org.roda.core.common.RodaEntityResolver.java Source code

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Here is the source code for org.roda.core.common.RodaEntityResolver.java

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/**
 * The contents of this file are subject to the license and copyright
 * detailed in the LICENSE file at the root of the source
 * tree and available online at
 *
 * https://github.com/keeps/roda
 */
package org.roda.core.common;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringReader;
import java.net.URI;
import java.nio.file.Paths;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

import org.apache.commons.io.IOUtils;
import org.roda.core.RodaCoreFactory;
import org.roda.core.data.common.RodaConstants;
import org.roda.core.data.exceptions.NotFoundException;
import org.roda.core.data.v2.common.Pair;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

public class RodaEntityResolver implements EntityResolver {

    private static CacheLoader<Pair<String, String>, byte[]> loader = new CacheLoader<Pair<String, String>, byte[]>() {

        @Override
        public byte[] load(Pair<String, String> pair) throws Exception {
            String systemId = pair.getSecond();

            String filename = Paths.get(URI.create(systemId)).getFileName().toString();
            String configurationFile = RodaConstants.CORE_SCHEMAS_FOLDER + "/" + filename;

            try (InputStream in = RodaCoreFactory.getConfigurationFileAsStream(configurationFile);
                    ByteArrayOutputStream out = new ByteArrayOutputStream()) {
                if (in != null) {
                    IOUtils.copy(in, out);
                    return out.toByteArray();
                } else
                    throw new NotFoundException(configurationFile);
            }
        }

    };

    private static LoadingCache<Pair<String, String>, byte[]> cache = CacheBuilder.newBuilder()
            .expireAfterWrite(1, TimeUnit.MINUTES).build(loader);

    @Override
    public InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException {
        try {
            byte[] in = cache.get(Pair.of(publicId, systemId));
            return new InputSource(new ByteArrayInputStream(in));
        } catch (ExecutionException e) {
            if (systemId.endsWith(".dtd")) {
                // ignore DTDs that are not in configuration
                return new InputSource(new StringReader(""));
            } else {
                throw new SAXException("Could not resolve entity", e);
            }
        }
    }
}