catalogservlet.java

MasteringEJB20 Code Sample Include SessionBean,EntityBean,etc

package examples;

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

/**
 * This servlet displays a catalog of products to
 * the end-user.
 *
 * 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 CatalogServlet extends HttpServlet {

	private CatalogHome catalogHome = null;

	/**
	 * The servlet engine calls this method once to
	 * initialize a servlet instance.
	 *
	 * In the body of this method, we need to acquire the
	 * EJB Catalog Home Object.
	 */
	public void init(ServletConfig config) throws ServletException {

		super.init(config);

		try {
			/*
			 * Get the deployed properties from the
			 * config object.  We externalize the JNDI
			 * initialization params 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 JNDI context using the
			 * above startup params.
			 */
			Context ctx = new InitialContext(env);

			/*
			 * Look up the Catalog Home Object.
			 */
			catalogHome = (CatalogHome ) ctx.lookup("CatalogHome");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * The servlet engine calls this method when the user's
	 * desktop browser sends an HTTP request.
	 */
	public void service (HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {
        Vector	products=null;
		try {

			/*
			 * 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 he
				 * doesn't have a session.
				 */
				response.sendRedirect(response.encodeRedirectURL("/jasmine/login"));
				return;
			}

			Object obj = session.getAttribute("cart");
			if (obj == null) {
				/*
				 * Redirect user to login page if he
				 * doesn't have a session.
				 */
				response.sendRedirect(response.encodeRedirectURL("/jasmine/login"));
				return;
			}
			Cart cart = (Cart) obj;
			String productIDToAdd = request.getParameter("Buy");
			products=(Vector)session.getAttribute("products");
			String productId=(String)request.getParameter("productId");  			

			/*
			 * If user wants to purchase something (via
			 * the URL parameter 'Buy'), add the desired
			 * product item to the cart.
			 */
			
			if (productIDToAdd != null) {
                
            /*
             * Creates LineItem, and add to the cart.
             */
			try {
                ProductItem item=getProductItem(products,productIDToAdd);
                cart.add(new LineItem(item,1,0));
                // Set a flag so that JSP knows which product we purchased
                request.setAttribute("ProductPurchased", item.getName());
                // Forwards the request to the catalog JSP
                this.getServletContext().getRequestDispatcher("/catalog.jsp").forward(request, response);
                return;
			} catch (Exception e) {
                throw new ServletException(e.toString());
            }                                
			}
            /*
			 * If user wants to view the product details (via
			 * the URL parameter 'productId')
			 */
            else if(productId!=null){
                //Retrieves the product item from the prducts vector and pass it in request object.
                request.setAttribute("productItem",getProductItem(products,productId));
                // Forwards the request to the productInfo JSP
                this.getServletContext().getRequestDispatcher("/productInfo.jsp").forward(request, response);
                return;
    		}
            /*
             * If products vector = null,Retrieves productItems vector from Catalog stateless session bean 
             * and put it in the HttpSession. we may need to put this vector in application level instead of session.
             */
            else {
                if(products==null){
                    Catalog catalog=catalogHome.create();
                  	products=catalog.getProductItemList();
                  	session.setAttribute("products", products);
                }	
                // Forwards the request to the catalog JSP
                this.getServletContext().getRequestDispatcher("/catalog.jsp").forward(request, response);
                return;
			}
		}catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Returns the productitem for the given product id,if it is in the vector
     */
   
    private ProductItem getProductItem(Vector products,String productIDToAdd){
        int size=products.size();
        for(int i=0; i<size; i++){
            ProductItem item=(ProductItem)products.elementAt(i);
            if(item.getProductID().equals(productIDToAdd)){
               return item;
            }
       }
       return null;
   }
	public String getServletInfo() {
		return "The Catalog servlet adds products to the user's " +
		"cart and prints the catalog.";

	}
}