/*
* 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.integration;
import java.io.IOException;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.impalaframework.web.helper.WebServletUtils;
import org.impalaframework.web.servlet.invoker.ThreadContextClassLoaderHttpServiceInvoker;
import org.impalaframework.web.spring.helper.ImpalaServletUtils;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.servlet.HttpServletBean;
/**
* <p>
* Servlet which is design to integrate with web frameworks other than Spring
* MVC. Unlike <code>BaseImpalaServlet</code> it does not need a read-write
* lock to synchronize updates to the <code>ApplicationContext</code> because
* it shares the application context's life cycle. In it's <code>service</code>
* method, it then passes control to the the wired in
* <code>delegateServlet</code> instance, which itself needs to be set up
* using <code>ServletFactoryBean</code>.
* <p>
* In order to set up <code>InternalFrameworkIntegrationServlet</code> you
* don't need an entry in <code>web.xml</code>. Instead, it is automatically
* published to the <code>ServletContext</code> using a name based on the
* wired in servletName, and found using a <code>ModuleProxyServlet</code>
* instance registered in <code>web.xml</code>. This allows you to add and
* remove modules as you please without having to modify web.xml (which would
* require the entire web application to reload). To configure
* <code>InternalFrameworkIntegrationServlet</code> you will need to use
* <code>InternalFrameworkIntegrationServletFactoryBean</code>
*
* @see ModuleProxyServlet
* @see InternalFrameworkIntegrationServletFactoryBean
* @author Phil Zoio
*/
public class InternalFrameworkIntegrationServlet extends HttpServletBean implements ApplicationContextAware {
private static final long serialVersionUID = 1L;
private WebApplicationContext applicationContext;
private HttpServlet delegateServlet;
/**
* Determine whether to set the context class loader. This almost certainly
* need to be true. Frameworks such as Struts which dynamically instantiate
* classes typically use <code>Thread.currentThread().getContextClassLoader()</code> to
* retrieve the class loader with which to instantiate classes. This needs to be set correctly to the
* class loader of the current module's application context to ensure that resource contained within the module
* (e.g. Struts action and form classes) can be found using the current thread's context class loader.
*/
private boolean setContextClassLoader = true;
private ClassLoader currentClassLoader;
private ThreadContextClassLoaderHttpServiceInvoker invoker;
public InternalFrameworkIntegrationServlet() {
super();
}
@Override
public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ClassLoader moduleClassLoader = applicationContext.getClassLoader();
if (this.invoker == null || this.currentClassLoader != moduleClassLoader) {
this.invoker = new ThreadContextClassLoaderHttpServiceInvoker(delegateServlet, setContextClassLoader, moduleClassLoader);
this.currentClassLoader = moduleClassLoader;
}
this.invoker.invoke(request, response, null);
}
@Override
protected void initServletBean() throws ServletException {
final ServletContext servletContext = getServletContext();
final String servletName = getServletName();
WebServletUtils.publishServlet(servletContext, servletName, this);
ImpalaServletUtils.publishRootModuleContext(servletContext, servletName, applicationContext);
}
@Override
public void destroy() {
final ServletContext servletContext = getServletContext();
final String servletName = getServletName();
WebServletUtils.unpublishServlet(servletContext, servletName);
ImpalaServletUtils.unpublishRootModuleContext(servletContext, servletName);
super.destroy();
}
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = ImpalaServletUtils.checkIsWebApplicationContext(getServletName(), applicationContext);
}
/* ************************ injected setters ************************** */
public void setDelegateServlet(HttpServlet delegateServlet) {
this.delegateServlet = delegateServlet;
}
public void setSetContextClassLoader(boolean setContextClassLoader) {
this.setContextClassLoader = setContextClassLoader;
}
}