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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).
 * 

* 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 * cayenne.configuration.path context parameters in web.xml. *

* * @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; } } }




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