Spring Framework example source code file (ContextLoaderServlet.java)

This example Spring Framework source code file (ContextLoaderServlet.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

api, api, attempt, contextloader, contextloader, contextloaderservlet, contextloaderservlet, http, httpservlet, httpservletresponse, io, ioexception, request, response, servlet, servlet, servletexception, string

The Spring Framework ContextLoaderServlet.java source code

/*
 * Copyright 2002-2007 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.springframework.web.context;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Bootstrap servlet to start up Spring's root {@link WebApplicationContext}.
 * Simply delegates to {@link ContextLoader}.
 *
 * <p>This servlet should have a lower load-on-startup value
 * in <code>web.xml than any servlets that access the root web
 * application context.
 *
 * <p>Note that this class has been deprecated for containers implementing
 * Servlet API 2.4 or higher, in favor of {@link ContextLoaderListener}.</i>

 * According to Servlet 2.4, listeners must be initialized before load-on-startup
 * servlets. Many Servlet 2.3 containers already enforce this behavior. If you
 * use such a container, this servlet can be replaced with ContextLoaderListener.
 *
 * <p>Servlet 2.3 containers known to work with bootstrap listeners are:
 * <ul>
 * <li>Apache Tomcat 4.x+
 * <li>Jetty 4.x+
 * <li>Resin 2.1.8+
 * <li>Orion 2.0.2+
 * <li>BEA WebLogic 8.1 SP3
 * </ul>
 * For working with any of them, ContextLoaderListener is recommended.
 *
 * <p>Servlet 2.3 containers known not to work with bootstrap listeners are:
 * <ul>
 * <li>BEA WebLogic up to 8.1 SP2
 * <li>IBM WebSphere 5.x
 * <li>Oracle OC4J 9.0.3
 * </ul>
 * If you happen to work with such a server, this servlet has to be used.
 *
 * <p>So unfortunately, the only context initialization option that is compatible
 * with <i>all Servlet 2.3 containers is this servlet.
 *
 * <p>Note that a startup failure of this servlet will not stop the rest of the
 * web application from starting, in contrast to a listener failure. This can
 * lead to peculiar side effects if other servlets get started that depend on
 * initialization of the root web application context.
 *
 * @author Juergen Hoeller
 * @author Darren Davison
 * @see ContextLoaderListener
 * @see org.springframework.web.util.Log4jConfigServlet
 */
public class ContextLoaderServlet extends HttpServlet {

	private ContextLoader contextLoader;


	/**
	 * Initialize the root web application context.
	 */
	public void init() throws ServletException {
		this.contextLoader = createContextLoader();
		this.contextLoader.initWebApplicationContext(getServletContext());
	}

	/**
	 * Create the ContextLoader to use. Can be overridden in subclasses.
	 * @return the new ContextLoader
	 */
	protected ContextLoader createContextLoader() {
		return new ContextLoader();
	}

	/**
	 * Return the ContextLoader used by this servlet. 
	 * @return the current ContextLoader
	 */
	public ContextLoader getContextLoader() {
		return this.contextLoader;
	}


	/**
	 * Close the root web application context.
	 */
	public void destroy() {
		if (this.contextLoader != null) {
			this.contextLoader.closeWebApplicationContext(getServletContext());
		}
	}


	/**
	 * This should never even be called since no mapping to this servlet should
	 * ever be created in web.xml. That's why a correctly invoked Servlet 2.3
	 * listener is much more appropriate for initialization work ;-)
	 */
	public void service(HttpServletRequest request, HttpServletResponse response) throws IOException {
		getServletContext().log(
				"Attempt to call service method on ContextLoaderServlet as [" +
				request.getRequestURI() + "] was ignored");
		response.sendError(HttpServletResponse.SC_BAD_REQUEST);
	}


	public String getServletInfo() {
		return "ContextLoaderServlet for Servlet API 2.3 " +
		    "(deprecated in favor of ContextLoaderListener for Servlet API 2.4)";
	}

}