## org.springframework.web.util
Class HttpSessionMutexListener

    java.lang.Object
      org.springframework.web.util.HttpSessionMutexListener

All Implemented Interfaces:
  EventListener, HttpSessionListener

    public class HttpSessionMutexListener

extends Object
implements HttpSessionListener

Servlet 2.3 HttpSessionListener that automatically exposes the session mutex when an HttpSession gets created. To be registered as a listener in `web.xml`.

The session mutex is guaranteed to be the same object during the entire lifetime of the session, available under the key defined by the `SESSION_MUTEX_ATTRIBUTE` constant. It serves as a safe reference to synchronize on for locking on the current session.

In many cases, the HttpSession reference itself is a safe mutex as well, since it will always be the same object reference for the same active logical session. However, this is not guaranteed across different servlet containers; the only 100% safe way is a session mutex.

Since:
  1.2.7
Author:
  Juergen Hoeller
See Also:
  `WebUtils.SESSION_MUTEX_ATTRIBUTE`, `WebUtils.getSessionMutex(javax.servlet.http.HttpSession)`, `AbstractController.setSynchronizeOnSession(boolean)`

Constructor Summary
`HttpSessionMutexListener()`

Method Summary
`void` `sessionCreated(HttpSessionEvent event)`
`void` `sessionDestroyed(HttpSessionEvent event)`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### HttpSessionMutexListener

    public HttpSessionMutexListener()

Method Detail

### sessionCreated

    public void sessionCreated(HttpSessionEvent event)

  Specified by:
    `sessionCreated` in interface `HttpSessionListener`

### sessionDestroyed

    public void sessionDestroyed(HttpSessionEvent event)

  Specified by:
    `sessionDestroyed` in interface `HttpSessionListener`

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