pricerbean.java

JAVA 光盘操作说明 是解压包,直接解压就可以了

package examples;

import javax.ejb.*;
import java.rmi.RemoteException;
import java.util.*;
import javax.naming.*;
import javax.rmi.PortableRemoteObject;
/**
 * Stateless Session Bean which computes prices based
 * upon a set of pricing rules.  The pricing rules are
 * deployed with the bean as environment properties.
 */
public class PricerBean implements SessionBean {
   
	// Constants used for reading properties
	public static final String ENV_DISCOUNT = "java:comp/env/PricerProps/DISCOUNT_";
	public static final String ENV_TAX_RATE = "java:comp/env/PricerProps/TAX_RATE";
  
	/*
	 * Although this is a stateless session bean, we
	 * do have state - the session context.  Remember
	 * that stateless session beans can store state, they
	 * just can't store state on behalf of particular
	 * clients.
	 */
	private SessionContext ctx;

	//----------------------------------------------------
	// Begin business methods
	//----------------------------------------------------

	/**
	 * Computes the total price of a cart.  This includes
	 * subtotal and taxes.  Sets the appropriate cart
	 * fields.  We expose this coarse-grained method to
	 * avoid network roundtrips for pricing individual
	 * parts of a cart.
	 */
	public void price(Cart cart) throws PricerException, RemoteException {
		priceSubtotal(cart);
		priceTaxes(cart);
	}

	/**
	 * Computes the subtotal price for a set of Books the
	 * customer is interested in.  The subtotal takes into
	 * account the price of each Book the customer wants,
	 * the quantity of each Book, and any discounts the
	 * customer gets.  However, the subtotal ignores taxes.
	 *
	 * @param quote All the data needed to compute the
	 * subtotal is in this parameter.
	 */
	private void priceSubtotal(Cart cart) throws PricerException, RemoteException {
		System.out.println("PricerBean.priceSubtotal() called");
		
		/*
		 * Customers with certain names get discounts.
		 * The discount rules are stored in the
		 * environment properties that the bean is
		 * deployed with.
		 * 
		 * Get the name of this customer.
		 */
		User user = getUser(cart.getOwner());
		String customerName = user.getCustomerID();
		double percentDiscount = 0;
        boolean flag=true;
        int i=0;
		try {
            Context initCtx = new InitialContext();
            while(flag) {
                
                /*
                 * Get the next discount equation from
                 * the environment properties.  A
                 * discount equation has the form
                 * "<name>=<% discount>".  For example,
                 * "Ed Roman=50" means that the
                 * Customer whose name is "Ed Roman"
                 * gets a 50% discount.
                 */
                String discount = (String) initCtx.lookup(ENV_DISCOUNT + i++);
                System.out.println("Discount:"+discount);
                
                /*	
                 * Break the equation up into
                 * customer name, discount
                 */	
                StringTokenizer tokens = new StringTokenizer(discount, "=", false);
                String discountCustomerName = tokens.nextToken();
                percentDiscount = Double.valueOf(tokens.nextToken()).doubleValue();
                
                /*
                 * If this discount applies to this
                 * customer, then stop.  Otherwise,
                 * move on to the next discount
                 * equation.
                 */
                if (discountCustomerName.equals(customerName)) {
                    break;
                }
                System.out.println("Pricer.priceSubtotal(): " + customerName + " gets a " + percentDiscount + "% discount.");
            }
		}catch(javax.naming.NameNotFoundException ne){
            flag=false;
        }catch (Exception e) {   
            e.printStackTrace();
            System.out.println("Pricer.priceSubtotal(): " + customerName + " doesn't get a discount.");
        }

		/*
		 * Now we know how much discount to apply.  The
		 * next step is to apply the discount to each
		 * Book the customer is interested in.
		 *
		 * We need to get the price and quantity of each
		 * Book the customer wants.  The cart object
		 * stores this information in individual cart
		 * line-items.  Each line-item has price and
		 * quantity information for a single Book.
		 */

		/*
		 * First, get the Line Items contained within the
		 * Cart.
		 */
		Enumeration lineItems = Collections.enumeration(cart.getAll());

		/*
		 * Compute the subtotal
		 */
		double subTotal = 0;
		try {
			/*
			 * For each line item...
			 */
			while (lineItems.hasMoreElements()) {
				LineItem li = (LineItem) lineItems.nextElement();

				/*
				 * Get the price of the line item...
				 */
				double basePrice = li.getBasePrice();

				/*
				 * Set the discount for this line item...
				 */
				li.setDiscount(basePrice * (percentDiscount/100));
			
				/*
				 * Apply the discount...
				 */
				double aggregatePrice =
				basePrice - (basePrice * percentDiscount/100);

				/*
				 * And add the price to the subtotal.
				 */
				subTotal += aggregatePrice;
			}
	
			cart.setSubtotal(subTotal);
		}catch (Exception e) {
			throw new PricerException(e.toString());
		}
	}
        
    /**
     * This method uses UserManager session bean to retrive user information.
     * User has customer id, name password and address.
     *@param customerid id of the customer
     */
    private User getUser(String customerId){
            try{
                Context ctx = new InitialContext();
                UserManagerHome userManagerHome = (UserManagerHome)
                    PortableRemoteObject.narrow(
                        ctx.lookup("UserManagerHome"), UserManagerHome.class);
                UserManager userManager=userManagerHome.create();
                
                /* 
                 * Usermanager returns user object for the given customerid
                 */ 
                User user=userManager.getUser(customerId);
                return user;
            }catch (Exception e) {
                throw new EJBException(e);
            }
    }
            
	/**
	 * Computes the taxes on a Cart.
	 * Since the taxes are based on the subtotal, we assume
	 * that the subtotal has already been calculated.
	 */
	private void priceTaxes(Cart cart) throws PricerException, RemoteException {
		System.out.println("PricerBean.priceTaxes() called");

		/*
		 * Compute the taxes
		 */
		try {
			Context initCtx = new InitialContext();
			String taxRateStr = (String) initCtx.lookup(ENV_TAX_RATE);
			double taxRate = Double.valueOf(taxRateStr).doubleValue();
                        System.out.println("Tax Rate:"+taxRate);
			double subTotal = cart.getSubtotal();
			cart.setTaxes((taxRate/100) * subTotal);
		}
		catch (Exception e) {
			e.printStackTrace();
			throw new PricerException(e.toString());
		}
	}

	//----------------------------------------------------
	// End business methods
	//----------------------------------------------------

	//----------------------------------------------------
	// Begin EJB-required methods.  The methods below are
	// called by the Container, and never called by client
	// code.
	//----------------------------------------------------

	public void ejbCreate() throws RemoteException {
		System.out.println("ejbCreate() called.");
	}
  
	public void ejbRemove() {
		System.out.println("ejbRemove() called.");
	}
       public void ejbActivate() {
		System.out.println("ejbActivate() called.");
	}

	public void ejbPassivate() {
		System.out.println("ejbPassivate() called.");
	}
	

	public void setSessionContext(SessionContext ctx) {
		System.out.println("setSessionContext() called");
		this.ctx = ctx;
	}

	//----------------------------------------------------
	// End EJB-required methods
	//----------------------------------------------------
}