The following article shows how to perform Session Tracking Using an HTTP Servlet.

In order to create an HTTP servlet to perform session tracking you can proceed as follows.

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class SessionServlet extends HttpServlet {

  protected void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    // Get the current session or create a new one if it doesn't exist
    HttpSession session = request.getSession(true);

    // Get the current session ID
    String sessionId = session.getId();

    // Check if the session is new or not
    boolean isNewSession = session.isNew();

    // Set some session attributes
    session.setAttribute("username", "John");
    session.setAttribute("language", "English");

    // Get some session attributes
    String username = (String) session.getAttribute("username");
    String language = (String) session.getAttribute("language");

    // Print the session information
    response.getWriter().println("<h1>Session Tracking Example</h1>");
    response.getWriter().println("<p>Session ID: " + sessionId + "</p>");
    response.getWriter().println("<p>Is New Session: " + isNewSession + "</p>");
    response.getWriter().println("<p>Username: " + username + "</p>");
    response.getWriter().println("<p>Language: " + language + "</p>");

In this example, we have created a servlet class named SessionServlet that extends HttpServlet. So, in the doGet method, we get the current session using request.getSession(true). This will either return the existing session or create a new one if it doesn’t exist. We then get the session ID using session.getId() and check if the session is new or not using session.isNew().

Also, we set some session attributes using session.setAttribute(name, value) and get some session attributes using session.getAttribute(name).

Finally, we print the session information using the response.getWriter().println() method.

In order to test this servlet, you can simply access the servlet URL from a web browser. Each time you access the URL, a new session will be created and the session information will be printed. If you close the browser and access the URL again, a new session will be created and the session ID will be different. Another example with specific requirements is here.

To summarize, session tracking is useful when you want to maintain state information between multiple requests from the same client. It allows you to store user-specific information on the server and retrieve it later when needed.

Further Reading

Understanding Enterprise Java Beans

Java Practice Exercise