EJB3(3)

如果一个远程接口有两个实现，需要用mappedName来区分
首先定义一个远程接口：

@Remote
public   interface  HelloRemote  {

    String sayHi(String name);
}

第一个实现：

@Stateless(mappedName = " hello " )
public   class  HelloBean  implements  HelloRemote  {

    public String sayHi(String name) {
        return "Hi " + name; 
    }
}

第二个实现：

@Stateless(mappedName = " hello2 " )
public   class  HelloBean2  implements  HelloRemote {

    public String sayHi(String name) {
        return "Hello " + name;
    }

}

两个无状态会话bean实现了同一个远程接口，但它们的mappedName不一样，还有它们各自重写了sayHi业务方法。部署EJB模块然后测试，首先是Servlet：

    @EJB(mappedName = " hello2 " )
     private  HelloRemote helloBean2;
    @EJB(mappedName = " hello " )
     private  HelloRemote helloBean;

然后是JSP：

<%
            InitialContext ctx  =   new  InitialContext();
            HelloRemote helloBean  =  (HelloRemote)ctx.lookup( " hello " );
            out.println(helloBean.sayHi( " Tom " ));
            HelloRemote helloBean2  =  (HelloRemote)ctx.lookup( " hello2 " );
            out.println( " <br> "   +  helloBean2.sayHi( " Tom " ));
%>

呵呵，远程调用也实现了多态