ServiceLocatorGenerics : a ServiceLocator for finding EJB 2 via JNDI, using Java 5 Generics. It makes it possible to invoke : MyEJBHome remoteHome = ServiceLocatorGenerics.getEjbRemoteHome("jndiName", MyEJBHome.class); without having to do a casting

_ServiceLocatorException.java

package fr.husta.ejbutils.servicelocator;

public class ServiceLocatorException
        extends Exception
{

    private static final long serialVersionUID = 1L;

    public ServiceLocatorException()
    {
        super();
    }

    public ServiceLocatorException(String message)
    {
        super(message);
    }

    public ServiceLocatorException(String message, Throwable throwable)
    {
        super(message, throwable);
    }

    public ServiceLocatorException(Throwable throwable)
    {
        super(throwable);
    }

}

ServiceLocatorGenerics.java

package fr.husta.ejbutils.servicelocator;

import javax.ejb.EJBHome;
import javax.ejb.EJBLocalHome;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.rmi.PortableRemoteObject;

/**
 * ServiceLocator for EJB 2 with Java 5 Generics.
 * <br>
 * See <a href="http://www.amazon.com/Effective-Java-Edition-Joshua-Bloch/dp/0321356683">Java Effective 2nd Edition</a> :
 * <ul>
 *  <li>Chapter 5 - Generics</li>
 *  <ul>
 *   <li>Item 27 : Favor generic methods.</li>
 *  </ul>
 * </ul>
 * 
 * @since J2EE 1.3
 * @since Java 5
 * @see http://java.sun.com/blueprints/corej2eepatterns/Patterns/ServiceLocator.html
 * @see https://forums.oracle.com/thread/1159595
 */
public class ServiceLocatorGenerics
{

    private Context initialContext;

    /**
     * 
     * @throws NamingException
     */
    public ServiceLocatorGenerics() throws NamingException
    {
        super();
        initialContext = new InitialContext();
    }

    /**
     * 
     * @param context
     * @throws NamingException
     */
    public ServiceLocatorGenerics(final Context context) throws NamingException
    {
        super();
        this.initialContext = context;
    }

    /**
     * Permet de simplifier l'ecriture de la recuperation d'un EJB Home par un ServiceLocator.
     * <br>
     * Exemple :
     * <pre>
     *  ServiceLocatorGenerics serviceLocator = new ServiceLocatorGenerics();
     *  MyEJBHome remoteHome = serviceLocator.getEjbRemoteHome("test", MyEJBHome.class);
     * </pre> 
     * 
     * @param jndiName JNDI name for EJB.
     * @param ejbHomeClass
     * @return
     * @throws ServiceLocatorException 
     */
    @SuppressWarnings("unchecked")
    public <E extends javax.ejb.EJBHome> E getEjbRemoteHome(String jndiName, Class<E> ejbHomeClass)
            throws ServiceLocatorException
    {
        Object remoteInterface = null;
        EJBHome ejbHome = null;
        try
        {
            remoteInterface = initialContext.lookup(jndiName);
            // test possible : 
            // only narrow if necessary
            // if (java.rmi.Remote.class.isAssignableFrom(narrowTo))
            ejbHome = (EJBHome) PortableRemoteObject.narrow(remoteInterface, ejbHomeClass);
            if (ejbHome == null)
            {
                throw new ServiceLocatorException("Impossible d'obtenir l'interface home pour  " + jndiName);
            }
        }
        catch (NamingException ne)
        {
            throw new ServiceLocatorException(ne);
        }
        return (E) ejbHome;
    }

    /**
     * Permet de simplifier l'ecriture de la recuperation d'un EJB Local Home par un ServiceLocator.
     * <br>
     * Exemple :
     * <pre>
     *  ServiceLocatorGenerics serviceLocator = new ServiceLocatorGenerics();
     *  MyEJBLocalHome localHome = serviceLocator.getEjbLocalHome("testLocal", MyEJBLocalHome.class);
     * </pre> 
     * 
     * @param jndiName JNDI name for EJB.
     * @param ejbLocalHomeClass
     * @return
     * @throws ServiceLocatorException 
     */
    @SuppressWarnings("unchecked")
    public <E extends javax.ejb.EJBLocalHome> E getEjbLocalHome(String jndiName, Class<E> ejbLocalHomeClass)
            throws ServiceLocatorException
    {
        Object localInterface = null;
        EJBLocalHome ejbLocalHome = null;
        try
        {
            localInterface = initialContext.lookup(jndiName);
            ejbLocalHome = (EJBLocalHome) localInterface;
            if (ejbLocalHome == null)
            {
                throw new ServiceLocatorException("Impossible d'obtenir l'interface local home pour " + jndiName);
            }
        }
        catch (NamingException ne)
        {
            throw new ServiceLocatorException(ne);
        }
        return (E) ejbLocalHome;
    }

    /**
     * Acces generique a l'annuaire JNDI.
     * 
     * @param jndiName
     * @return
     * @throws ServiceLocatorException Principalement en cas de NamingException.
     * @see {@link javax.naming.Context#lookup(String)}.
     */
    public Object getRemoteInterface(final String jndiName) throws ServiceLocatorException
    {
        Object remoteInterface;
        try
        {
            remoteInterface = initialContext.lookup(jndiName);
        }
        catch (Exception ex)
        {
            throw new ServiceLocatorException(ex);
        }
        return remoteInterface;
    }

}