其实有上面的结论,无外乎现在java里面的新技术已经几乎能完全取代ejb的优点,而克服ejb的缺点,entity bean和有状态的session bean已经机乎被视为垃圾,hibernate和spring大行其到,看看最进n期《programmer》中篇幅的比重就知道了。本来我个人的感觉是hibernate取代了entity bean,spring取代了session bean,但是ejb的远程调用用hibernate和spring的架构还取代不了,可是在最近的一期《programmer》中我发现了Hessian!更爽的是,发现了spring原来可以和Hessian结合使用!看来真的可以say byebye to ejb了。
看到这么振奋人心的消息,怎么能不亲自试验一下呢,于是上http://www.caucho.com/以迅雷不及掩耳盗铃之势下载了Hessian的src jar和bin jar。create一个工程,把这些相关的jar统统扔进去,配置和coding就可以开始了。首先,开了如下几个包:
whao.test.hessian.server
放远程服务的接口
whao.test.hessian.server.impl
放远程服务的实现类
whao.test.hessian.client
放客户端应用
1. whao.test.hessian.server中写一个MyService接口:
Java代码
- /*
- * Created on 2005-7-25
- *
- */
- package whao.test.hessian.server;
- /**
- * @author Hao Wei
- *
- */
- public interface MyService {
- public String doSomething(String s);;
- }
2. whao.test.hessian.server.impl中写一个实现类
Java代码
- /*
- * Created on 2005-7-25
- *
- */
- package whao.test.hessian.server.impl;
- import whao.test.hessian.server.MyService;
- /**
- * @author Hao Wei
- *
- */
- public class MyServiceImpl implements MyService {
- /* (non-Javadoc);
- * @see whao.test.hessian.server.MyService#doSomething(java.lang.String);
- */
- public String doSomething(String s); {
- return "HAHAHA: " + s;
- }
- }
3. 配置远程服务
Hessian的远程服务要配置成servlet,配置如下:
Java代码
- <servlet>
- <servlet-name>myservice</servlet-name>
- <servlet-class>com.caucho.hessian.server.HessianServlet</servlet-class>
- <load-on-startup>1</load-on-startup>
- <init-param>
- <param-name>service-class</param-name>
- <param-value>whao.test.hessian.server.impl.MyServiceImpl</param-value>
- </init-param>
- </servlet>
- <servlet-mapping>
- <servlet-name>myservice</servlet-name>
- <url-pattern>/myservice</url-pattern>
- </servlet-mapping>
这样,当启动了这个web应用,这个远程服务就以url http://localhost:8080/test_web/myservice 的形式发布了。然后就是开发客户端来调用这个远程服务。
Java代码
- /*
- * Created on 2005-7-25
- *
- */
- package whao.test.hessian.client;
- import whao.test.hessian.server.MyService;
- import com.caucho.hessian.client.HessianProxyFactory;
- /**
- * @author Hao Wei
- *
- */
- public class TestMain {
- public static void main(String[] args); throws Exception {
- HessianProxyFactory proxyFactory = new HessianProxyFactory();;
- MyService service = (MyService); proxyFactory.create(MyService.class,
- "http://localhost:8080/test_web/myservice");;
- System.out.println(service.doSomething("xixixixi"););;
- System.out.println("ok!");;
- }
- }
运行一把,显示
HAHAHA:xixixi
ok!
不错不错,纯Hessian的远程调用就这样搞定了。继续研究《programmer》看到上面介绍用spring的远程访问解决方案来访问ejb的远程服务。什么?spring还有远程解决方案?没听说过嘛,看了《programmer》上的介绍,发现是真的。那么既然spring能访问ejb的远程服务,那么能访问Hessian的远程服务么?打开spring.jar看看,居然发现了名曰org.springframework.remoting.caucho.HessianProxyFactoryBean的类!夏昕真不厚道啊,再他的spring中文教程中居然匿掉了spring里这么好的东西!于是打开sping英文版reference,终于找到了用spring配置Hessian客户端的方法:
Java代码
- <bean id="myService" class="org.springframework.remoting.caucho.HessianProxyFactoryBean">
- <property name="serviceUrl">
- <value>
- http://localhost:8080/test_web/myservice
- </value>
- </property>
- <property name="serviceInterface">
- <value>whao.test.hessian.server.MyService</value>
- </property>
- </bean>
然后客户端就可以这么玩啦:
Java代码
- /*
- * Created on 2005-7-25
- *
- */
- package whao.test.hessian.client;
- import whao.test.hessian.server.MyService;
- import whao.util.spirng.SpringBeanFactory;
- import com.caucho.hessian.client.HessianProxyFactory;
- /**
- * @author Hao Wei
- *
- */
- public class TestMain {
- public static void main(String[] args); throws Exception {
- testWithSpring();;
- }
- public static void testWithSpring();{
- MyService service = (MyService);SpringBeanFactory.getBean("myService");;
- System.out.println(service.doSomething("lllllllll"););;
- System.out.println("ok!");;
- }
- public static void testWithoutSpring(); throws Exception {
- HessianProxyFactory proxyFactory = new HessianProxyFactory();;
- MyService service = (MyService); proxyFactory.create(MyService.class,
- "http://localhost:8080/test_web/myservice");;
- System.out.println(service.doSomething("xixixixi"););;
- System.out.println("ok!");;
- }
- }
执行一下,输出是:
HAHAHA:lllllllll
ok!
spring真是个好东东,呵呵,其中的SpringBeanFactory是这样实现的:
Java代码
- /*
- * Created on 2005-7-25
- *
- */
- package whao.util.spirng;
- import javax.servlet.ServletContext;
- import org.apache.commons.logging.Log;
- import org.apache.commons.logging.LogFactory;
- import org.springframework.context.ApplicationContext;
- import org.springframework.context.support.FileSystemXmlApplicationContext;
- import org.springframework.web.context.support.WebApplicationContextUtils;
- /**
- * @author Hao Wei
- *
- */
- public class SpringBeanFactory {
- private static final Log log = LogFactory.getLog(SpringBeanFactory.class);;
- private static ApplicationContext ctx = null;
- public static Object getBean(ServletContext context, String beanID); {
- log.info("beanID=" + beanID);;
- ApplicationContext ac = WebApplicationContextUtils
- .getWebApplicationContext(context);;
- return ac.getBean(beanID);;
- }
- public static Object getBean(String beanID);{
- if(ctx == null);{
- ctx = new FileSystemXmlApplicationContext(
- "D:\\whao-work\\src\\test_web\\test_web\\WEB-INF\\applicationContext.xml");;
- }
- return ctx.getBean(beanID);;
- }
- }
看到sping.jar的包org.springframework.remoting.caucho中还有另外两个类叫HessianClientInterceptor和HessianServiceExporter,看来貌似hessian服务端也可以和spring结合,还有客户端的Interceptor估计可以实现对远程服务的AOP,要继续研究一下了,待续吧