Jboss Ejb3.0 Interceptor

 


Interceptor为拦截器，可以监听程序的整个程序或方法。从多个程序理解问题往往比较容易，我就在自己写的HelloWorld 程序的基础上增加了Interceptor .



有如下几个程序：Hello.java , HelloLocal.java , HelloRemote.java , HelloBean.java, TracingInterceptor.java



Client.java



重点在HelloBean.java, TracingInterceptor.java 这两个程序。




 



 



 


Hello.java



/**



 * @author roson



 *



 * 2005-4-10



 */



package org.jboss.tutorial.stateless.bean;




 


public interface Hello {



    public void hello();



    public String hello2();



}




 



 



 


HelloLocal.java



/**



 * @author roson



 *



 * 2005-4-10



 */



package org.jboss.tutorial.stateless.bean;




 


import javax.ejb.Local;




 


@Local



public interface HelloLocal extends Hello{




 


}




 



 



 


HelloRemote.java



/**



 * @author roson



 *



 * 2005-4-10



 */



package org.jboss.tutorial.stateless.bean;




 


import javax.ejb.Remote;




 


@Remote



public interface HelloRemote extends Hello{




 


}




 



 



 


HelloBean.java



/**



 * @author roson



 *



 * 2005-4-10



 */



package org.jboss.tutorial.stateless.bean;




 


import javax.ejb.InvocationContext;



import javax.ejb.Stateless;



import javax.ejb.AroundInvoke;



import javax.ejb.Interceptor;




 


@Stateless



@Interceptor("org.jboss.tutorial.stateless.bean.TracingInterceptor")



public class HelloBean implements HelloRemote,HelloLocal {



    public void  hello()



    {



        System.out.println("Hello roson");



    }



   



    public String hello2()



    {



        return "are you ok";



    }



   



    @AroundInvoke



    public Object myBeanInterceptor(InvocationContext ctx) throws Exception



    {



        if (ctx.getMethod().getName().equals("hello"))



        {



           System.out.println("*** hello: " );



        }



        if (ctx.getMethod().getName().equals("hello2"))



        {



           System.out.println("*** hello2: " );



        }



       return ctx.proceed();



    }



}




 


说明：



@Interceptor("org.jboss.tutorial.stateless.bean.TracingInterceptor") 定义了一个自己定义的Interceptor 。



也可以有多个 Interceptor 格式如下



@Interceptors ({"org.jboss.TracingInterceptor", "org.jboss..OtherInterceptor"})



以上两种监视整个class的情况，要做的更细点就是单独监视拦截每个方法，需要另外写个方法：



@AroundInvoke



    public Object 方法名可以任意(InvocationContext ctx) throws Exception



{



}




 



 



 


TracingInterceptor.java



package org.jboss.tutorial.stateless.bean;




 


import javax.ejb.AroundInvoke;



import javax.ejb.InvocationContext;




 


public class TracingInterceptor {




 


   @AroundInvoke



   public Object log(InvocationContext ctx) throws Exception



   {



      System.out.println("*** TracingInterceptor intercepting");



      long start = System.currentTimeMillis();



      try



      {



         return ctx.proceed();



      }



      catch(Exception e)



      {



         throw e;



      }



      finally



      {



         long time = System.currentTimeMilli