How to make a JAX-RS annotated singleton class EAGERLY instantiated

Question

I am using Jax-RS 2.0 with Jersey 2.22.1 and Java SE 8, deployed in Tomcat 8.0.30. I have the POJO annotated with the appropriate JAX-RS annotations, and its working as expected. I have also annotated the POJO with @Singleton. The class gets lazily instantiated as a singleton, which is the expected behavior of @Singleton. But I would like to instantiated the class eagerly, at application startup. Is there a way to do that? I have looked at the @Startup annotation but unfortunately, that is part of the EJB package and I am not using EJB's (nor would I like to import the EJB jar file).

I am also using the Springframework 4.2.4 which would by default eagerly instantiate singletons when using the @Service or @Component annotations but unfortunately, I cannot use those annotations on a JAX-RS POJO (this is why the class extends from SpringBeanAutowiringSupport.

I have attached the java code but since its working as expected I'm not sure that would add anything useful.

import javax.inject.Singleton;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.GET;
import javax.ws.rs.Produces;
import javax.ws.rs.Consumes;
import javax.ws.rs.FormParam;
import javax.ws.rs.core.MediaType;
import org.xxx.profile.util.GeneralUtil;
import org.xxx.profile.util.WebServiceLogger;
import org.xxx.profile.util.datatransfer.AccountDTO;
import org.xxx.profile.web.exception.RestException;
import org.xxx.profile.web.exception.FailureResponse;
import org.springframework.web.context.support.SpringBeanAutowiringSupport;


@Singleton
@Path( "account" )
public class AccountWebService  extends SpringBeanAutowiringSupport{


    @Autowired
    private AccountLogic accountLogic;

    @Autowired
    protected SimpleParser simplerParser;


    @GET
    @Path("get/{id: [a-zA-Z][a-zA-Z_0-9]*}")
    @Produces( MediaType.APPLICATION_JSON )
    @Consumes( MediaType.APPLICATION_JSON )
    public AccountDTO retrieveAccount(@PathParam("id") String customerId) throws RestException {
        try {
            return accountLogic.retrieveAccount(customerId);
        }
        catch(Exception e){
            String transactionID = GeneralUtil.getUniqueID();
            WebServiceLogger.severe( transactionID, "Unable to retrieve an account for the customerId: " + customerId, e, this.getClass() );
            throw new RestException( new FailureResponse( FailureResponse.Status.FAIL, "add user friendly message here", transactionID ), e );
        }
    }

}

Answer 1

See Jersey 2.22.1 User Guide:

If you want to use Jersey Spring DI support you will need to add the jersey-spring3 module into the list of your dependencies:

<dependency>
    <groupId>org.glassfish.jersey.ext</groupId>
    <artifactId>jersey-spring3</artifactId>
    <version>2.22.1</version>
</dependency>

It seems to work for Spring 4, too. See Question 21443088