31.4 Integrating JAX-RS with EJB Technology and CDI

JAX-RS works with Enterprise JavaBeans technology (enterprise beans) and Contexts and Dependency Injection for Java EE (CDI).

In general, for JAX-RS to work with enterprise beans, you need to annotate the class of a bean with @Path to convert it to a root resource class. You can use the @Path annotation with stateless session beans and singleton POJO beans.

The following code snippet shows a stateless session bean and a singleton bean that have been converted to JAX-RS root resource classes.

@Stateless
@Path("stateless-bean")
public class StatelessResource {...}

@Singleton
@Path("singleton-bean")
public class SingletonResource {...}

Session beans can also be used for subresources.

JAX-RS and CDI have slightly different component models. By default, JAX-RS root resource classes are managed in the request scope, and no annotations are required for specifying the scope. CDI managed beans annotated with @RequestScoped or @ApplicationScoped can be converted to JAX-RS resource classes.

The following code snippet shows a JAX-RS resource class.

@Path("/employee/{id}")
public class Employee {
    public Employee(@PathParam("id") String id) {...}
}

@Path("{lastname}")
public final class EmpDetails {...}

The following code snippet shows this JAX-RS resource class converted to a CDI bean. The beans must be proxyable, so the Employee class requires a nonprivate constructor with no parameters, and the EmpDetails class must not be final.

@Path("/employee/{id}")
@RequestScoped
public class Employee {
    public Employee() {...}

    @Inject
    public Employee(@PathParam("id") String id) {...}
}

@Path("{lastname}")
@RequestScoped
public class EmpDetails {...}