/*
* Copyright 2002-2016 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".
Can be used for toolkits that support substitution with system properties
(i.e. System.getProperty values), like log4j's "${key}" syntax within log
file locations.
Note: This listener should be placed before ContextLoaderListener in web.xml, at least when used for log4j. Log4jConfigListener sets the system property implicitly, so there's no need for this listener in addition to it.
WARNING: Some containers, e.g. Tomcat, do NOT keep system properties separate
per web app. You have to use unique "webAppRootKey" context-params per web app
then, to avoid clashes. Other containers like Resin do isolate each web app's
system properties: Here you can use the default key (i.e. no "webAppRootKey"
context-param at all) without worrying.
WARNING: The WAR file containing the web application needs to be expanded
to allow for setting the web app root system property. This is by default not
the case when a WAR file gets deployed to WebLogic, for example. Do not use
this listener in such an environment!
Author: Juergen Hoeller See Also: Since: 18.04.2003
/**
* Listener that sets a system property to the web application root directory.
* The key of the system property can be defined with the "webAppRootKey" init
* parameter at the servlet context level (i.e. context-param in web.xml),
* the default key is "webapp.root".
*
* <p>Can be used for toolkits that support substitution with system properties
* (i.e. System.getProperty values), like log4j's "${key}" syntax within log
* file locations.
*
* <p>Note: This listener should be placed before ContextLoaderListener in {@code web.xml},
* 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 System#getProperty
*/
public class WebAppRootListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent event) {
WebUtils.setWebAppRootSystemProperty(event.getServletContext());
}
@Override
public void contextDestroyed(ServletContextEvent event) {
WebUtils.removeWebAppRootSystemProperty(event.getServletContext());
}
}