filterdispatcher.java

FilterDispatcher源码,些源码是struts2的核心源码.

/*
 * $Id: FilterDispatcher.java 530439 2007-04-19 15:00:20Z hermanns $
 *
 * 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.struts2.dispatcher;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts2.RequestUtils;
import org.apache.struts2.StrutsConstants;
import org.apache.struts2.StrutsStatics;
import org.apache.struts2.dispatcher.mapper.ActionMapper;
import org.apache.struts2.dispatcher.mapper.ActionMapping;

import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.util.ClassLoaderUtil;
import com.opensymphony.xwork2.util.profiling.UtilTimerStack;
import com.opensymphony.xwork2.ActionContext;

/**
 * Master filter for Struts that handles four distinct
 * responsibilities:
 *
 * <ul>
 *
 * <li>Executing actions</li>
 *
 * <li>Cleaning up the {@link ActionContext} (see note)</li>
 *
 * <li>Serving static content</li>
 *
 * <li>Kicking off XWork's interceptor chain for the request lifecycle</li>
 *
 * </ul>
 *
 * <p/> <b>IMPORTANT</b>: this filter must be mapped to all requests. Unless you know exactly what you are doing, always
 * map to this URL pattern: /*
 *
 * <p/> <b>Executing actions</b>
 *
 * <p/> This filter executes actions by consulting the {@link ActionMapper} and determining if the requested URL should
 * invoke an action. If the mapper indicates it should, <b>the rest of the filter chain is stopped</b> and the action is
 * invoked. This is important, as it means that filters like the SiteMesh filter must be placed <b>before</b> this
 * filter or they will not be able to decorate the output of actions.
 *
 * <p/> <b>Cleaning up the {@link ActionContext}</b>
 *
 * <p/> This filter will also automatically clean up the {@link ActionContext} for you, ensuring that no memory leaks
 * take place. However, this can sometimes cause problems integrating with other products like SiteMesh. See {@link
 * ActionContextCleanUp} for more information on how to deal with this.
 *
 * <p/> <b>Serving static content</b>
 *
 * <p/> This filter also serves common static content needed when using various parts of Struts, such as JavaScript
 * files, CSS files, etc. It works by looking for requests to /struts/*, and then mapping the value after "/struts/"
 * to common packages in Struts and, optionally, in your class path. By default, the following packages are
 * automatically searched:
 *
 * <ul>
 *
 * <li>org.apache.struts2.static</li>
 *
 * <li>template</li>
 *
 * </ul>
 *
 * <p/> This means that you can simply request /struts/xhtml/styles.css and the XHTML UI theme's default stylesheet
 * will be returned. Likewise, many of the AJAX UI components require various JavaScript files, which are found in the
 * org.apache.struts2.static package. If you wish to add additional packages to be searched, you can add a comma
 * separated (space, tab and new line will do as well) list in the filter init parameter named "packages". <b>Be
 * careful</b>, however, to expose any packages that may have sensitive information, such as properties file with
 * database access credentials.
 *
 * <p/>
 * 
 * <p>
 * 
 * This filter supports the following init-params:
 * <!-- START SNIPPET: params -->
 *
 * <ul>
 *
 * <li><b>config</b> - a comma-delimited list of XML configuration files to load.</li>
 *
 * <li><b>actionPackages</b> - a comma-delimited list of Java packages to scan for Actions.</li>
 *
 * <li><b>configProviders</b> - a comma-delimited list of Java classes that implement the 
 * {@link com.opensymphony.xwork2.config.ConfigurationProvider} interface that should be used for building the {@link com.opensymphony.xwork2.config.Configuration}.</li>
 * 
 * <li><b>*</b> - any other parameters are treated as framework constants.</li>
 * 
 * </ul>
 *
 * <!-- END SNIPPET: params -->
 * 
 * </p>
 *
 * To use a custom {@link Dispatcher}, the <code>createDispatcher()</code> method could be overriden by
 * the subclass.
 *
 * @see ActionMapper
 * @see ActionContextCleanUp
 *
 * @version $Date: 2007-04-19 17:00:20 +0200 (Do, 19 Apr 2007) $ $Id: FilterDispatcher.java 530439 2007-04-19 15:00:20Z hermanns $
 */
public class FilterDispatcher implements StrutsStatics, Filter {

    /**
     * Provide a logging instance.
     */
    private static final Log LOG = LogFactory.getLog(FilterDispatcher.class);

    /**
     * Store set of path prefixes to use with static resources.
     */
    private String[] pathPrefixes;

    /**
     * Provide a formatted date for setting heading information when caching static content.
     */
    private final Calendar lastModifiedCal = Calendar.getInstance();

    /**
     * Store state of StrutsConstants.STRUTS_SERVE_STATIC_CONTENT setting.
     */
    private static boolean serveStatic;

    /**
     * Store state of StrutsConstants.STRUTS_SERVE_STATIC_BROWSER_CACHE setting.
     */
    private static boolean serveStaticBrowserCache;

    /**
     * Store state of StrutsConstants.STRUTS_I18N_ENCODING setting.
     */
    private static String encoding;

    /**
     * Provide ActionMapper instance, set by injection.
     */
    private static ActionMapper actionMapper;

    /**
     * Provide FilterConfig instance, set on init.
     */
    private FilterConfig filterConfig;

    /**
     * Expose Dispatcher instance to subclass.
     */
    protected Dispatcher dispatcher;

    /**
     * Initializes the filter by creating a default dispatcher
     * and setting the default packages for static resources.
     *
     * @param filterConfig The filter configuration
     */
    public void init(FilterConfig filterConfig) throws ServletException {
    	 this.filterConfig = filterConfig;
    	 
        dispatcher = createDispatcher(filterConfig);
        dispatcher.init();
       
        String param = filterConfig.getInitParameter("packages");
        String packages = "org.apache.struts2.static template org.apache.struts2.interceptor.debugging";
        if (param != null) {
            packages = param + " " + packages;
        }
        this.pathPrefixes = parse(packages);
    }

    /**
     * Calls dispatcher.cleanup,
     * which in turn releases local threads and destroys any DispatchListeners.
     *
     * @see javax.servlet.Filter#destroy()
     */
    public void destroy() {
        if (dispatcher == null) {
            LOG.warn("something is seriously wrong, Dispatcher is not initialized (null) ");
        } else {
            dispatcher.cleanup();
        }
    }
    
    /**
     * Create a default {@link Dispatcher} that subclasses can override
     * with a custom Dispatcher, if needed.
     *
     * @param filterConfig Our FilterConfig
     * @return Initialized Dispatcher 
     */
    protected Dispatcher createDispatcher(FilterConfig filterConfig) {
        Map<String,String> params = new HashMap<String,String>();
        for (Enumeration e = filterConfig.getInitParameterNames(); e.hasMoreElements(); ) {
            String name = (String) e.nextElement();
            String value = filterConfig.getInitParameter(name);
            params.put(name, value);
        }
        return new Dispatcher(filterConfig.getServletContext(), params);
    }

    /**
     * Modify state of StrutsConstants.STRUTS_SERVE_STATIC_CONTENT setting.
     * @param val New setting
     */
    @Inject(StrutsConstants.STRUTS_SERVE_STATIC_CONTENT)
    public static void setServeStaticContent(String val) {
        serveStatic = "true".equals(val);
    }
    
    /**
     * Modify state of StrutsConstants.STRUTS_SERVE_STATIC_BROWSER_CACHE setting.
     * @param val New setting
     */
    @Inject(StrutsConstants.STRUTS_SERVE_STATIC_BROWSER_CACHE)
    public static void setServeStaticBrowserCache(String val) {
        serveStaticBrowserCache = "true".equals(val);
    }
    
    /**
     * Modify state of StrutsConstants.STRUTS_I18N_ENCODING setting.
     * @param val New setting
     */
    @Inject(StrutsConstants.STRUTS_I18N_ENCODING)
    public static void setEncoding(String val) {
        encoding = val;
    }
    
    /**
     * Modify ActionMapper instance.
     * @param mapper New instance
     */
    @Inject
    public static void setActionMapper(ActionMapper mapper) {
        actionMapper = mapper;
    }
    
    /**
     * Provide a workaround for some versions of WebLogic.
     * <p/>
     * Servlet 2.3 specifies that the servlet context can be retrieved from the session. Unfortunately, some versions of
     * WebLogic can only retrieve the servlet context from the filter config. Hence, this method enables subclasses to