wicket-user-guide/src/main/asciidoc/jee/jee_1.adoc

WicketStuff provides a module called wicketstuff-javaee-inject that contains component instantiation listener _JavaEEComponentInjector_. If we register this listener in our application we can use standard EJB annotations to inject dependencies into our Wicket components.

To register a component instantiation listener in Wicket we must use _Application_'s method _getComponentInstantiationListeners_ which returns a typed collection of _IComponentInstantiationListeners_. 

The following initialization code is taken from project _EjbInjectionExample_: 

[source,java]
----
public class WicketApplication extends WebApplication
{    	
       //Constructor...

	@Override
	public void init()
	{
		super.init();
		getComponentInstantiationListeners().add(new JavaEEComponentInjector(this));		
	}	
}
----

In this example the object that we want to inject is a simple class containing a greeting message:

[source,java]
----
@ManagedBean
public class EnterpriseMessage {
	public String message = "Welcome to the EJB world!";
}
----

Please note that we have used annotation ManagedBean to decorate our object. Now to inject it into the home page we must add a field of type EnterpriseMessage and annotate it with annotation _EJB_:

[source,java]
----
public class HomePage extends WebPage {
	
	@EJB
	private EnterpriseMessage enterpriseMessage;
	//getter and setter for enterpriseMessage...
	
	public HomePage(final PageParameters parameters) {
		super(parameters);
	
		add(new Label("message", enterpriseMessage.message));
	}
}
----

That is all. We can point the browser to the home page of the project and see the greeting message injected into the page:

image::../img/EjbInjectionExample.png[]