gistfile1.pde

@WebServlet(name="AsyncServlet", urlPatterns={"/AsyncServlet"}, asyncSupported=true)
public class AsyncServlet extends HttpServlet {
   
   protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8"); 
        try {
            System.out.println("Starting doGet");
            AsyncContext ac = request.startAsync();
            //<- Why doing that : HttpServletRequest.getAsyncContext()
            request.getServletContext().setAttribute("asyncContext", ac); 
            ac.addListener(new AsyncListener() {

                @Override
                public void onComplete(AsyncEvent event) throws IOException {
                    System.out.println("onComplete");
                }

                @Override
                public void onTimeout(AsyncEvent event) throws IOException {
                    System.out.println("onTimeout");
                }

                @Override
                public void onError(AsyncEvent event) throws IOException {
                    System.out.println("onError");
                }

                @Override
                public void onStartAsync(AsyncEvent event) throws IOException {
                    System.out.println("onStartAsync");
                }
            });

            System.out.println("Do some stuff in doGet ...");


            // Hum, One ScheduledThreadPoolExecutor per request? Also execute will be fire right away...
            // might want to put some TimeUnit here and make sure shutdown gets invoked.
            ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(10); 
            executor.execute(new MyAsyncService(ac));

            // Two threads may manipulate the same Request/Response objects at the same time, hence this is not 
            // recommended to manipulate the request after startAsync() gets invoked.   
            System.out.println("Some more stuff in doGet ...");                
        } finally { 
        }
    }

    class MyAsyncService implements Runnable {
        AsyncContext ac;

        public MyAsyncService(AsyncContext ac) {
            this.ac = ac;
            System.out.println("Dispatched to " + "\"MyAsyncService\"");
        }

        @Override
        public void run() {
            System.out.println("Some long running process in \"MyAsyncService\"");
            ac.complete();
        }
    }
}