it.tidalwave.northernwind.core.impl.util.CachedURIResolver.java Source code

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Here is the source code for it.tidalwave.northernwind.core.impl.util.CachedURIResolver.java

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/*
 * #%L
 * *********************************************************************************************************************
 *
 * NorthernWind - lightweight CMS
 * http://northernwind.tidalwave.it - git clone https://bitbucket.org/tidalwave/northernwind-src.git
 * %%
 * Copyright (C) 2011 - 2018 Tidalwave s.a.s. (http://tidalwave.it)
 * %%
 * *********************************************************************************************************************
 *
 * 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.
 *
 * *********************************************************************************************************************
 *
 *
 * *********************************************************************************************************************
 * #L%
 */
package it.tidalwave.northernwind.core.impl.util;

import javax.annotation.Nonnull;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.net.URL;
import javax.xml.transform.Source;
import javax.xml.transform.TransformerException;
import javax.xml.transform.URIResolver;
import javax.xml.transform.stream.StreamSource;
import org.apache.commons.io.FileUtils;
import lombok.Getter;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;
import static it.tidalwave.northernwind.util.UrlEncoding.*;

/***********************************************************************************************************************
 *
 * @author  Fabrizio Giudici
 *
 **********************************************************************************************************************/
@Slf4j
public class CachedURIResolver implements URIResolver {
    @Getter
    @Setter
    private String cacheFolderPath = System.getProperty("java.io.tmpdir") + "/CachedURIResolver";

    @Getter
    @Setter
    private long expirationTime = 60 * 60 * 1000L; // 1 hour

    @Getter
    @Setter
    private int connectionTimeout = 10 * 1000; // 10 secs

    @Getter
    @Setter
    private int readTimeout = 10 * 1000; // 10 secs

    /*******************************************************************************************************************
     *
     ******************************************************************************************************************/
    @Override
    public Source resolve(final String href, final String base) throws TransformerException {
        try {
            log.info("resolve({}, {})", href, base);

            final File cacheFolder = new File(cacheFolderPath);

            if (!cacheFolder.exists()) {
                mkdirs(cacheFolder);
            }

            final File cachedFile = new File(cacheFolder, encodedUtf8(href));
            final long elapsed = System.currentTimeMillis() - cachedFile.lastModified();

            log.debug(">>>> cached file is {} elapsed time is {} msec", cachedFile, elapsed);

            if (!cachedFile.exists() || (elapsed > expirationTime)) {
                cacheDocument(cachedFile, href);
            }

            return new StreamSource(new FileInputStream(cachedFile));
        } catch (IOException e) {
            throw new TransformerException(e);
        }
    }

    /*******************************************************************************************************************
     *
     ******************************************************************************************************************/
    private void cacheDocument(final @Nonnull File cachedFile, final @Nonnull String href) throws IOException {
        log.debug(">>>> caching external document to {}", cachedFile);
        final File tempFile = File.createTempFile("temp", ".txt", new File(cacheFolderPath));
        tempFile.deleteOnExit();
        log.debug(">>>> waiting for lock...");

        try (final FileChannel channel = new RandomAccessFile(tempFile, "rw").getChannel();
                final FileLock lock = channel.lock()) {
            log.debug(">>>> got lock: {}", lock);
            FileUtils.copyURLToFile(new URL(href), tempFile, connectionTimeout, readTimeout);
            rename(tempFile, cachedFile);
        } catch (IOException e) {
            if (cachedFile.exists()) {
                log.warn("Error while retrieving document from {}: {} - using previously cached file", href,
                        e.toString());
            } else {
                throw e;
            }
        }

        log.debug(">>>> done");
    }

    /*******************************************************************************************************************
     *
     ******************************************************************************************************************/
    private static void mkdirs(final @Nonnull File folder) throws IOException {
        if (!folder.mkdirs()) {
            throw new IOException("Cannot mkdirs for " + folder);
        }
    }

    /*******************************************************************************************************************
     *
     ******************************************************************************************************************/
    private static void rename(final @Nonnull File from, final @Nonnull File to) throws IOException {
        if (!from.renameTo(to)) {
            throw new IOException("Cannot rename " + from + " to " + to);
        }
    }
}