containerutil.java

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/*
 * Copyright 2005 Joe Walker
 *
 * 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.directwebremoting.impl;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.StringTokenizer;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.xml.parsers.ParserConfigurationException;

import org.directwebremoting.Container;
import org.directwebremoting.ServerContextFactory.ServerContextBuilder;
import org.directwebremoting.WebContextFactory.WebContextBuilder;
import org.directwebremoting.dwrp.DefaultConverterManager;
import org.directwebremoting.dwrp.HtmlCallMarshaller;
import org.directwebremoting.dwrp.PlainCallMarshaller;
import org.directwebremoting.extend.AccessControl;
import org.directwebremoting.extend.AjaxFilterManager;
import org.directwebremoting.extend.Configurator;
import org.directwebremoting.extend.ConverterManager;
import org.directwebremoting.extend.Creator;
import org.directwebremoting.extend.CreatorManager;
import org.directwebremoting.extend.DebugPageGenerator;
import org.directwebremoting.extend.DwrConstants;
import org.directwebremoting.extend.Handler;
import org.directwebremoting.extend.PageNormalizer;
import org.directwebremoting.extend.Remoter;
import org.directwebremoting.extend.ScriptSessionManager;
import org.directwebremoting.extend.ServerLoadMonitor;
import org.directwebremoting.servlet.AboutHandler;
import org.directwebremoting.servlet.AuthHandler;
import org.directwebremoting.servlet.DwrWebContextFilter;
import org.directwebremoting.servlet.EngineHandler;
import org.directwebremoting.servlet.HtmlCallHandler;
import org.directwebremoting.servlet.HtmlPollHandler;
import org.directwebremoting.servlet.IndexHandler;
import org.directwebremoting.servlet.InterfaceHandler;
import org.directwebremoting.servlet.PathConstants;
import org.directwebremoting.servlet.PlainCallHandler;
import org.directwebremoting.servlet.PlainPollHandler;
import org.directwebremoting.servlet.TestHandler;
import org.directwebremoting.servlet.UrlProcessor;
import org.directwebremoting.servlet.UtilHandler;
import org.directwebremoting.servlet.WebworkUtilHandler;
import org.directwebremoting.util.LocalUtil;
import org.directwebremoting.util.Logger;
import org.xml.sax.SAXException;

/**
 * An abstraction of all the common servlet operations that are required to host
 * a DWR service that depends on the servlet spec.
 * It would be good to have a base class for all servlet operations, however
 * lack of MI prevents us from doing this.
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class ContainerUtil
{
    /**
     * Create a {@link DefaultContainer}, allowing users to upgrade to a child
     * of DefaultContainer using an {@link ServletConfig} init parameter of
     * <code>org.directwebremoting.Container</code>. Note that while the
     * parameter name is the classname of {@link Container}, currently the only
     * this can only be used to create children that inherit from
     * {@link DefaultContainer}. This restriction may be relaxed in the future.
     * Unlike {@link #setupDefaultContainer(DefaultContainer, ServletConfig)},
     * this method does not call any setup methods.
     * @param servletConfig The source of init parameters
     * @return An unsetup implementaion of DefaultContainer
     * @throws ServletException If the specified class could not be found
     * @see ServletConfig#getInitParameter(String)
     */
    public static DefaultContainer createDefaultContainer(ServletConfig servletConfig) throws ServletException
    {
        try
        {
            String typeName = servletConfig.getInitParameter(Container.class.getName());
            if (typeName == null)
            {
                return new DefaultContainer();
            }

            log.debug("Using alternate Container implementation: " + typeName);
            Class type = LocalUtil.classForName(typeName);
            return (DefaultContainer) type.newInstance();
        }
        catch (Exception ex)
        {
            throw new ServletException(ex);
        }
    }

    /**
     * Setup a {@link DefaultContainer}.
     * Using {@link #createDefaultContainer(ServletConfig)} followed by
     * {@link #setupFromServletConfig(DefaultContainer, ServletConfig)} before
     * calling {@link DefaultContainer#setupFinished()}.
     * @param container The container to configure
     * @param servletConfig The source of init parameters
     * @throws InstantiationException If we can't instantiate a bean
     * @throws IllegalAccessException If we have access problems creating a bean
     */
    public static void setupDefaultContainer(DefaultContainer container, ServletConfig servletConfig) throws InstantiationException, IllegalAccessException
    {
        setupDefaults(container, servletConfig);
        setupFromServletConfig(container, servletConfig);
        container.setupFinished();
    }

    /**
     * Take a DefaultContainer and setup the default beans
     * @param container The container to configure
     * @param servletConfig The source of init parameters
     * @throws InstantiationException If we can't instantiate a bean
     * @throws IllegalAccessException If we have access problems creating a bean
     */
    public static void setupDefaults(DefaultContainer container, ServletConfig servletConfig) throws InstantiationException, IllegalAccessException
    {
        container.addParameter(AccessControl.class.getName(), DefaultAccessControl.class.getName());
        container.addParameter(ConverterManager.class.getName(), DefaultConverterManager.class.getName());
        container.addParameter(CreatorManager.class.getName(), DefaultCreatorManager.class.getName());
        container.addParameter(UrlProcessor.class.getName(), UrlProcessor.class.getName());
        container.addParameter(WebContextBuilder.class.getName(), DefaultWebContextBuilder.class.getName());
        container.addParameter(ServerContextBuilder.class.getName(), DefaultServerContextBuilder.class.getName());
        container.addParameter(AjaxFilterManager.class.getName(), DefaultAjaxFilterManager.class.getName());
        container.addParameter(Remoter.class.getName(), DefaultRemoter.class.getName());
        container.addParameter(DebugPageGenerator.class.getName(), DefaultDebugPageGenerator.class.getName());
        container.addParameter(PlainCallMarshaller.class.getName(), PlainCallMarshaller.class.getName());
        container.addParameter(HtmlCallMarshaller.class.getName(), HtmlCallMarshaller.class.getName());
        container.addParameter(PlainPollHandler.class.getName(), PlainPollHandler.class.getName());
        container.addParameter(HtmlPollHandler.class.getName(), HtmlPollHandler.class.getName());
        container.addParameter(ScriptSessionManager.class.getName(), DefaultScriptSessionManager.class.getName());
        container.addParameter(PageNormalizer.class.getName(), DefaultPageNormalizer.class.getName());

        if (servletConfig.getServletContext().getServerInfo().startsWith("jetty-6"))
        {
            container.addParameter(ServerLoadMonitor.class.getName(), ThreadDroppingServerLoadMonitor.class.getName());
        }
        else
        {
            container.addParameter(ServerLoadMonitor.class.getName(), DefaultServerLoadMonitor.class.getName());
        }

        // Mapping handlers to URLs
        createUrlMapping(container, "/index.html", "indexHandlerUrl", IndexHandler.class);
        createUrlMapping(container, "/engine.js", "engineHandlerUrl", EngineHandler.class);
        createUrlMapping(container, "/util.js", "utilHandlerUrl", UtilHandler.class);
        createUrlMapping(container, "/auth.js", "authHandlerUrl", AuthHandler.class);
        createUrlMapping(container, "/webwork/DWRActionUtil.js", "webworkUtilHandlerUrl", WebworkUtilHandler.class);
        createUrlMapping(container, "/about", "aboutHandlerUrl", AboutHandler.class);
        createUrlMapping(container, "/test/", "testHandlerUrl", TestHandler.class);
        createUrlMapping(container, "/interface/", "interfaceHandlerUrl", InterfaceHandler.class);

        // The Poll and Call URLs can not be changed easily because they are
        // referenced from engine.js. Maybe one day this would be a good
        // extension
        createUrlMapping(container, "/call/plaincall/", "plainCallHandlerUrl", PlainCallHandler.class);
        createUrlMapping(container, "/call/plainpoll/", "plainPollHandlerUrl", PlainPollHandler.class);
        createUrlMapping(container, "/call/htmlcall/", "htmlCallHandlerUrl", HtmlCallHandler.class);
        createUrlMapping(container, "/call/htmlpoll/", "htmlPollHandlerUrl", HtmlPollHandler.class);

        container.addParameter("maxWaitAfterWrite", "500");
    }

    /**
     * Creates entries in the {@link Container} so 2 lookups are possible.
     * <ul>
     * <li>You can find a {@link Handler} for a URL. Used by {@link UrlProcessor}
     * <li>You can inject (or lookup) the URL assigned to a {@link Handler}
     * </ul>
     * @param container The container to create the entries in
     * @param url The URL of the new {@link Handler}
     * @param propertyName The property name (for injection and lookup)
     * @param handler The class of Handler
     * @throws InstantiationException From {@link DefaultContainer#addParameter(Object, Object)}
     * @throws IllegalAccessException From {@link DefaultContainer#addParameter(Object, Object)}
     */
    public static void createUrlMapping(DefaultContainer container, String url, String propertyName, Class handler) throws InstantiationException, IllegalAccessException
    {
        container.addParameter(PathConstants.URL_PREFIX + url, handler.getName());
        container.addParameter(propertyName, url);
    }

    /**
     * Take a DefaultContainer and setup the default beans
     * @param container The container to configure
     * @param servletConfig The servlet configuration (null to ignore)
     * @throws InstantiationException If we can't instantiate a bean
     * @throws IllegalAccessException If we have access problems creating a bean
     */
    public static void setupFromServletConfig(DefaultContainer container, ServletConfig servletConfig) throws InstantiationException, IllegalAccessException
    {
        Enumeration en = servletConfig.getInitParameterNames();
        while (en.hasMoreElements())
        {
            String name = (String) en.nextElement();
            String value = servletConfig.getInitParameter(name);
            container.addParameter(name, value);
        }
    }

    /**
     * Make some changes to the ServletContext so {@link DwrWebContextFilter}
     * can find the Container etc.
     * @param context The servlet context
     * @param config The servlet configuration
     * @param container The container to save in the ServletContext
     * @param webContextBuilder The WebContextBuilder to save
     * @param servlet The Servlet to save
     */
    public static void prepareForWebContextFilter(ServletContext context, ServletConfig config, Container container, WebContextBuilder webContextBuilder, HttpServlet servlet)
    {
        context.setAttribute(Container.class.getName(), container);
        context.setAttribute(WebContextBuilder.class.getName(), webContextBuilder);
        context.setAttribute(ServletConfig.class.getName(), config);
        context.setAttribute(HttpServlet.class.getName(), servlet);
    }

    /**
     * Configure using the system dwr.xml from within the JAR file.
     * @param container The container to configure
     * @throws ParserConfigurationException If the config file parse fails
     * @throws IOException If the config file read fails
     * @throws SAXException If the config file parse fails
     */
    public static void configureFromSystemDwrXml(Container container) throws IOException, ParserConfigurationException, SAXException
    {
        DwrXmlConfigurator system = new DwrXmlConfigurator();
        system.setClassResourceName(DwrConstants.FILE_DWR_XML);
        system.configure(container);
    }

    /**
     * Configure using the users dwr.xml that sits next in WEB-INF
     * @param container The container to configure
     * @throws ParserConfigurationException If the config file parse fails
     * @throws IOException If the config file read fails
     * @throws SAXException If the config file parse fails
     */
    public static void configureFromDefaultDwrXml(Container container) throws IOException, ParserConfigurationException, SAXException
    {
        DwrXmlConfigurator local = new DwrXmlConfigurator();
        local.setServletResourceName(DwrConstants.DEFAULT_DWR_XML);
        local.configure(container);
    }

    /**
     * Add configurators from init params to the end of the list of
     * configurators.
     * @param container The container to configure
     * @param servletConfig The source of init parameters
     * @return true if any Configurators were read
     * @throws SAXException If the config file parse fails
     * @throws ParserConfigurationException If the config file parse fails
     * @throws IOException If the config file read fails
     */
    public static boolean configureFromInitParams(Container container, ServletConfig servletConfig) throws IOException, ParserConfigurationException, SAXException
    {
        Enumeration en = servletConfig.getInitParameterNames();
        boolean foundConfig = false;
        while (en.hasMoreElements())
        {
            String name = (String) en.nextElement();
            String value = servletConfig.getInitParameter(name);

            // if the init param starts with "config" then try to load it
            if (name.startsWith(INIT_CONFIG))
            {
                foundConfig = true;

                StringTokenizer st = new StringTokenizer(value, "\n,");
                while (st.hasMoreTokens())
                {
                    String fileName = st.nextToken().trim();
                    DwrXmlConfigurator local = new DwrXmlConfigurator();
                    local.setServletResourceName(fileName);
                    local.configure(container);
                }
            }
            else if (name.equals(INIT_CUSTOM_CONFIGURATOR))
            {