托管bean EJB注入

Question

i'm having many managed beans and was wondering if i could create a UtilClass where i put my services calls (@EJB). I've already tried it but i'm having a NullPointerException. this is how my UtilClass and my managed bean look like:

public class UtilClass{
@EJB
private static MyFirstEjbLocal myFirstService;
@EJB
private static  MySecondEjbLocal mySecondService;
//other services
//getters

 }


public class MyManagedBean{
   public String myMethod(){

   UtilClass.getMyFirstService.doSomethingInDB();

   return null;
  }
}

Answer 1

I would suggest you to do the following, since apparently you are having a lot of services and want to have them grouped together, you can create an " abstract " bean and make your managed bean extend such " abstract " bean, in this way you can access the EJB's in a structural and safe way, the following code will explain what I mean:

public class MyAbstractBean{
  @EJB
  protected MyFirstEjbLocal myFirstService;
  @EJB
  protected  MySecondEjbLocal mySecondService;
  // All your other EJB's here
  ...
  // All other variables and methods you could need
}


public class MyManagedBean
   extends MyAbstractBean{

    public String myMethod1(){

      myFirstService.doSomethingInDB();
      return "";

    }

    public String myMethod2(){

      mySecondService.doSomethingInDB();
      return "";

    }
}

Please refer to JavaEE5 EJB FAQ if you need to clarify more concepts on the matter.