| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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.apache.commons.chain2.web; |
| |
| import java.io.IOException; |
| |
| import javax.servlet.ServletConfig; |
| 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.apache.commons.chain2.Catalog; |
| import org.apache.commons.chain2.CatalogFactory; |
| import org.apache.commons.chain2.config.xml.XmlConfigParser; |
| import org.apache.commons.chain2.impl.CatalogBase; |
| import org.apache.commons.chain2.web.servlet.ServletWebContext; |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| /** |
| * <p><code>Servlet</code> that automatically scans chain configuration files |
| * in the current web application at startup time, and exposes the result in a |
| * {@link Catalog} under a specified servlet context attribute. The following |
| * <em>servlet</em> init parameters are utilized:</p> |
| * <ul> |
| * <li><strong>org.apache.commons.chain2.CONFIG_CLASS_RESOURCE</strong> - |
| * comma-delimited list of chain configuration resources to be loaded |
| * via <code>ClassLoader.getResource()</code> calls. If not specified, |
| * no class loader resources will be loaded.</li> |
| * <li><strong>org.apache.commons.chain2.CONFIG_WEB_RESOURCE</strong> - |
| * comma-delimited list of chain configuration webapp resources |
| * to be loaded. If not specified, no web application resources |
| * will be loaded.</li> |
| * <li><strong>org.apache.commons.chain2.CONFIG_ATTR</strong> - |
| * Name of the servlet context attribute under which the |
| * resulting {@link Catalog} will be created or updated. |
| * If not specified, it is expected that parsed resources will |
| * contain <code><catalog></code> elements (which will |
| * cause registration of the created {@link Catalog}s into |
| * the {@link CatalogFactory} for this application, and no |
| * servet context attribute will be created. |
| * <strong>NOTE</strong> - This parameter is deprecated.</p> |
| * <li><strong>org.apache.commons.chain2.RULE_SET</strong> - |
| * Fully qualified class name of a Digester <code>RuleSet</code> |
| * implementation to use for parsing configuration resources (this |
| * class must have a public zero-args constructor). If not defined, |
| * the standard <code>RuleSet</code> implementation will be used.</li> |
| * </ul> |
| * |
| * <p>When a web application that has configured this servlet is |
| * started, it will acquire the {@link Catalog} under the specified servlet |
| * context attribute key, creating a new one if there is none already there. |
| * This {@link Catalog} will then be populated by scanning configuration |
| * resources from the following sources (loaded in this order):</p> |
| * <ul> |
| * <li>Resources loaded from specified resource paths from the |
| * webapp's class loader (via <code>ClassLoader.getResource()</code>).</li> |
| * <li>Resources loaded from specified resource paths in the web application |
| * archive (via <code>ServetContext.getResource()</code>).</li> |
| * </ul> |
| * |
| * <p>If no attribute key is specified, on the other hand, parsed configuration |
| * resources are expected to contain <code><catalog></code> elements, |
| * and the catalogs will be registered with the {@link CatalogFactory} |
| * for this web application.</p> |
| * |
| * <p>This class runs on Servlet 2.2 or later. If you are running on a |
| * Servlet 2.3 or later system, you should also consider using |
| * {@link ChainListener} to initialize your {@link Catalog}. Note that |
| * {@link ChainListener} uses parameters of the same names, but they are |
| * <em>context</em> init parameters instead of <em>servlet</em> init |
| * parameters. Because of this, you can use both facilities in the |
| * same application, if desired.</p> |
| * |
| * @version $Id$ |
| */ |
| public class ChainServlet extends HttpServlet { |
| { |
| CatalogFactory.checkForValidConfigurationModule(); |
| } |
| |
| // ------------------------------------------------------ Manifest Constants |
| |
| /** |
| * |
| */ |
| private static final long serialVersionUID = 20120724L; |
| |
| /** |
| * <p>The name of the context init parameter containing the name of the |
| * servlet context attribute under which our resulting {@link Catalog} |
| * will be stored.</p> |
| */ |
| public static final String CONFIG_ATTR = |
| "org.apache.commons.chain2.CONFIG_ATTR"; |
| |
| /** |
| * <p>The name of the context init parameter containing a comma-delimited |
| * list of class loader resources to be scanned.</p> |
| */ |
| public static final String CONFIG_CLASS_RESOURCE = |
| "org.apache.commons.chain2.CONFIG_CLASS_RESOURCE"; |
| |
| /** |
| * <p>The name of the context init parameter containing a comma-delimited |
| * list of web application resources to be scanned.</p> |
| */ |
| public static final String CONFIG_WEB_RESOURCE = |
| "org.apache.commons.chain2.CONFIG_WEB_RESOURCE"; |
| |
| /** |
| * <p>The name of the context init parameter containing the fully |
| * qualified class name of the <code>RuleSet</code> implementation |
| * for configuring our {@link XmlConfigParser}.</p> |
| */ |
| public static final String RULE_SET = |
| "org.apache.commons.chain2.RULE_SET"; |
| |
| // --------------------------------------------------------- Servlet Methods |
| |
| /** |
| * <p>Clean up after ourselves as this application shuts down.</p> |
| */ |
| @Override |
| public void destroy() { |
| ServletConfig config = getServletConfig(); |
| ServletContext context = getServletContext(); |
| String attr = config.getInitParameter(CONFIG_ATTR); |
| if (attr != null) { |
| context.removeAttribute(attr); |
| } |
| CatalogFactory.clear(); |
| } |
| |
| /** |
| * <p>Create (if necessary) and configure a {@link Catalog} from the |
| * servlet init parameters that have been specified.</p> |
| * |
| * @throws ServletException if the servlet could not be initialized |
| */ |
| @Override |
| public void init() throws ServletException { |
| Log log = LogFactory.getLog(ChainServlet.class); |
| ServletConfig config = getServletConfig(); |
| ServletContext context = getServletContext(); |
| if (log.isInfoEnabled()) { |
| log.info("Initializing chain servlet '" |
| + config.getServletName() + "'"); |
| } |
| |
| // Retrieve servlet init parameters that we need |
| String attr = config.getInitParameter(CONFIG_ATTR); |
| String classResources = |
| context.getInitParameter(CONFIG_CLASS_RESOURCE); |
| String ruleSet = context.getInitParameter(RULE_SET); |
| String webResources = context.getInitParameter(CONFIG_WEB_RESOURCE); |
| |
| // Retrieve or create the Catalog instance we may be updating |
| Catalog<String, Object, ServletWebContext<String, Object>> catalog = null; |
| if (attr != null) { |
| Object catalogRef = context.getAttribute(attr); |
| |
| if (catalogRef == null || !(catalogRef instanceof Catalog)) { |
| catalog = new CatalogBase<String, Object, ServletWebContext<String, Object>>(); |
| } else { |
| catalog = (Catalog<String, Object, ServletWebContext<String, Object>>)catalogRef; |
| } |
| } |
| |
| // Construct the configuration resource parser we will use |
| ClassLoader cl = Thread.currentThread().getContextClassLoader() == null ? |
| this.getClass().getClassLoader() : |
| Thread.currentThread().getContextClassLoader(); |
| |
| XmlConfigParser parser = ruleSet == null ? |
| new XmlConfigParser() : new XmlConfigParser(ruleSet, cl); |
| |
| // Parse the resources specified in our init parameters (if any) |
| if (attr == null) { |
| ChainResources.parseClassResources |
| (classResources, parser); |
| ChainResources.parseWebResources |
| (context, webResources, parser); |
| } else { |
| ChainResources.parseClassResources |
| (classResources, parser); |
| ChainResources.parseWebResources |
| (context, webResources, parser); |
| } |
| |
| // Expose the completed catalog (if requested) |
| if (attr != null) { |
| context.setAttribute(attr, catalog); |
| } |
| } |
| |
| /** |
| * <p>Does nothing; this servlet's only purpose is to initialize a Chain |
| * and store it in the servlet context.</p> |
| * |
| * @param request the request issued by the client |
| * @param response the response to be returned to the cliengt |
| * |
| * @throws javax.servlet.ServletException (this exception is never thrown) |
| * @throws java.io.IOException (this exception is never thrown) |
| */ |
| @Override |
| public void service(HttpServletRequest request, |
| HttpServletResponse response) |
| throws ServletException, IOException { |
| // do nothing |
| } |
| |
| } |
