About Pankaj Kumar
Before we jump into understanding what Async Servlet is, let’s try to understand why do we need it. Let’s say we have a Servlet that takes a lot of time to process, something like below.
LongRunningServlet.java
package com.journaldev.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/LongRunningServlet")public class LongRunningServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { long startTime = System.currentTimeMillis(); System.out.println("LongRunningServlet Start::Name=" + Thread.currentThread().getName() + "::ID=" + Thread.currentThread().getId()); String time = request.getParameter("time"); int secs = Integer.valueOf(time); // max 10 seconds if (secs > 10000) secs = 10000; longProcessing(secs); PrintWriter out = response.getWriter(); long endTime = System.currentTimeMillis(); out.write("Processing done for " + secs + " milliseconds!!"); System.out.println("LongRunningServlet Start::Name=" + Thread.currentThread().getName() + "::ID=" + Thread.currentThread().getId() + "::Time Taken=" + (endTime - startTime) + " ms."); } private void longProcessing(int secs) { // wait for given time before finishing try { Thread.sleep(secs); } catch (InterruptedException e) { e.printStackTrace(); } }} Source : http://www.javacodegeeks.com/2013/08/async-servlet-feature-of-servlet-3.html
