Jersey servlet class is constructed with every request

Question

I am working on a very simple setup of tomcat and jersey servlet. I just noticed that servlet class constructed for every request. What I have read about servlets is that they are init() once, service() multiple times and destroy() once. Why is it not the case for my setup.

Below is my web.xml

<!DOCTYPE web-app PUBLIC
        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
    <display-name>Archetype Created Web Application</display-name>

    <servlet>
        <servlet-name>contact-dropbox-servlet</servlet-name>
        <servlet-class>
            org.glassfish.jersey.servlet.ServletContainer
        </servlet-class>
        <init-param>
            <param-name>jersey.config.server.provider.packages</param-name>
            <param-value>com.inbhiwadi.services</param-value>
        </init-param>
        <init-param>
            <param-name>com.sun.jersey.api.json.POJOMappingFeature</param-name>
            <param-value>true</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>contact-dropbox-servlet</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
</web-app>

And my servlet entry class looks like below:

@Path("/contact")
@Slf4j
public class ContactDropboxService {

    private ContactDAO contactDAO;

    private NotificationPublisher notificationPublisher;

    public ContactDropboxService() {
        ApplicationContext context = new ClassPathXmlApplicationContext("Spring-Module.xml");
        this.contactDAO = (ContactDAO) context.getBean("contactDAO");
        this.notificationPublisher = (NotificationPublisher) context.getBean("notificationPublisher");
        log.debug("ContactDropboxService constructed one more time");
    }

    @GET
    public String greet() {
        log.info("Welcome to InBhiwadi contact services!");
        return "Welcome to InBhiwadi contact services";
    }

    @POST
    @Path("/drop")
    public Response create(Contact contact) {

        log.debug("Received contact is : [{}]", contact.toString());
        contactDAO.create(contact);
        notificationPublisher.publish(contact.toString());
        return Response.accepted("Contact dropped in box").build();
    }
}

What should I do to have single instance of ContactDropboxService serving multiple requests?

score 3 · Accepted Answer · answered Dec 02 '17 at 02:28

3

By default Jersey will instantiate resource class per request. If you want to have just one instance of resource class you should annotate it with @Singleton. For more details you can check out this SO question

answered Dec 02 '17 at 02:28

alexdzot

175
14

I am curious about how is it going to handle concurrent requests. Will multiple threads be forked if another requests comes before first is served. If yes, then is concurrency to be handled manually? – Kuldeep Yadav Dec 02 '17 at 10:02

Jersey servlet class is constructed with every request

1 Answers1