varren varren - 7 months ago 46
Java Question

How to list all registered JAX-RS Entity Providers in Jersey

Let's suppose i have simple jersey app with embedded jetty Demo project on github and essential code below.

Back in the days with jersey1 i had log messages:

мая 07, 2016 5:05:50 AM com.sun.jersey.api.core.PackagesResourceConfig init
INFO: Scanning for root resource and provider classes in the packages:
ru.varren
мая 07, 2016 5:05:50 AM com.sun.jersey.api.core.ScanningResourceConfig logClasses
INFO: Root resource classes found:
class ru.varren.MyResource
мая 07, 2016 5:05:50 AM com.sun.jersey.api.core.ScanningResourceConfig logClasses
INFO: Provider classes found:
class ru.varren.JsonProvider
мая 07, 2016 5:05:50 AM com.sun.jersey.server.impl.application.WebApplicationImpl _initiate
INFO: Initiating Jersey application, version 'Jersey: 1.19.1 03/11/2016 02:08 PM'


But now i am trying to work with jersey2 and thiere is no more log info. So, my question is how to list all registered JAX-RS Entity Providers. I don't care much where to list them. In
main
function or in some
@GET
MyResource
method. Probably i should change something in my setup or put logger boolean, but cant find it.

This is purely for testing purpose. Simple print of all providers classes will be enough for me. Cooler option is to print provider and accosiated
@Produces
and
@Consumes
MediaType.

MyResource.java

@Path("test")
public class MyResource {

@GET
@Produces({ MediaType.APPLICATION_JSON })
public Response getPersons() {
return Response.ok("[some data here]").build();
}

}


MyApplication.java

public class MyApplication {

public static void main(String[] args) throws Exception {
URI baseUri = UriBuilder.fromUri("http://localhost/").port(9998).build();
ResourceConfig config = new ResourceConfig(MyResource.class);
config.packages("ru.varren");
Server server = JettyHttpContainerFactory.createServer(baseUri, config, true);
server.join();
}

}


And gradle.build

dependencies {
compile 'org.glassfish.jersey.containers:jersey-container-servlet:2.22.2'
compile 'org.glassfish.jersey.containers:jersey-container-servlet-core:2.22.2'
compile 'org.glassfish.jersey.media:jersey-media-json-jackson:2.22.2'
compile 'org.glassfish.jersey.containers:jersey-container-jetty-http:2.22.2'

compile 'org.eclipse.jetty:jetty-server:9.1.0.M0'
compile 'org.eclipse.jetty:jetty-servlet:9.1.0.M0'
}

Answer

You can use an ApplicationEventListener, and on INITIAILZATION_FINISHED, you can get a set of resources and providers from the ApplicationEvent. For example

@Provider
public class ProviderLoggingListener implements ApplicationEventListener {

    @Override
    public void onEvent(ApplicationEvent event) {
        switch (event.getType()) {
            case INITIALIZATION_FINISHED: {
                Set<Class<?>> providers = event.getProviders();
                Set<Class<?>> resources = event.getResources();
                break;
            }
        }
    }

    @Override
    public RequestEventListener onRequest(RequestEvent requestEvent) {
        return null;
    }
}