How to make Jersey work with Dagger dependency injection?

Question

Jersey normally uses HK2 dependency injection, but I would like to use Jersey with Dagger 2. Both Dagger and HK2 implement JSR 330, which I have taken as evidence that this should be possible without too much effort. I found ways to make Jersey work with CDI (e.g. Weld), Spring DI and Guice, but I can't find anything on Dagger.

To provide some context: I'm running a Grizzly–Jersey server in an SE environment, not in an EE container. My Maven project has com.google.dagger:dagger and org.glassfish.jersey.containers:jersey-container-grizzly2-http as dependencies, but not org.glassfish.jersey.inject:jersey-hk2, since I want to replace HK2 with Dagger.

The resource classes look like this:

@Path("/example")
public final class ExampleResource {

    private final Dependency dependency;

    @Inject
    public ExampleResource(final Dependency dependency) {
        this.dependency = Objects.requireNonNull(dependency);
    }

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Example getExample() {
        return this.dependency.giveExample();
    }

}

And the Dagger component could e.g. be defined as follows:

@Component
public interface Application {

    public ExampleResource exampleEndpoint();
    public XyzResource xyzEndpoint();
    // etc.

}

So that the main method would look similar to:

public final class Main {

    public static void main(final String[] args) {
        final Application application = DaggerApplication.create();
        final URI baseUri = UriBuilder.fromUri("http://0.0.0.0/").port(80).build();
        final ResourceConfig resourceConfig = new ResourceConfig();
        // how to initialize `resourceConfig` using `application`?
        final HttpServer httpServer = GrizzlyHttpServerFactory
                .createHttpServer(baseUri, resourceConfig, false);
        try {
            httpServer.start();
        } catch (final IOException ex) {
            ...
        }
    }

}

Running the application immediately results in an exception: IllegalStateException: InjectionManagerFactory not found. It seems that a Dagger implementation of this factory is needed.

My question is: how to integrate Dagger with Jersey?

Answer 1

You need to implement an InjectionManagerFactory that will return an InjectionManager delegating to Dagger and have it registered as a service by putting an entry in META-INF/services, similar to the hk2 one here: https://github.com/jersey/jersey/blob/master/inject/hk2/src/main/resources/META-INF/services/org.glassfish.jersey.internal.inject.InjectionManagerFactory but referencing your own implementation.