showquoteservlet.java

EJB实践的服务器是用SUN的服务器

package examples;

import java.io.*;
import java.util.*;
import java.text.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.naming.*;

/**
 * This servlet allows the user to view and modify his
 * current selections.
 *
 * By the time this servlet is called, the user has
 * logged in (via the Login servlet), and has a shopping
 * cart started (i.e. cart bean).  Since this servlet is
 * pooled and re-used for different user requests, the
 * servlet code does not store any information specific
 * to any user.  Rather, we store a reference to the user's
 * cart in the user's HttpSession object, which is globally
 * accessible to all servlets.
 */
public class ShowQuoteServlet 
    extends HttpServlet 
{

    // Pricer EJB Object for pricing the cart
    private Pricer pricer;

    /**
     * The servlet engine calls this method once to initialize
     * a servlet instance.
     *
     * In the body of this method, we need to acquire a Pricer
     * EJB Object for pricing the carts.
     */
    public void init(ServletConfig config) 
        throws ServletException 
    {
        /*
         * Call parent to store the config object, so that
         * getServletConfig() can return it.
         */
        super.init(config);

        try 
        {
            /*
             * Get the initial context using the above
             * startup params.
             */
            Context ctx = new InitialContext();
                    
            /*
             * Look up the Pricer Home Object.
             */
            PricerHome pricerHome = (PricerHome)ctx.lookup("ejb/PricerHome");

            /*
             * Create a Pricer EJB Object.
             */
            pricer = pricerHome.create();
        } 
        catch (Exception e) 
        {
            log(e);
            throw new ServletException(e.toString());
        }
    }

    /**
     * The servlet engine calls this method when the user's
     * desktop browser sends an HTTP GET request.
     */
    public void service (HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException 
    {
        /*
         * Get the user's HttpSession, and from that get the user's
         * current cart.
         */
        HttpSession session = request.getSession(false);
        if (session == null) 
        {
            /*
             * Redirect user to login page if no session
             */
            response.sendRedirect(response.encodeRedirectURL("/jasmine/login"));
            return;
        }

        Object obj = session.getAttribute("cart");
        if (obj == null) 
        {
            /*
             * Redirect user to login page if no session
             */
            response.sendRedirect(response.encodeRedirectURL("/jasmine/login"));
            return;
        }

        Cart cart = (Cart)obj;

        /*
         * If the user clicked the 'Order' button, he wants to
         * purchase his selections.  We forward the user to the
         * servlet that handles purchasing.
         */
        if (request.getParameter("Order") != null) 
        {
            /*
             * First, turn the cart into an order
             */
            String orderId = cart.purchase();
            /*
             * Stick the orderID in the request so the JSP gets it
             */
            request.setAttribute("orderID", orderId );
            cart.clear();
            this.getServletContext().getRequestDispatcher("/receipt.jsp").forward(request, response);
            return;
        }

        /*
         * Next, we need to figure out what button the user clicked,
         * if any.  These come to us as form parameters.  We need to
         * loop through each parameter and interpret it.
         */
        Enumeration paramNames = request.getParameterNames();
        while (paramNames.hasMoreElements()) 
        {
            String paramName = (String) paramNames.nextElement();
            String paramValue = request.getParameter(paramName);

            /*
             * If user clicked 'Update' button, then the user wants to
             * change the quantities of each product he is ordering.
             * We'll process those quantities below.
             */
            if (paramName.equals("Update")) 
            {
            }
            else if (paramName.equals("Clear")) 
            {
                /*
                 * The user wants to clear the form
                 */
                cart.clear();
                this.getServletContext().getRequestDispatcher("/clearQuote.jsp").forward(request, response);
                return;
            }
            else 
            {
                /*
                 * If the parameter represents a quantity of a
                 * particular product the user is interested in, then
                 * we should update that product's quantity to reflect
                 * this new value.
                 */
                try 
                {
                    /*
                     * Convert the quantity to int format, and set the
                     * new quantity
                     */
                    int quantity = Integer.parseInt(paramValue);
                    cart.modify(paramName, quantity);
                } 
                catch (NumberFormatException e) 
                {
                    throw new ServletException("Bad parameter to servlet: " + paramName + ", " + paramValue);
                } 
                catch (Exception e) 
                {
                    throw new ServletException(e.toString());
                }
            }
        }

        /*
         * Recalculate all totals based upon new quantities
         */
        try 
        {
            pricer.price(cart);
        } 
        catch (Exception e) 
        {
            log(e);
            throw new ServletException(e.toString());
        }

        /*
         * Otherwise, show the current cart again
         */
        Vector lineItems = cart.getAll();		
        if (lineItems.size() > 0) 
        {
            /*
             * Stick lineitems, subtotal, taxes and total in request
             */
            request.setAttribute("lineItems", lineItems);
            request.setAttribute("subTotal", new Double(cart.getSubtotal()));
            request.setAttribute("taxes", new Double(cart.getTaxes()));
            request.setAttribute("total", new Double(cart.getTotalPrice()));
            //Forwards the request to the showQuote JSP.
            this.getServletContext().getRequestDispatcher("/showQuote.jsp").forward(request, response);
            return;
        }
        else 
        {
            /*
             * If there are no products, print out that the cart is
             * empty.
             */
            this.getServletContext().getRequestDispatcher("/emptyQuote.jsp").forward(request, response);
            return;
        }
    }

    /**
     * Currency localization formatting
     */
    private String format(double d) 
    {
        NumberFormat nf = NumberFormat.getCurrencyInstance();
        return nf.format(d);
    }

    private void log(Exception e) 
    {
        e.printStackTrace();
    }

    public String getServletInfo() 
    {
        return "The ShowQuote servlet returns information about" +
            "the products that the user is in the process of ordering.";
    }
}