This is a simple servlet that uses session tracking and * Cookies to count the number of times a client session has * accessed this servlet. */ public class Counter extends HttpServlet { // Define our counter key into the session static final String COUNTER_KEY = "Counter.count"; /** *
Performs the HTTP GET operation * * @param req The request from the client * @param resp The response from the servlet */ public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, java.io.IOException { // Get the session object for this client session. // The parameter indicates to create a session // object if one does not exist HttpSession session = req.getSession(true); // Set the content type of the response resp.setContentType("text/html"); // Get the PrintWriter to write the response java.io.PrintWriter out = resp.getWriter(); // Is there a count yet? int count = 1; Integer i = (Integer) session.getValue(COUNTER_KEY); // If a previous count exists, set it if (i != null) { count = i.intValue() + 1; } // Put the count back into the session session.putValue(COUNTER_KEY, new Integer(count)); // Print a standard header out.println(""); out.println("
"); out.println("Initialize the servlet. This is called once when the * servlet is loaded. It is guaranteed to complete before any * requests are made to the servlet * * @param cfg Servlet configuration information */ public void init(ServletConfig cfg) throws ServletException { super.init(cfg); } /** *
Destroy the servlet. This is called once when the servlet * is unloaded. */ public void destroy() { super.destroy(); } }