ex7_4.txt

j2ee core design patterns

Example 7.4 		ServiceLocator.java: Implementing EJB Service Locator 
Strategy
package com.corej2eepatterns.servicelocator;

// imports
public class ServiceLocator {
    . . . 
    // look up a local home given the JNDI name for the
    // local home
    public EJBLocalHome getLocalHome(String jndiHomeName) 
    throws ServiceLocatorException {
        EJBLocalHome localHome = null;
        try {
            if (cache.containsKey(jndiHomeName)) {
                localHome = (EJBLocalHome)
                    cache.get(jndiHomeName);
            } else {
                localHome = (EJBLocalHome)
                    initialContext.lookup(jndiHomeName);
                cache.put(jndiHomeName, localHome);
            }
        } catch (NamingException nex) {
            throw new ServiceLocatorException(nex);
        } catch (Exception ex) {
            throw new ServiceLocatorException(ex);
        }
        return localHome;
    }

    // lookup a remote home given the JNDI name for the
    // remote home
    public EJBHome getRemoteHome(
        String jndiHomeName, Class homeClassName)
    throws ServiceLocatorException {
        EJBHome remoteHome = null;
        try {
            if (cache.containsKey(jndiHomeName)) {
                remoteHome =
                    (EJBHome) cache.get(jndiHomeName);
            } else {
                Object objref =
                    initialContext.lookup(jndiHomeName);
                Object obj = PortableRemoteObject.
                    narrow(objref, homeClassName);
                remoteHome = (EJBHome)obj;
                cache.put(jndiHomeName, remoteHome);
            }
        } catch (NamingException nex) {
            throw new ServiceLocatorException(nex);
        } catch (Exception ex) {
            throw new ServiceLocatorException(ex);
        }
        return remoteHome;
    }

    . . .
}