通过Listner获得当前的用户个数
package listener; import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener; public class OnlineUsers implements ServletContextListener,HttpSessionListener{
private int count;
private ServletContext cxt;
@Override
public void sessionCreated(HttpSessionEvent arg0) {
// TODO Auto-generated method stub
count++;
cxt.setAttribute("count", new Integer(count));
} @Override
public void sessionDestroyed(HttpSessionEvent arg0) {
// TODO Auto-generated method stub
count--;
cxt.setAttribute("count", new Integer(count));
} @Override
public void contextDestroyed(ServletContextEvent arg0) {
// TODO Auto-generated method stub
cxt = null;
} @Override
public void contextInitialized(ServletContextEvent arg0) {
// TODO Auto-generated method stub
cxt = arg0.getServletContext();
} }