Inject EJBs

Use this when your business logic lives in Enterprise JavaBeans on a Jakarta EE server and you want to inject them with @EJB. Wicket components are not managed by the server, so the server ignores these annotations on them. The module wicketstuff-javaee-inject from WicketStuff looks the beans up in JNDI when a component is constructed.

If your server supports CDI, as every Jakarta EE server does, you can also inject stateless and singleton session beans with @Inject through wicket-cdi, without an extra module.

Add the dependency

<dependency>
    <groupId>org.wicketstuff</groupId>
    <artifactId>wicketstuff-javaee-inject</artifactId>
    <version>${wicketstuff.version}</version>
</dependency>

WicketStuff releases follow the Wicket version numbers: use the WicketStuff release that matches your Wicket version. The module is maintained by the WicketStuff community, not by the Apache Wicket project, so check that a release exists for your Wicket version.

Register the injector

WicketApplication.java

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

Inject a session bean

OrderService.java

@Stateless
public class OrderService {
    public List<Order> openOrders() { /* ... */ }
}

OrdersPage.java

public class OrdersPage extends WebPage {

    @EJB
    private OrderService orders;

    public OrdersPage() {
        add(new ListView<Order>("orders", () -> orders.openOrders()) {
            @Override
            protected void populateItem(ListItem<Order> item) {
                item.add(new Label("number", item.getModel().map(Order::getNumber)));
            }
        });
    }
}

The field holds a serializable proxy, not the bean, so the page can be stored between requests. The proxy looks the bean up again after deserialization.

The module also handles two other annotations:

Choose the JNDI names

By default the injector looks up @EJB fields under java:comp/env/ followed by the name of the annotation, or the fully qualified class name of the field type when the name is empty. Most servers bind session beans under the portable global names instead. Pass a naming strategy that builds those names:

getComponentInstantiationListeners().add(
    new JavaEEComponentInjector(this, new ModuleJndiNamingStrategy()));

The strategies are in package org.wicketstuff.javaee.naming and its subpackage global. Your server logs the JNDI names of each session bean when it deploys the application; pick the strategy that matches them.

Stateful session beans

A stateful session bean belongs to one user. The injector keeps one instance per HTTP session for fields whose type is annotated with @Stateful, or whose @EJB annotation has description = "stateful".