How to set session timeout dynamically in Java web applications?

I need to give my user 开发者_JAVA百科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?

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

(or since Servlet version 3.0 you can use @WebListener annotation instead).

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>

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.

As another anwsers told, you can change in a Session Listener. But you can change it directly in your servlet, for example.

getRequest().getSession().setMaxInactiveInterval(123);

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.

your question is simple, you need session timeout interval should be configurable at run time and configuration should be done through web interface and there shouldn't be overhead of restarting the server.

I am extending Michaels answer to address your question.

Logic: You need to store configured value in either .properties file or to database. On server start read that stored value and copy to a variable use that variable until server is UP. As config is updated update variable also. Thats it.

Expaination

In MyHttpSessionListener class 1. create a static variable with name globalSessionTimeoutInterval.

2. create a static block(executed for only for first time of class is being accessed) and read timeout value from config.properties file and set value to globalSessionTimeoutInterval variable.

3. Now use that value to set maxInactiveInterval

4. Now Web part i.e, Admin configuration page

   a. Copy configured value to static variable globalSessionTimeoutInterval.

   b. Write same value to config.properties file. (consider server is restarted then globalSessionTimeoutInterval will be loaded with value present in config.properties file)

5. Alternative .properties file OR storing it into database. Choice is yours.

Logical code for achieving the same

public class MyHttpSessionListener implements HttpSessionListener 
{
  public static Integer globalSessionTimeoutInterval = null;

  static
  {
      globalSessionTimeoutInterval =  Read value from .properties file or database;
  }
  public void sessionCreated(HttpSessionEvent event)
  {
      event.getSession().setMaxInactiveInterval(globalSessionTimeoutInterval);
  }

  public void sessionDestroyed(HttpSessionEvent event) {}

}

And in your Configuration Controller or Configuration servlet

String valueReceived = request.getParameter(timeoutValue);
if(valueReceived  != null)
{
    MyHttpSessionListener.globalSessionTimeoutInterval = Integer.parseInt(timeoutValue);
          //Store valueReceived to config.properties file or database
}