Thread unsafe - make it safe

Question

class PageServlet extends HttpServer {
    String id;
    public void doGet(HttpServletRequest request,
              HttpServletResponse response)
    throws ServletException, IOException
        id = request.getParameter("ID");
        out.println("Your id is "+id);
The id variable used above is shared by all the threads created.
How can i make id local to each thread. Such that each thread uses its initialized value, without moving the variable id inside the doGet method?
(Note: This is problems reflects a problem in a big sized servlet. That is the reason why just moving the id inside doGet method does not solve the problem.)
Any suggestions?
Thank you

Answer 1

I dont know what you mean hereThe servlet container (Tomcat, whatever) creates an HttpServletRequest object for each user request. This object exists roughly from the moment the user's browser sends a request to your server to the time your servlet finishes sending HTML back to the browser (so, a fraction of a second). It's common to pass control between different servlets within the server. So servlets use the request as a shared bucket to store various intermediate values. They are stored as attributes (effectively a HashMap).
public void doGet(HttpServletRequest request, HttpServletResponse response) {
    String id = request.getParameter("ID"); // This gets the value that the browser sent
    request.setAttribute("id", id);
    doSomeStuff(request, ...);
private void doSomeStuff(HttpServletRequest request, ...) {
    String id = (String) request.getAttribute("id");
}