org.data.support.beans.factory.xml.QueryDTDResolver.java Source code

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Here is the source code for org.data.support.beans.factory.xml.QueryDTDResolver.java

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/*
 * Copyright 2013 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 org.data.support.beans.factory.xml;

import java.io.IOException;
import java.util.Arrays;

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 queries DTD,
 * to load the DTD from classpath.
 *
 * <p>Fetches "*.dtd" from the class path resource
 * 
 * @author chen
 * @created Dec 30, 2013
 * @since 2013
 */
public class QueryDTDResolver implements EntityResolver {

    private static final String DTD_EXTENSION = ".dtd";

    private static final String[] DTD_NAMES = { "query-definitions" };

    private static final Log logger = LogFactory.getLog(QueryDTDResolver.class);

    @Override
    public InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException {
        if (logger.isTraceEnabled()) {
            logger.trace("Trying to resolve XML entity with public ID [" + publicId + "] and system ID [" + systemId
                    + "]");
        }
        if (systemId != null && systemId.endsWith(DTD_EXTENSION)) {
            int lastPathSeparator = systemId.lastIndexOf("/");
            for (String DTD_NAME : DTD_NAMES) {
                int dtdNameStart = systemId.indexOf(DTD_NAME);
                if (dtdNameStart > lastPathSeparator) {
                    String dtdFile = systemId.substring(dtdNameStart);
                    if (logger.isTraceEnabled()) {
                        logger.trace("Trying to locate [" + dtdFile + "] in Spring jar");
                    }
                    try {
                        Resource resource = new ClassPathResource(dtdFile, getClass());
                        InputSource source = new InputSource(resource.getInputStream());
                        source.setPublicId(publicId);
                        source.setSystemId(systemId);
                        if (logger.isDebugEnabled()) {
                            logger.debug("Found queries DTD [" + systemId + "] in classpath: " + dtdFile);
                        }
                        return source;
                    } catch (IOException ex) {
                        if (logger.isDebugEnabled()) {
                            logger.debug(
                                    "Could not resolve queries DTD [" + systemId + "]: not found in class path",
                                    ex);
                        }
                    }

                }
            }
        }

        // Use the default behavior -> download from website or wherever.
        return null;
    }

    @Override
    public String toString() {
        return "EntityResolver for DTDs " + Arrays.toString(DTD_NAMES);
    }

}