Share variables between JAX-RS requests

Question

I have what I think is a very basic question about JAX-RS but I somehow can\'t easily find the answer.

I am trying to refactor a REST service which uses a \"standard

Answer 1

You can use a listener for init the cache and set to the context as attribute before the web application start. something like the following:

package org.paulvargas.shared;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class CacheListener implements ServletContextListener {

    public void contextInitialized(ServletContextEvent sce) {
        Map dummyCache = new HashMap();
        dummyCache.put("greeting", "Hello Word!");

        ServletContext context = sce.getServletContext();
        context.setAttribute("dummyCache", dummyCache);
    }

    public void contextDestroyed(ServletContextEvent sce) {
        ServletContext context = sce.getServletContext();
        context.removeAttribute("dummyCache");
    }

}

This listener is configured in the web.xml.

    org.paulvargas.shared.CacheListener


    restSdkService
    
        org.apache.wink.server.internal.servlet.RestServlet
    
    
        applicationConfigLocation
        /WEB-INF/application
    


    restSdkService
    /rest/*

You can use the @Context annotation for inject the ServletContext and retrieving the attribute.

package org.apache.wink.example.helloworld;

import java.util.*;

import javax.servlet.ServletContext;
import javax.ws.rs.*;
import javax.ws.rs.core.*;

import org.apache.wink.common.model.synd.*;

@Path("/world")
public class HelloWorld {

    @Context
    private ServletContext context;

    public static final String ID = "helloworld:1";

    @GET
    @Produces(MediaType.APPLICATION_ATOM_XML)
    public SyndEntry getGreeting() {

        Map dummyCache = 
                       (Map) context.getAttribute("dummyCache");

        String text = dummyCache.get("greeting");

        SyndEntry synd = new SyndEntry(new SyndText(text), ID, new Date());
        return synd;
    }

}