Singleton variables in Jersey web service

I have a RESTful web service based on JAX-RS and Jersey. I have a bunch of GET and POST Methods and inside of it I need "global" variables.

I have an initialization method with ServletContextListener and it's contextInitialized-Method for write some log files and do other stuff. In this method I want to declare variables which I can access from anywhere in my application.

here are my code:

    @WebListener    public class MyServletContextListener implements ServletContextListener {//these are the variables I need in my other methods        public String imagePath;        public int entryCount;        public int registeredUsers;        public Connection connection;        @Override        public void contextInitialized(ServletContextEvent servletContextEvent) {            System.out.println("initialization of service stared");            System.out.println("reading config...");            Configuration config = ConfigManager.readConfig("../service_config.xml");            this.imagePath = config.getImagePath();            System.out.println("try to get databse connection");            connection = ConnectionHelper.getConnection(config.getDbName(),                                                        config.getDbPassword(),                                                        config.getDbUser());            System.out.println("database connection successful established");            // here are some db actions...        }        @Override        public void contextDestroyed(ServletContextEvent servletContextEvent) {            System.out.println("shutdown service");        }    }

For example:At init, I read an config file, count some stats from database and read an image path-string for a directory out of my config file.

When a GET method is called, I want to read the String variable of the image path and increase a counter by 1.

@Path("/entries")public class EntryService {@GET    @Path("/images/{imageId}")    @Produces({"image/png"})    public Response getEntryImage(@PathParam("imageId") long imageId) {        String filePath = <* HERE I NEED THE IMAGE PATH FROM INIT *>;        File file = new File(filePath + imageId +".png");        if (file.exists()) {            Response.ResponseBuilder response = Response.ok((Object) file);            response.header("Content-Disposition", "attachment; filename=image_from_server.png");            return response.build();        } else {            Response.ResponseBuilder response = Response.status(204);            return response.build();        }    }}

How do I realize that? (I read something about EJB and Singleton-Annotation but didn't get it work).

If a library or component needs some extra dependencies in my pom.xml file, please tell me how to implement it.