remotefactory.java

Spring2.0宝典

package lee;

import java.util.Map;
import java.util.HashMap;
import javax.ejb.EJBObject;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.rmi.PortableRemoteObject;
import javax.ejb.CreateException;
import java.rmi.RemoteException;

/**
 * @author  yeeku.H.lee [e-mail]
 * @version  1.0
 * <br>Copyright (C), 2005-2008, yeeku.H.Lee
 * <br>This program is protected by copyright laws.
 * <br>Program Name:
 * <br>Date: 
 */

public class RemoteFactory
{
	private static RemoteFactory instance;

	//用这个HashMap来缓存查找到的EJBRemote
	private Map remoteInterfaces;
	private Context context;

	private RemoteFactory() throws NamingException
	{
		remoteInterfaces = new HashMap();
		context = getInitialContext();
	}

	public static synchronized RemoteFactory getInstance() throws NamingException
	{
		//不是线程安全的,但已经足够 || 加上synchronized会变成线程安全,但性能会下降
		if (instance == null)
		{
			instance = new RemoteFactory();
		}
		return instance;
	}

	private EJBObject lookup(String jndiName, Class homeInterfaceClass)
		throws NamingException,CreateException,RemoteException
	{
		EJBObject remoteInterface = null;
		remoteInterface = (EJBObject)remoteInterfaces.get(homeInterfaceClass);
        //如果该接口不存在，则执行JNDI查找
        if (remoteInterface == null)
		{
			Object obj = context.lookup(jndiName);
			MyEJBHome homeInterface = (MyEJBHome)PortableRemoteObject.narrow(obj, homeInterfaceClass);
			remoteInterface = homeInterface.create();
            //如果这是个新的引用对象,则将该对象保存入缓存
			remoteInterfaces.put(homeInterfaceClass, remoteInterface);
		}
        return remoteInterface;
	}

	
	//避免每次都重新初始化Context
    private Context getInitialContext()
	{
		if (context == null)
		{
			//如果不是在J2EE程序里，还需要属性文件才能正确查找到InitialConext()
			try
			{
				context = new InitialContext();
			}
			catch (NamingException ne)
			{
				ne.printStackTrace();
			}
		}
		return context;
	}
}