使用wicket-guice时的无限循环

Question

im using wicket since a couple of months now and i started to evluate wicket-guice recently. So im quite a guice noobie :)

Every page got a ServiceClass (lets call it DoService) which manages a number of Objects (ie User) ... Those objects also got an reference to that ServiceClass for some reasons.

public class page ... {
  @Inject
  private DoService doService;
}

public class DoService ... {
  private Collection<User> ... 
}

public class User {
   @Inject
   private DoService doService;
}

Im not quite sure, but i think the following exception occurs cause of the circular references of dependencies though i thought guice manages this all by itsself.

Whatever.....if you need more information to understand my problem pls ask :)

Thanks in advance

java.lang.StackOverflowError
     at java.lang.reflect.InvocationTargetException.<init>(InvocationTargetException.java:54)
     at WICKET_....DoService$$FastClassByCGLIB$$ce256f9.invoke(<generated>)
     at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:191)
     at org.apache.wicket.proxy.LazyInitProxyFactory$CGLibInterceptor.intercept(LazyInitProxyFactory.java:317)
     at WICKET_....DoService$$EnhancerByCGLIB$$d1f8934e.rollback(<generated>)
     at WICKET_c....DoService$$FastClassByCGLIB$$ce256f9.invoke(<generated>)
     at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:191)
......

Answer 1

I think your design is incorrect: a domain object should not contain references to services. You indeed have a circular dependency.

Answer 2

What Guice does here is to create a new User instance for every DoService instance and a new DoService instance for every User instance. I don't think that's what you want to archive here (apart from the questionable design). There are several ways around this issue:

1. Use appropriate Providers in your module
2. Use singleton scope in guice
3. Use guice only for one of these instanciations. Have one object create the other and supply itself to the other's constructor for back-reference.