showquoteservlet.java

MasteringEJB20 Code Sample Include SessionBean,EntityBean,etc

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 JNDI initialization parameters.
			 * We externalize these settings to the
			 * servlet properties file to allow end-users
			 * to dynamically reconfigure their
			 * environment without recompilation.
			 */
			String initCtxFactory = getInitParameter(Context.INITIAL_CONTEXT_FACTORY);
			String providerURL = getInitParameter(Context.PROVIDER_URL);

			/*
			 * Add the JNDI init parameters to a
			 * properties object.
			 */
			Properties env = new Properties();
			env.put(Context.INITIAL_CONTEXT_FACTORY, initCtxFactory);
			env.put(Context.PROVIDER_URL, providerURL);

			/*
			 * Get the initial context using the above
			 * startup params.
			 */
			Context ctx = new InitialContext(env);

			/*
			 * Look up the Pricer Home Object.
			 */
			PricerHome pricerHome = (PricerHome) ctx.lookup("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")) {
			}

			/*
			 * If the user wants to clear the form
			 */
			else if (paramName.equals("Clear")) {
				cart.clear();
				this.getServletContext().getRequestDispatcher("/clearQuote.jsp").forward(request, response);
				return;
			}

			/*
			 * 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.
			 */
			else {
                /*
                * Convert the quantity to int format, and set the new quantity
                */
                try {
                    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;
        }
		/*
		 * If there are no products, print out that the
		 * cart is empty.
		 */
		else {
			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.";
	}
}