I need to make a servlet that shows at the client browser a page with the value of a variable

in the servlet. This variable is increasing each three seconds. The first time that the client

browser calls to the servlet, a page is showed and is colled (at the servlet) the

"show_counter" method, that is inside a bucle and it should refresh the page on the client

browser each three seconds to show the new value of the counter.

This program is not working. Can you say me if must use multithread or wath is the

problem?



Thanks



This is the source code of the program:




import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;



public class Master extends HttpServlet

{

int started = 0;

int counter;

long last_time = 0;

long current_time = 0;





public void init (ServletConfig config) throws

ServletException

{

super.init (config);

counter = 0;

last_time = System.currentTimeMillis();

}





protected void doGet (HttpServletRequest req,

HttpServletResponse res)

throws ServletException, IOException

{

if (started == 0)

{

started = 1;



StringBuffer buffer = new StringBuffer();



buffer.append (" ");

buffer.append (" ");

buffer.append (" Pantalla regenerada. Paso ");

buffer.append (Integer.toString (counter));

buffer.append (" ");



res.setContentType ("text/html");

res.setContentLength (buffer.length());

res.setHeader ("pragma", "no-cache");

res.getOutputStream().print (buffer.toString());



show_counter(req, res);

}

}





protected void show_counter (HttpServletRequest req,

HttpServletResponse res)

throws IOException

{

while (counter < 20)

{

current_time = System.currentTimeMillis();

if ((current_time - last_time) >= 3000)

{

StringBuffer buffer = new StringBuffer();



last_time = current_time;

counter++;



buffer.append (" ");

buffer.append (" counter desde el servidor ");

buffer.append (" Pantalla regenerada. Paso ");

buffer.append (Integer.toString (counter));

buffer.append (" ");



res.setContentType ("text/html");

res.setContentLength (buffer.length());

res.setHeader ("pragma", "no-cache");

res.getOutputStream().print (buffer.toString());

}

}

}





}