EJB study

出处：（http://yuyu.blogdriver.com/yuyu/1061697.html）

写一个EJB的步骤：

 

 

 

1.     声明远程接口

 

 

 

public interface HelloWorld extends EJBObject

 

 

 

{

 

 

 

      public String sayHello(String words) throws RemoteException;

 

 

 

}

 

 

 

2.     添加工厂

 

 

 

2.public interface HelloWorldHome extends EJBHome

 

 

 

{

 

 

 

      public HelloWorld create() throws CreateExceptio , RemoteException;

 

 

 

}

 

 

 

3.     实现bean

 

 

 

public class HelloWorldBean implements SessionBean

 

 

 

   {

 

 

 

           //接口中的方法

 

 

 

           public void ejbActivate(){}

 

 

 

           public void ejbRemove() {}

 

 

 

           public void ejbPassivate() {}

 

 

 

           public void setSessionContext( SessionContext ctx) {}

 

 

 

           public void ejbCreate() throws CreateException {}

 

 

 

           //以下是要完成接口HelloWorld 中的业务方法

 

 

 

           public String sayHello(String words) throws RemoteException

 

 

 

{

 

 

 

System.out.println(“liuyd say to everybody”+words);

 

 

 

                      return words;

 

 

 

}

 

 

 

}

 

 

 

4.     对类进行编译

 

 

 

5.     编写 EJB 部署说明文件

 

 

 

<?xml version="1.0" ?>

 

 

 

  <!DOCTYPE ejb-jar (View Source for full doctype...)>

 

 

 

- <ejb-jar>

 

 

 

- <enterprise-beans>

 

 

 

- <session>

 

 

 

  <ejb-name>HelloWorld</ejb-name>

 

 

 

  <home> HelloWorldHome</home>

 

 

 

  <remote> HelloWorld</remote>

 

 

 

  <ejb-class> HelloWorldBean</ejb-class>

 

 

 

  <session-type>Stateless</session-type>

 

 

 

  <transaction-type>Container</transaction-type>

 

 

 

  </session>

 

 

 

  </enterprise-beans>

 

 

 

  </ejb-jar>

 

 

 

 

 

 

 

6.     将Bean打包(包括所有类、部署文件)

 

 

 

7.     产生EJB容器代码(EJB容器自己完成对文件在EJB中的部署)

 

 

 

8.     部署EJB

 

 

 

9.     编写客户端

 

 

 

public class SimpleEJBClient

 

 

 

{

 

 

 

        private static final String JNDI_NAME = "HelloWorld";

 

 

 

        public static void main(String[] args)

 

 

 

        throws Exception

 

 

 

        {

 

 

 

     try                

 

 

 

{

 

 

 

                //jndi properties

 

 

 

                Properties h = new Properties();

 

 

 

              h.put(Context.INITIAL_CONTEXT_FACTORY,

 

 

 

                "weblogic.jndi.WLInitialContextFactory");

 

 

 

              h.put(Context.PROVIDER_URL,

 

 

 

                "t3://localhost:7001");

 

 

 

               //lookup jndi initial context

 

 

 

                InitialContext ctx = new InitialContext(h);

 

 

 

                //lookup home

 

 

 

                Object obj = ctx.lookup(JNDI_NAME);

 

 

 

//cast home

 

 

 

HelloWorldHome          home =(HelloWorldHome)PortableRemoteObject.narrow(obj, elloWorldHome.class);

 

 

 

        //create the bean

 

 

 

        Object ejbObj = home.create();

 

 

 

        //cast the bean to our interface

 

 

 

        HelloWorld simpleEJB =           (HelloWorld)PortableRemoteObject.narrow(ejbObj, HelloWorld.class);

 

 

 

        /call bean's method

 

 

 

        System.out.println("Calling Simple EJB: " + simpleEJB.sayIt());

 

 

 

        }

 

 

 

catch (Exception e)

 

 

 

        {

 

 

 

             System.out.println(e.getMessage());

 

 

 

                e.printStackTrace();

 

 

 

    }       

 

 

 

      }

 

 

 

}