facesdtdresolver.java

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/*
 * Copyright 2002-2004 the original author or authors.
 *
 * 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 de.mindmatters.faces;

import java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * EntityResolver implementation for the JSF 1.0 and JSF 1.1 DTD, to load the
 * DTD from the jsf-spring class path (or JAR file).
 * 
 * <p>
 * Fetches "web-facesconfig_1_0.dtd" or "web-facesconfig_1_0.dtd" from the class
 * path resource "/de/mindmatters/faces/web-facesconfig_1_0.dtd" or
 * "/de/mindmatters/faces/web-facesconfig_1_1.dtd", no matter whether specified
 * as some local URL that includes "web-facesconfig" in the DTD name or as
 * "http://java.sun.com/dtd/web-facesconfig_1_0.dtd" and
 * "http://java.sun.com/dtd/web-facesconfig_1_1.dtd" respectively.
 * </p>
 * 
 * @author Andreas Kuhrwahl
 */
public final class FacesDtdResolver implements EntityResolver {

    /**
     * The name prefix of the faces dtds (used for loading dtds form class
     * path).
     */
    private static final String DTD_NAME = "web-facesconfig";

    /** For logging. */
    protected final Log logger = LogFactory.getLog(getClass());

    /**
     * {@inheritDoc}
     */
    public InputSource resolveEntity(final String publicId,
            final String systemId) throws SAXException, IOException {
        if (logger.isDebugEnabled()) {
            logger.debug("Trying to resolve XML entity with public ID ["
                    + publicId + "] and system ID [" + systemId + "]");
        }
        InputSource source = null;
        if (systemId != null
                && systemId.indexOf(DTD_NAME) > systemId.lastIndexOf("/")) {
            final String dtdFile = systemId.substring(systemId
                    .indexOf(DTD_NAME));
            if (logger.isDebugEnabled()) {
                logger.debug("Trying to locate [" + dtdFile
                        + "] in jsf-spring jar");
            }
            try {
                final Resource resource = new ClassPathResource(dtdFile,
                        getClass());
                source = new InputSource(resource.getInputStream());
                source.setPublicId(publicId);
                source.setSystemId(systemId);
                if (logger.isDebugEnabled()) {
                    logger.debug("Found faces DTD [" + systemId
                            + "] in classpath");
                }
            } catch (IOException ex) {
                if (logger.isDebugEnabled()) {
                    logger.debug("Could not resolve faces DTD [" + systemId
                            + "]: not found in class path", ex);
                }
            }
        }
        return source;
    }

}