cmsxmlentityresolver.java

一个cms内容管理平台

/*
 * File   : $Source: /usr/local/cvs/opencms/src/org/opencms/xml/CmsXmlEntityResolver.java,v $
 * Date   : $Date: 2006/04/28 15:20:52 $
 * Version: $Revision: 1.25 $
 *
 * This library is part of OpenCms -
 * the Open Source Content Mananagement System
 *
 * Copyright (c) 2005 Alkacon Software GmbH (http://www.alkacon.com)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * For further information about Alkacon Software GmbH, please see the
 * company website: http://www.alkacon.com
 *
 * For further information about OpenCms, please see the
 * project website: http://www.opencms.org
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package org.opencms.xml;

import org.opencms.configuration.CmsConfigurationManager;
import org.opencms.file.CmsFile;
import org.opencms.file.CmsObject;
import org.opencms.file.CmsResource;
import org.opencms.main.CmsEvent;
import org.opencms.main.CmsLog;
import org.opencms.main.I_CmsEventListener;
import org.opencms.main.OpenCms;
import org.opencms.util.CmsFileUtil;
import org.opencms.xml.page.CmsXmlPage;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.collections.map.LRUMap;
import org.apache.commons.logging.Log;

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;

/**
 * Resolves XML entities (e.g. external DTDs) in the OpenCms VFS.<p>
 * 
 * Also provides a cache for XML content schema definitions.<p>
 * 
 * @author Alexander Kandzior 
 * 
 * @version $Revision: 1.25 $ 
 * 
 * @since 6.0.0 
 */
public class CmsXmlEntityResolver implements EntityResolver, I_CmsEventListener {

    /** The scheme to identify a file in the OpenCms VFS. */
    public static final String OPENCMS_SCHEME = "opencms://";

    /** The log object for this class. */
    private static final Log LOG = CmsLog.getLog(CmsXmlEntityResolver.class);

    /** A temporary cache for XML content definitions. */
    private static Map m_cacheContentDefinitions;

    /** A permanent cache to avoid multiple readings of often used files from the VFS. */
    private static Map m_cachePermanent;

    /** A temporary cache to avoid multiple readings of often used files from the VFS. */
    private static Map m_cacheTemporary;

    /** The location of the XML page XML schema. */
    private static final String XMLPAGE_OLD_DTD_LOCATION = "org/opencms/xml/page/xmlpage.dtd";

    /** The (old) DTD address of the OpenCms xmlpage (used in 5.3.5). */
    private static final String XMLPAGE_OLD_DTD_SYSTEM_ID_1 = "http://www.opencms.org/dtd/6.0/xmlpage.dtd";

    /** The (old) DTD address of the OpenCms xmlpage (used until 5.3.5). */
    private static final String XMLPAGE_OLD_DTD_SYSTEM_ID_2 = "/system/shared/page.dtd";

    /** The location of the xmlpage XSD. */
    private static final String XMLPAGE_XSD_LOCATION = "org/opencms/xml/page/xmlpage.xsd";

    /** The cms object to use for VFS access (will be initialized with "Guest" permissions). */
    private CmsObject m_cms;

    /**
     * Creates a new XML entity resolver based on the provided CmsObject.<p>
     * 
     * If the provided CmsObject is null, then the OpenCms VFS is not 
     * searched for XML entities, however the internal cache and 
     * other OpenCms internal entities not in the VFS are still resolved.<p> 
     * 
     * @param cms the cms context to use for resolving XML files from the OpenCms VFS
     */
    public CmsXmlEntityResolver(CmsObject cms) {

        initCaches();
        m_cms = cms;
    }

    /**
     * Adds a sytem id URL to to internal permanent cache.<p>
     * 
     * This cache will NOT be cleared automatically.<p>
     * 
     * @param systemId the system id to add
     * @param content the content of the system id
     */
    public static void cacheSystemId(String systemId, byte[] content) {

        initCaches();
        m_cachePermanent.put(systemId, content);
    }

    /**
     * Initialize the OpenCms XML entity resolver.<p>
     * 
     * @param adminCms an initialized OpenCms user context with "Administrator" role permissions
     * @param typeSchemaBytes the base widget type XML schema definitions
     * 
     * @see CmsXmlContentTypeManager#initialize(CmsObject)
     */
    protected static void initialize(CmsObject adminCms, byte[] typeSchemaBytes) {

        // create the resolver to register as event listener
        CmsXmlEntityResolver resolver = new CmsXmlEntityResolver(adminCms);

        // register this object as event listener
        OpenCms.addCmsEventListener(resolver, new int[] {
            I_CmsEventListener.EVENT_CLEAR_CACHES,
            I_CmsEventListener.EVENT_PUBLISH_PROJECT,
            I_CmsEventListener.EVENT_RESOURCE_MODIFIED,
            I_CmsEventListener.EVENT_RESOURCE_DELETED});

        // cache the base widget type XML schema definitions
        cacheSystemId(CmsXmlContentDefinition.XSD_INCLUDE_OPENCMS, typeSchemaBytes);
    }

    /**
     * Initializes the internal caches for permanent and temporary system IDs.<p>
     */
    private static void initCaches() {

        if (m_cacheTemporary == null) {

            LRUMap cacheTemporary = new LRUMap(128);
            m_cacheTemporary = Collections.synchronizedMap(cacheTemporary);

            HashMap cachePermanent = new HashMap(32);
            m_cachePermanent = Collections.synchronizedMap(cachePermanent);

            LRUMap cacheContentDefinitions = new LRUMap(64);
            m_cacheContentDefinitions = Collections.synchronizedMap(cacheContentDefinitions);

            if (OpenCms.getRunLevel() > OpenCms.RUNLEVEL_1_CORE_OBJECT) {
                if ((OpenCms.getMemoryMonitor() != null) && OpenCms.getMemoryMonitor().enabled()) {
                    // map must be of type "LRUMap" so that memory monitor can acecss all information
                    OpenCms.getMemoryMonitor().register(
                        CmsXmlEntityResolver.class.getName() + ".m_cacheTemporary",
                        cacheTemporary);
                    // map must be of type "HashMap" so that memory monitor can acecss all information
                    OpenCms.getMemoryMonitor().register(
                        CmsXmlEntityResolver.class.getName() + ".m_cachePermanent",
                        cachePermanent);
                    // map must be of type "LRUMap" so that memory monitor can acecss all information
                    OpenCms.getMemoryMonitor().register(
                        CmsXmlEntityResolver.class.getName() + ".m_cacheContentDefinitions",
                        cacheContentDefinitions);
                }
            }
        }
    }

    /**
     * Caches an XML content defintion based on the given system id and the online / offline status
     * of this entity resolver instance.<p>
     * 
     * @param systemId the system id to use as cache key
     * @param contentDefinition the content definition to cache
     */
    public void cacheContentDefinition(String systemId, CmsXmlContentDefinition contentDefinition) {

        String cacheKey = getCacheKeyForCurrentProject(systemId);
        m_cacheContentDefinitions.put(cacheKey, contentDefinition);
        if (LOG.isDebugEnabled()) {
            LOG.debug(Messages.get().getBundle().key(Messages.LOG_ER_CACHED_SYSTEM_ID_1, cacheKey));
        }
    }

    /**
     * @see org.opencms.main.I_CmsEventListener#cmsEvent(org.opencms.main.CmsEvent)