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package com.sun.appserv.web.taglibs.cache;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
import com.sun.appserv.util.cache.Cache;
import com.sun.appserv.web.cache.CacheManager;
/**
* HttpSessionListener which creates a cache for JSP tag body invocations
* and adds it as a session attribute in response to sessionCreated events,
* and clears the cache in response to sessionDestroyed events.
*/
public class CacheSessionListener implements HttpSessionListener {
/**
* No-arg constructor
*/
public CacheSessionListener() {}
/**
* Receives notification that a session was created, and adds newly
* created cache for JSP tag body invocations as a session attribute.
*
* @param hse the notification event
*/
public void sessionCreated(HttpSessionEvent hse) {
HttpSession session = hse.getSession();
ServletContext context = session.getServletContext();
// Check if a cache manager has already been created and set in the
// context
CacheManager cm = (CacheManager)
context.getAttribute(CacheManager.CACHE_MANAGER_ATTR_NAME);
// Create a new cache manager if one is not present and use it
// to create a new cache
if (cm == null) {
cm = new CacheManager();
}
Cache cache = null;
try {
cache = cm.createCache();
} catch (Exception ex) {}
// Set the cache as a session attribute
if (cache != null) {
session.setAttribute(Constants.JSPTAG_CACHE_KEY, cache);
}
}
/**
* Receives notification that a session is about to be invalidated, and
* clears the session's cache of JSP tag body invocations (if present).
*
* @param hse the notification event
*/
public void sessionDestroyed(HttpSessionEvent hse) {
// Clear the cache
HttpSession session = hse.getSession();
Cache cache = (Cache)session.getAttribute(Constants.JSPTAG_CACHE_KEY);
if (cache != null) {
cache.clear();
}
}
}