Spring访问EJB3.0的SessionBean方法

Spring2.*提供了一个访问EJB的方法，即

“org.springframework.ejb.access.LocalStatelessSessionProxyFactoryBean”和

“org.springframework.ejb.access.SimpleRemoteStatelessSessionProxyFactoryBean”

两个FactoryBean,一个用来访问本地的，一个用来访问远程的无状态SessionBean。但是这两个FactoryBean

只能针对EJB2.0的无状态SessionBean，所以在配置是必须提供SessionBean的Home接口。而在EJB3.0中已经没有了Home接口（或者说被隐藏起来了）。为了访问EJB3.0的无状态Session Bean就只好自己写一个了。

package com.cyf.spring.ext;



import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;

import org.apache.log4j.Logger;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.jndi.JndiTemplate;

public class SlsbFactoryBean implements FactoryBean {
  
   private static Logger log=Logger.getLogger(SlsbFactoryBean.class);
   private JndiTemplate jndiTemplate;
    private Context ejbCtx;
    private String jndiName;
    private Object ejbobj;
    public synchronized Object getEjbObject(){
    	if (ejbobj==null){
    		if (jndiTemplate == null || jndiTemplate.getEnvironment() == null) {
				throw new LookupSlsbException("jndiTemplate is required!");
			}
			try {
				ejbCtx = new InitialContext(jndiTemplate.getEnvironment());
			} catch (Exception e) {
				throw new LookupSlsbException(
						"can't initial a javax.naming.InitialContext ");
			}
			if (jndiName==null){
				throw new LookupSlsbException("jndiName is required!");
			}
			try {
				ejbobj=ejbCtx.lookup(jndiName);
				return ejbobj;
			} catch (NamingException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				return null;
			}
    	}else{
    		return ejbobj;
    	}
    }          
	public Object getObject() throws Exception {
		// TODO Auto-generated method stub
        return getEjbObject();		
	}

	public Class getObjectType() {
		// TODO Auto-generated method stub
		return null;
	}

	public boolean isSingleton() {
		// TODO Auto-generated method stub
		return false;
	}

	public JndiTemplate getJndiTemplate() {
		return jndiTemplate;
	}

	public void setJndiTemplate(JndiTemplate jndiTemplate) {
		log.info("setting jndiTemplate....");
		this.jndiTemplate = jndiTemplate;
	}

	public String getJndiName() {
		return jndiName;
	}

	public void setJndiName(String jndiName) {
		log.info("setting jndiName");
		this.jndiName = jndiName;
	}


}

这个类实现了Spring的FactoryBean接口

/*
 * Copyright 2002-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.factory;

/**
 * Interface to be implemented by objects used within a {@link BeanFactory}
 * which are themselves factories. If a bean implements this interface,
 * it is used as a factory for an object to expose, not directly as a bean
 * instance that will be exposed itself.
 *
 * <p><b>NB: A bean that implements this interface cannot be used as a
 * normal bean.</b> A FactoryBean is defined in a bean style, but the
 * object exposed for bean references is always the object that it creates.
 *
 * <p>FactoryBeans can support singletons and prototypes, and can
 * either create objects lazily on demand or eagerly on startup.
 *
 * <p>This interface is heavily used within the framework itself, for
 * example for the AOP {@link org.springframework.aop.framework.ProxyFactoryBean}
 * or the {@link org.springframework.jndi.JndiObjectFactoryBean}.
 * It can be used for application components as well; however,
 * this is not common outside of infrastructure code.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @since 08.03.2003
 * @see org.springframework.beans.factory.BeanFactory
 * @see org.springframework.aop.framework.ProxyFactoryBean
 * @see org.springframework.jndi.JndiObjectFactoryBean
 */
public interface FactoryBean {

	Object getObject() throws Exception;

	
	Class getObjectType();

	
	boolean isSingleton();

}

请注意FactoryBean的“getObject()”方法，这个方法将会在Spring客户端调用ApplicationContext.getBean()的时候被调用，或者说getObject()代理了getBean()方法，下面将会看一个例子。所以我在getObject()方法中去lookup EJB3.0的sessionbean。

再来看下Spring配置文件。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd">
	<bean id="propertyConfigurer"
		class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
		<property name="location">
			<value>WEB-INF/classes/jndi.properties</value>
		</property>
	</bean>
	<bean id="jndiTemplate"
		class="org.springframework.jndi.JndiTemplate">
		<property name="environment">
			<props>
				<prop key="java.naming.provider.url">
					${java.naming.provider.url}
				</prop>
				<prop key="java.naming.factory.initial">
					${java.naming.factory.initial}
				</prop>
				<prop key="java.naming.factory.url.pkgs">
					${java.naming.factory.url.pkgs}
				</prop>
			</props>
		</property>
	</bean>
	<bean id="RemoteDAO" class="com.cyf.spring.ext.SlsbFactoryBean">
		<property name="jndiTemplate">
			<ref local="jndiTemplate" />
		</property>
		<property name="jndiName" value="CommonDAOImpl/remote" />
	</bean>
</beans>

SlsbFactoryBean只需要设置jndi属性模板和jndiName，不需要EJB2.0的home接口了

调用的例子：

package com.cyf.spring.ext;

import java.util.List;

import javax.faces.context.FacesContext;

import org.apache.log4j.Logger;
import org.springframework.context.ApplicationContext;
import org.springframework.web.jsf.FacesContextUtils;

import com.book.business.CommonDAO;
import com.bookstore.admin.actions.PressAction;

public class TestSlsbFactoryBean {
 //在JSF环境中得到SpringApplicationContext
 private static ApplicationContext ctx = FacesContextUtils
   .getWebApplicationContext(FacesContext.getCurrentInstance());
 private static Logger log = Logger.getLogger(TestSlsbFactoryBean.class);

 public void testBean() {
  //getBean(RemoteDAO)返回的结果就是调用SlsbFactoryBean.getObject()方法返回的结果
  CommonDAO dao = (CommonDAO)ctx.getBean("RemoteDAO");
  List list = dao.getObjByEQL("select count(p) from Press p", null, -1, -1);
  long size = (Long) list.get(0);
  log.info(size);
 }
}