java.lang.ClassCastException: $Proxy99 cannot be cast

问题

I am using JBoss4.2.2 and java6.

The deployed ear's name is apa.ear

In a servlet I have the following code line:

placeBid = (PlaceBid) context.lookup("apa/"
  + PlaceBid.class.getSimpleName() + "/remote");

I have a generated jboss-app.xml like this:

<jboss-app>
  <loader-repository>apa:app=ejb3</loader-repository>
</jboss-app>

When trying to get the PlaceBid via the context I get this exception

java.lang.ClassCastException: $Proxy99 cannot be cast to se.nextit.actionbazaar.buslogic.PlaceBid

The PlaceBid interface looks like this:

@Remote
public interface PlaceBid {
 Long addBid(String userId, Long itemId, Double bidPrice);
}

When I run the example coming with EJB3 in action it works. EJB3 in action sample code comes with ant building. I want to use Maven so I have rearranged the code some.

However, I don't understan what I am doing wrong here. I have some thoughts about the jboss-app.xml file. I am not sure of how its content should look like.

Grateful for any help.

Best wishes Lasse

回答1:

As a first step, try the following:

Object obj = context.lookup("apa/" + PlaceBid.class.getSimpleName() + "/remote");
System.out.println("Object = " + obj.getClass().getName());
System.out.println("Interfaces = " + Arrays.toString(obj.getClass().getInterfaces()));

It will tell you what the actual stub concrete class is and what interfaces it implements. This may then give you enough of a hint to work out what's going wrong.

Also presumably your bean is defined as:

@Stateless
public class MyPlaceBidBean implements PlaceBid {
    ...
}

i.e. it implements the PlaceBid interface?

回答2:

If context is of type javax.naming.Context (or InitialContext), then the problem is that you have a missing call to PortableRemoteObject.narrow:

placeBid = (PlaceBid) PortableRemoteObject.narrow(context.lookup("apa/"
  + PlaceBid.class.getSimpleName() + "/remote", PlaceBid.class);

This is required by the EJB specification for remote interfaces. If you use a reference instead (@EJB or ejb-ref), the container will handle the narrow for you.

来源：https://stackoverflow.com/questions/2576510/java-lang-classcastexception-proxy99-cannot-be-cast