet (method POST ):

int productID = Integer.parseInt(request.getParameter("productID"));

HttpSession session = request.getSession(true);
User loggedUser = (User) session.getAttribute("currentSessionUser");
loggedUser.getShoppingCart().addToCart(ProductDAO.getFromDatabase(productID));