/*
* Copyright 2002-2008 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.util;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
/**
* Listener that sets a system property to the web application root directory.
* The key of the system property can be defined with the "webAppRootKey" init
* parameter at the servlet context level (i.e. context-param in web.xml),
* the default key is "webapp.root".
*
* <p>Can be used for toolkits that support substition with system properties
* (i.e. System.getProperty values), like log4j's "${key}" syntax within log
* file locations.
*
* <p>Note: This listener should be placed before ContextLoaderListener in <code>web.xml</code>,
* at least when used for log4j. Log4jConfigListener sets the system property
* implicitly, so there's no need for this listener in addition to it.
*
* <p><b>WARNING</b>: Some containers, e.g. Tomcat, do NOT keep system properties separate
* per web app. You have to use unique "webAppRootKey" context-params per web app
* then, to avoid clashes. Other containers like Resin do isolate each web app's
* system properties: Here you can use the default key (i.e. no "webAppRootKey"
* context-param at all) without worrying.
*
* <p><b>WARNING</b>: The WAR file containing the web application needs to be expanded
* to allow for setting the web app root system property. This is by default not
* the case when a WAR file gets deployed to WebLogic, for example. Do not use
* this listener in such an environment!
*
* @author Juergen Hoeller
* @since 18.04.2003
* @see WebUtils#setWebAppRootSystemProperty
* @see Log4jConfigListener
* @see java.lang.System#getProperty
*/
public class WebAppRootListener implements ServletContextListener {
public void contextInitialized(ServletContextEvent event) {
WebUtils.setWebAppRootSystemProperty(event.getServletContext());
}
public void contextDestroyed(ServletContextEvent event) {
WebUtils.removeWebAppRootSystemProperty(event.getServletContext());
}
}
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