/*
* Copyright 2007-2008 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.impalaframework.web.helper;
import javax.servlet.ServletContext;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.impalaframework.exception.ConfigurationException;
import org.impalaframework.module.bootstrap.ModuleManagementFacade;
import org.impalaframework.module.holder.ModuleStateChangeListener;
import org.impalaframework.module.holder.ModuleStateChangeNotifier;
import org.impalaframework.module.holder.ModuleStateHolder;
import org.impalaframework.module.modification.ModuleStateChange;
import org.impalaframework.module.modification.Transition;
import org.impalaframework.web.WebConstants;
import org.springframework.beans.BeansException;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.util.Assert;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.servlet.FrameworkServlet;
/**
* Encapsulates mechanism for retrieving module from Impala's context and making it available as the
* Spring context to represent a particular Servlet instance. Supports reloading of the
* backing <code>ApplicationContext</code> through <code>ModuleStateChangeListener</code>
* @author Phil Zoio
*/
public class FrameworkServletContextCreator {
private static final Log logger = LogFactory.getLog(FrameworkServletContextCreator.class);
private static final long serialVersionUID = 1L;
private boolean initialized;
private FrameworkServlet servlet;
public FrameworkServletContextCreator(FrameworkServlet servlet) {
Assert.notNull(servlet);
this.servlet = servlet;
}
public WebApplicationContext createWebApplicationContext() throws BeansException {
// the superclass closes the modules
final ServletContext servletContext = servlet.getServletContext();
ModuleManagementFacade facade = ImpalaServletUtils.getModuleManagementFactory(servletContext);
if (facade == null) {
throw new ConfigurationException("Unable to load " + FrameworkServletContextCreator.class.getName()
+ " as no attribute '" + WebConstants.IMPALA_FACTORY_ATTRIBUTE
+ "' has been set up. Have you set up your Impala ContextLoader correctly?");
}
final String servletName = servlet.getServletName();
ModuleStateHolder moduleStateHolder = facade.getModuleStateHolder();
if (!initialized) {
ModuleStateChangeNotifier moduleStateChangeNotifier = facade.getModuleStateChangeNotifier();
moduleStateChangeNotifier.addListener(new ModuleStateChangeListener() {
public void moduleStateChanged(ModuleStateHolder moduleStateHolder, ModuleStateChange change) {
try {
servlet.init();
}
catch (Exception e) {
logger.error("Unable to reinitialize servlet " + servlet.getServletName(), e);
}
}
public String getModuleName() {
return servletName;
}
public Transition getTransition() {
return Transition.UNLOADED_TO_LOADED;
}
});
this.initialized = true;
}
ConfigurableApplicationContext context = moduleStateHolder.getModule(servletName);
if (context != null) {
if (context instanceof WebApplicationContext) {
return (WebApplicationContext) context;
}
else {
throw new ConfigurationException("Module registered under name of servlet '" + servletName
+ "' needs to be an instance of " + WebApplicationContext.class.getName());
}
}
else {
throw new ConfigurationException("No module registered under the name of servlet '" + servletName + "'");
}
}
}