/*****************************************************************
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.cayenne.conf;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpSession;
import org.apache.log4j.Logger;
import org.apache.cayenne.access.DataContext;
import org.apache.cayenne.util.ResourceLocator;
import org.apache.cayenne.util.WebApplicationResourceLocator;
/**
* Configuration class that uses ServletContext to locate resources. This class is
* intended for use in J2EE servlet containers. It is compatible with containers following
* servlet specification version 2.2 and newer (e.g. Tomcat can be used starting from
* version 3).
* <p>
* ServletConfiguration resolves configuration file locations relative to the web
* application "WEB-INF" directory, and does not require them to be in the CLASSPATH
* (though CLASSPATH locations such as "/WEB-INF/classes" and "/WEB-INF/lib/some.jar" are
* supported as well). By default search for cayenne.xml is done in /WEB-INF/ folder. To
* specify an arbitrary context path in the web application (e.g. "/WEB-INF/cayenne"), use
* <code>cayenne.configuration.path</code> context parameters in <code>web.xml</code>.
* </p>
*
* @author Andrei Adamchik
* @author Scott Finnerty
* @since 1.2
*/
public class ServletUtil {
private static Logger logObj = Logger.getLogger(ServletUtil.class);
/**
* A name of the web application initialization parameter used to specify extra paths
* where Cayenne XML files might be located. E.g. "/WEB-INF/cayenne".
*/
public static final String CONFIGURATION_PATH_KEY = "cayenne.configuration.path";
/**
* Used by BasicServletConfiguration as a session attribute for DataContext.
*/
public static final String DATA_CONTEXT_KEY = "cayenne.datacontext";
/**
* Creates a new ServletConfiguration and sets is as a Configuration signleton.
*/
public synchronized static Configuration initializeSharedConfiguration(
ServletContext context) {
// check if this web application is already configured
// don't use static getter, since it will do initialization on demand!!!
Configuration oldConfig = Configuration.sharedConfiguration;
if (oldConfig instanceof DefaultConfiguration) {
ResourceLocator locator = ((DefaultConfiguration) oldConfig)
.getResourceLocator();
if (locator instanceof WebApplicationResourceLocator) {
if (((WebApplicationResourceLocator) locator).getServletContext() == context) {
logObj
.info("Configuration is already initialized with this context, reusing.");
return oldConfig;
}
}
}
// create new shared configuration
DefaultConfiguration conf = new DefaultConfiguration(
Configuration.DEFAULT_DOMAIN_FILE,
createLocator(context));
Configuration.initializeSharedConfiguration(conf);
return conf;
}
/**
* A helper method to create default ResourceLocator.
*/
protected static ResourceLocator createLocator(ServletContext context) {
WebApplicationResourceLocator locator = new WebApplicationResourceLocator();
locator.setSkipAbsolutePath(true);
locator.setSkipClasspath(false);
locator.setSkipCurrentDirectory(true);
locator.setSkipHomeDirectory(true);
locator.setServletContext(context);
String configurationPath = context.getInitParameter(CONFIGURATION_PATH_KEY);
if (configurationPath != null && configurationPath.trim().length() > 0) {
locator.addFilesystemPath(configurationPath.trim());
}
return locator;
}
/**
* Returns default Cayenne DataContext associated with the HttpSession, creating it on
* the fly and storing in the session if needed.
*/
public static DataContext getSessionContext(HttpSession session) {
synchronized (session) {
DataContext ctxt = (DataContext) session.getAttribute(DATA_CONTEXT_KEY);
if (ctxt == null) {
ctxt = DataContext.createDataContext();
session.setAttribute(ServletUtil.DATA_CONTEXT_KEY, ctxt);
}
return ctxt;
}
}
}