Object through out application

[Rudradutt Joshi]

Hello there,

I am developing a web application, now what I want to do is to use a HASHMAP through out the application, by mean when server starts to server stops and I should be able to play with it mean while also.

Thanks for your time.

PS : session is not available to me always
[ December 16, 2008: Message edited by: rudradutt joshi ]

[Martijn Verburg]

Hi there,

I'm afraid I don't understand your question. Are you saying that you want to be able to control the stopping and starting of the server from your code?

[Rudradutt Joshi]

NO,
what I want to do is,
create an Object which's scope is application.
I want to create an Object (suppose myObject).
Now when I request for Object say

 myObject.get("keyName")   

if it will be null, than I will create value for "keyName" and add it to Object

 myObject.put("keyName","Hello")   

now I want this Object to be available throughout the application like HttpSession
but I dont have any HTTP request,response to create a session with my current status.

[ December 16, 2008: Message edited by: rudradutt joshi ]
[ December 16, 2008: Message edited by: rudradutt joshi ]

[Martijn Verburg]

Oh, OK, I think I understand now, you're looking to put items into the application scope.

Have you had a look at the ServletContext class?

e.g.:

getServletContext().setAttribute("counter", new foo.Counter())

Also, moving this to Servlet forum.

[Rudradutt Joshi]

so what I tried is

  public class FenceMap extends HttpServlet {
 
    public static final Logger log = Logger.getLogger(FenceMap.class);
    private Map fenceMap;
 
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        setMap();
    }
 
    private void setMap() {
        try {
            fenceMap = new HashMap(0);
            fenceMap.put("1", 1);
            getServletContext().setAttribute("fenceMap", fenceMap);
            log.info("fenceMap Initialized key 1 value :"+getFenceMap("1"));
            log.info("key 1 value :"+getFenceMap("1"));
        } catch (Exception e) {
            log.error("fenceMap Not Initialized :" + e.getMessage());
        }
    }
 
    public Object getFenceMap(String key) {
        if (!((HashMap) getServletContext().getAttribute("fenceMap")).containsKey(key)) {
        }
        return (Object) ((HashMap) getServletContext().getAttribute("fenceMap")).get(key);
    }
 
    public void addToMap(String key, Object value) {
        ((HashMap) getServletContext().getAttribute("fenceMap")).put(key, value);
    }
 
    public void nullKey(String key) {
        ((HashMap) getServletContext().getAttribute("fenceMap")).remove(key);
    }
}  

which will be loaded on start up

now how will I found the servletContext from another bean like

class abc{
  public static void main(String args[]) {
         log.info(new FenceMap().getFenceMap("1"));
    }
 } 

[ December 17, 2008: Message edited by: rudradutt joshi ]

[Bauke Scholtz]

public static FenceMap getCurrentInstance() {
    return getServletContext().getAttribute("fenceMap");
}

That said, it doesn't necessarily have to be a servlet. That's a very odd design. Just let an HttpServlet (or, better, a ServletContextListener) create an independent FenceMap object and place it in the desired scope.

Also, testing servlets as a Java Application (with main()) isn't going to work. Test it as a servlet in a real webcontainer. Use an appserver and a webbrowser or JUnit.
[ December 17, 2008: Message edited by: Bauke Scholtz ]

[Rudradutt Joshi]

Thank you, for your help.

I had redesign the ServletContextListener for the application, but now as it is happening, I have to accept some times request from TCP/UDP ports also.
In such cases it throws

java.lang.NullPointerException

as no servletcontext is available.

So i want a solution of that.

regards,
Rudradutt

[Bauke Scholtz]

Originally posted by rudradutt joshi:
In such cases it throws

as no servletcontext is available.

So i want a solution of that.

Did you read my last comment anyway?

Also, testing servlets as a Java Application (with main()) isn't going to work. Test it as a servlet in a real webcontainer. Use an appserver and a webbrowser or JUnit.

You need to test it in a webcontainer.