Just realized that I didn't include the servlet configuration section into the javadoc. Please use the attached source file instead.
/* * Copyright (C) The Apache Software Foundation. All rights reserved. * * This software is published under the terms of the Apache Software License * version 1.1, a copy of which has been included with this distribution in * the LICENSE file. */ package org.apache.avalon.excalibur.servlet;
import java.io.InputStream; import java.io.IOException; import javax.servlet.GenericServlet; import javax.servlet.ServletConfig; import javax.servlet.ServletContext; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.ServletException; import javax.servlet.UnavailableException; import org.xml.sax.SAXException; import org.apache.log.Hierarchy; import org.apache.avalon.framework.component.ComponentManager; import org.apache.avalon.framework.configuration.ConfigurationException; import org.apache.avalon.framework.configuration.DefaultConfigurationBuilder; import org.apache.avalon.framework.configuration.Configuration; import org.apache.avalon.framework.context.DefaultContext; import org.apache.avalon.excalibur.component.ExcaliburComponentManager; import org.apache.avalon.excalibur.component.DefaultRoleManager; import org.apache.avalon.excalibur.component.RoleManager; /** * Initializes servlet component manager. Puts it into the * servlet context. Typical usage of the ComponentManager from a JSP * page is: * <pre> * <%@ page import="org.apache.avalon.framework.component.ComponentManager" %> * <%@ page import="org.apache.avalon.excalibur.servlet.ComponentManagerCreator" %> * <%@ page import="com.mycompany.MyComponent" %> * ComponentManager cm = (ComponentManager) * getServletConfig().getServletContext().getAttribute(ComponentManagerCreator.COMPONENT_MANAGER); * MyComponent myC = (MyComponent) cm.lookup(MyComponent.ROLE); * message = myC.getMessage(); * cm.release(myC); * </pre> * Configures itself from servlet parameters. Here's what a typical section in * web.xml should look like: * <pre> * <servlet> * <servlet-name>ComponentManagerCreator</servlet-name> * <display-name>ComponentManagerCreator</display-name> * <description>Creates component manager, does not service requests.</description> * <servlet-class>org.apache.avalon.excalibur.servlet.ComponentManagerCreator</servlet-class> * * <!-- * This parameter points to the main configuration file. * Note that the path is specified in absolute notation but it will be * resolved relative to the servlets webapp context path * --> * <init-param> * <param-name>configuration</param-name> * <param-value>/WEB-INF/components.xml</param-value> * </init-param> * <!-- Roles file supplements configuration file to make the latter * more readable. Most likely you don't want to change the roles * file --> * <init-param> * <param-name>roles</param-name> * <param-value>/WEB-INF/roles.xml</param-value> * </init-param> * <load-on-startup>1</load-on-startup> * </servlet> * </pre> * @author Gregory Steuck mailto:[EMAIL PROTECTED] */ public class ComponentManagerCreator extends GenericServlet { /** * Name of the servlet context attribute that contains our * component manager. */ public static final String COMPONENT_MANAGER = "org.apache.avalon.excalibur.servlet.ComponentManager"; /** * Builds the component manager, stores it as an attribute of the * ServletContext. */ public void init(ServletConfig config) throws ServletException { super.init(config); try { InputStream roleStream = streamFromParameter(config, "roles"); InputStream configStream = streamFromParameter(config, "configuration"); ServletContext ctx = getServletContext(); ctx.setAttribute(COMPONENT_MANAGER, buildComponentManager(configStream, roleStream)); configStream.close(); roleStream.close(); } catch (IOException e) { abort(e); } catch (SAXException e) { abort(e); } catch (ConfigurationException e) { abort(e); } } /** * Does not process any requests, complains if attempted. Since * it is not mapped to URLs this method should never be called. */ public void service(ServletRequest req, ServletResponse res) throws UnavailableException { abort(getClass().getName() + " doesn't service requests"); } /** * Removes the component manager from the servlet context. * Hardly ever called, but is here for consistency. */ public void destroy() { log(getClass().getName() + " destroyed, removing component manager"); ServletContext ctx = getServletContext(); ExcaliburComponentManager cm = (ExcaliburComponentManager) ctx.getAttribute(COMPONENT_MANAGER); ctx.removeAttribute(COMPONENT_MANAGER); cm.dispose(); } /** * Creates Avalon component manager from the passed config stream * and role config stream. * @param config input stream containing components definitions * @param roles input stream with role definitions */ private ComponentManager buildComponentManager(InputStream configStream, InputStream roleStream) throws IOException, SAXException, ConfigurationException { DefaultConfigurationBuilder builder = new DefaultConfigurationBuilder(); Configuration roleConfig = builder.build(roleStream); DefaultRoleManager roles = new DefaultRoleManager(); roles.setLogger(Hierarchy.getDefaultHierarchy().getLoggerFor("document.roles")); roles.configure(roleConfig); Configuration systemConf = builder.build(configStream); ExcaliburComponentManager manager = new ExcaliburComponentManager(); manager.setLogger(Hierarchy.getDefaultHierarchy().getLoggerFor("bp")); manager.contextualize(new DefaultContext()); manager.setRoleManager(roles); manager.configure(systemConf); manager.initialize(); return manager; } /** * Logs the error message and makes servlet unavailable * by throwing UnavailableException. * * @param msg reason for failure */ private void abort(String msg) throws UnavailableException { log(msg); throw new UnavailableException(msg); } /** * Logs passed exception and makes servlet unavailable * by throwing UnavailableException. * @param e exception that caused the original failure */ private void abort(Exception e) throws UnavailableException { log("", e); throw new UnavailableException(e.getMessage()); } /** * Finds the value for given key in the servlet init parameters, * treats it as a file name, opens a resource stream with this * name. * @param resourceName key into init parameters * @param config connection to the world * @return opened resorce stream * @throws ServletException if init parameter does not exist, or resource can't be opened */ private InputStream streamFromParameter(ServletConfig config, String resourceName) throws ServletException { String configFileName = config.getInitParameter(resourceName); if (configFileName == null) { abort(resourceName + " parameter must be provided"); } ServletContext ctx = config.getServletContext(); log("Attempting to use file " + configFileName); InputStream result = ctx.getResourceAsStream(configFileName); if (result == null) { abort("Resource '" + configFileName + "' is not available."); } return result; } }
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