/*
* 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.spring.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.exception.ExecutionException;
import org.impalaframework.facade.ModuleManagementFacade;
import org.impalaframework.module.spi.Application;
import org.impalaframework.module.spi.ModuleStateChangeListener;
import org.impalaframework.module.spi.ModuleStateChangeNotifier;
import org.impalaframework.module.spi.ModuleStateHolder;
import org.impalaframework.module.spi.Transition;
import org.impalaframework.module.spi.TransitionResult;
import org.impalaframework.spring.module.SpringModuleUtils;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.util.Assert;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.servlet.FrameworkServlet;
/**
* Delegate class responsible for creating {@link WebApplicationContext} on
* behalf of Servlet instance. Used by
* {@link org.impalaframework.web.spring.servlet.ExternalModuleServlet} and
* {@link org.impalaframework.web.spring.integration.ExternalFrameworkIntegrationServlet},
* which are both servlets set up in <i>WEB-INF/web.xml</i>.
*
* This class 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.getModuleManagementFacade(servletContext);
final String servletName = servlet.getServletName();
Application application = facade.getApplicationManager().getCurrentApplication();
ModuleStateHolder moduleStateHolder = application.getModuleStateHolder();
if (!initialized) {
ModuleStateChangeNotifier moduleStateChangeNotifier = facade.getModuleStateChangeNotifier();
ModuleStateChangeListener listener = newModuleStateChangeListener(servletName);
moduleStateChangeNotifier.addListener(listener);
this.initialized = true;
}
ApplicationContext context = SpringModuleUtils.getModuleSpringContext(moduleStateHolder, 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 + "'");
}
}
ModuleStateChangeListener newModuleStateChangeListener(final String servletName) {
ModuleStateChangeListener listener = new ModuleStateChangeListener() {
public void moduleStateChanged(ModuleStateHolder moduleStateHolder, TransitionResult result) {
if (!result.isInError()) {
try {
servlet.init();
}
catch (Exception e) {
throw new ExecutionException("Unable to reinitialize servlet " + servletName, e);
}
} else {
logger.warn("Not attempting to initialize servlet " + servletName + " as module loading failed");
}
}
public String getModuleName() {
return servletName;
}
public String getTransition() {
return Transition.UNLOADED_TO_LOADED;
}
};
return listener;
}
}