EJBFactory 设计方法。

一、EJBFactory 设计类如下：

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

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


import javax.jms.JMSException;
import javax.jms.ObjectMessage;
import javax.jms.Queue;
import javax.jms.QueueConnection;
import javax.jms.QueueConnectionFactory;
import javax.jms.QueueSender;
import javax.jms.QueueSession;
import javax.jms.Session;
import javax.naming.Context;
/**
 * EJB Home Factory, maintains a simple hashmap cache of EJBHomes
 * For a production implementations, exceptions such as NamingException
 * can be wrapped with a factory exception to futher simplify
 * the client.
 */
public class EJBHomeFactory
{
	private Map ejbHomes;
	private static EJBHomeFactory aFactorySingleton;
	Context ctx;
	private Log4j log = new Log4j(Constant.ModuleType.SETTLEMENT, this);
	/**
	 * EJBHomeFactory private constructor.
	 */
	private EJBHomeFactory() throws NamingException
	{
		try
		{
			ctx = new InitialContext();
			this.ejbHomes = Collections.synchronizedMap(new HashMap());
		}
		catch (Exception e)
		{
			//can't do anything about this
			//client will catch errors upon trying to
			//do a lookup
		}
	}
	/**
	 * Returns the singleton instance of the EJBHomeFactory
	 * The sychronized keyword is intentionally left out the
	 * as I don't think the potential to intialize the singleton
	 * twice at startup time (which is not a destructive event)
	 * is worth creating a sychronization bottleneck on this
	 * VERY frequently used class, for the lifetime of the
	 * client application.
	 */
	public static EJBHomeFactory getFactory() throws IException
	{
		try
		{
			if (EJBHomeFactory.aFactorySingleton == null)
			{
				EJBHomeFactory.aFactorySingleton = new EJBHomeFactory();
			}
		}
		catch (NamingException e)
		{
			throw new IException("EJBHomeFactory NamingException", e);
		}
		return EJBHomeFactory.aFactorySingleton;
	}
	/**
	 * Lookup and cache an EJBHome object using a home class.
	 * Assumes that the JNDI name of the EJB Home being looked for
	 * is the same as the fully qualified class name of the
	 * same EJB Home.
	 * If EJB-REF tags are being used externally, then the classname
	 * of the EJB Home can be mapped to the actual JNDI name of the
	 * deployed bean transaprently at deployment time.
	 * If EJB-REF tags are not used, then the EJB's must be deployed
	 * with JNDI names equal to their fully qualified home interfaces.
	 */
	public EJBHome lookUpHome(Class homeClass) throws IException
	{
		EJBHome anEJBHome;
		String jndiName = "";
		anEJBHome = (EJBHome) this.ejbHomes.get(homeClass);
		try
		{
			String ResourceReference = homeClass.getName().substring(homeClass.getName().lastIndexOf(".") + 1, homeClass.getName().length());
			if (anEJBHome == null)
			{
				anEJBHome = EJBObject.getEJBHome(ResourceReference);
				//anEJBHome = (EJBHome) PortableRemoteObject.narrow(ctx.lookup(jndiName), AccountHome.class);

				this.ejbHomes.put(homeClass, anEJBHome);
				log.info(ResourceReference + " lookup successfully.");
			}
		}
		catch (ClassCastException e)
		{
			throw new IException("EJBHomeFactory ClassCastException", e);
		}
		catch (NamingException e)
		{
			throw new IException("EJBHomeFactory ClassCastException", e);
		}
		catch (Exception e)
		{
			Log.print(jndiName + " home not found - " + "Is bean registered with JNDI?: " + e.toString());
		}
		return anEJBHome;
	}
}

 二、获取EJB实例的方法：

		try
		{

			TransCurrentDepositHome home =
				(TransCurrentDepositHome) EJBHomeFactory.getFactory().lookUpHome(TransCurrentDepositHome.class);
			transCurrentDepositFacade = (TransCurrentDeposit) home.create();
		}
		catch (RemoteException e)
		{
			throw e;
		}
		catch (IException e)
		{
			e.printStackTrace();
			throw new RemoteException();
		}
		catch (CreateException e)
		{
			e.printStackTrace();
			throw new RemoteException();
		}

 三、仅供参考设计EJBFactory的方法。