| 1. Assume that logininfo [0] is the login name and the session name is created. If (rs_login.next ()){
Login_servlet.logger.info ("login verification successful"); // log4j
Onlineuser Olu = new onlineuser ();//
If (! Olu. existuser (logininfo [0]) {
Login_servlet.logger.info ("Repeated login ");
Return;
} Else {
Session. setmaxinactiveinterval (3000); // the lifecycle of the session
Session. setattribute (logininfo [0], Olu );
} 2. Listener code: onlineuser Package CN. WST. Common. online; Import javax. servlet. http. httpsessionbindingevent;
Import javax. servlet. http. httpsessionbindinglistener;
Import org. Apache. log4j. Logger; Import java. util .*;
/**
* @ Author wangshangting
*
* Purpose:
* Used to count the number of online users, prevent uniform account logon and exit account cancellation
*/
Public class onlineuser implements httpsessionbindinglistener {
// Private Static onlineuser instance = NULL; // Synchronized public static onlineuser getinstance () // Singleton mode, ensure that there is only one onlineuser instance
//{
// If (instance = NULL)
//{
// Instance = new onlineuser ();
//}
// Return instance;
//}
Static logger = logger. getlogger (onlineuser. Class. getname ());
Public onlineuser (){
}
Private Static vector users = new vector (); // static variable !!!!!!!!!!!!
Private int I = 1;
Public int getcount (){
Users. trimtosize ();
Return users. Capacity ();
}
Public Boolean existuser (string username ){
Users. trimtosize ();
Boolean existuser = true;
For (INT I = 0; I <users. Capacity (); I ++)
{
If (username. Equals (string) users. Get (I )))
{
Existuser = false;
Onlineuser.logger.info (users. Get (I ));
Onlineuser.logger.info ("repeated ");
Break;
}
}
Return existuser;
}
Public Boolean deleteuser (string username ){
Onlineuser.logger.info ("start to remove !! ");
Users. trimtosize ();
If (! Existuser (username )){
Int curruserindex =-1;
For (INT I = 0; I <users. Capacity (); I ++ ){
If (username. Equals (string) users. Get (I ))){
// Onlineuser.logger.info ("found ");
Curruserindex = I;
Break;
}
}
If (curruserindex! =-1 ){
Onlineuser.logger.info ("Remove:" + curruserindex );
Users. Remove (curruserindex );
Users. trimtosize ();
Return true;
}
}
Return false;
}
Public vector getonlineuser ()
{
Return users;
}
Public void valuebound (httpsessionbindingevent e ){
Users. trimtosize ();
Users. Add (E. getname ());
Onlineuser.logger.info (E. getname () + "/T log on to the system/t" + (new date ()));
Onlineuser.logger.info ("+" + I + "");
I ++;
For (INT I = 0; I <users. Size (); I ++ ){
Onlineuser.logger.info ("" + I + ":" + users. Get (I ));
}
System. Out. println ("number of online users:" + getcount ());
}
/**
*
*/
Public void valueunbound (httpsessionbindingevent e ){
Users. trimtosize ();
String username = E. getname ();
Deleteuser (username ); Onlineuser.logger.info (username + "/T exit system/t" + (new date ()));
Onlineuser.logger.info ("number of online users:" + getcount ());
}
} 3. Remember to live onlineuser before all servlets in Web. xml, <Listener>
<Listener-class> CN. WST. Common. Online. onlineuser </listener-class>
</Listener> Article Source: http://www.theserverside.com/discussions/thread.tss? Thread_id = 34076 |
