How to set session timeout dynamically in java web applications?

Question

Hi,

I need to give my user a web interface to change the session timeout interval. So, different installations of the web application would be able to have different timeouts for their sessions, but their web.xml cannot be different.

Is there a way to set the session timeout programatically, so that I could use, say, ServletContextListener.contextInitialized() to read the configured interval and set it upon application startup?

Thanks a lot.

Answer 1

Is there a way to set the session timeout programatically

There are basically three ways to set the session timeout value:

• by using the session-timeout in the standard web.xml file ~or~
• in the absence of this element, by getting the server's default session-timeout value (and thus configuring it at the server level) ~or~
• programmatically by using the HttpSession. setMaxInactiveInterval(int seconds) method in your Servlet or JSP.

But note that the later option sets the timeout value for the current session, this is not a global setting.

Answer 2

Instead of using a ServletContextListener, use a HttpSessionListener. In the sessionCreated() method, you can set the session timeout programmatically.

public class MyHttpSessionListener implements HttpSessionListener{
  public void sessionCreated(HttpSessionEvent event){
    event.getSession().setMaxInactiveInterval(15*60); //in seconds
  }
  public void sessionDestroyed(HttpSessionEvent event){}
}

And don't forget to define the listener in the deployment descriptor:

<webapp>
...
  <listeners>
    <listener-class>com.example.MyHttpSessionListener</listener-class>
  </listeners>
</webapp>

Still, I would recommend creating different web.xml files for each application and defining the session timeout there:

<webapp>
...
  <session-config>
    <session-timeout>15</session-timeout> <!-- in minutes -->
  </session-config>
</webapp>