de.tudarmstadt.ukp.dkpro.core.api.resources.CompressionUtils.java Source code

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/*******************************************************************************
 * Copyright 2012
 * Ubiquitous Knowledge Processing (UKP) Lab
 * Technische Universitt Darmstadt
 * 
 * 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.tudarmstadt.ukp.dkpro.core.api.resources;

import static org.apache.commons.io.FileUtils.forceMkdir;
import static de.tudarmstadt.ukp.dkpro.core.api.resources.CompressionMethod.*;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

import org.apache.commons.compress.compressors.bzip2.BZip2CompressorInputStream;
import org.apache.commons.compress.compressors.bzip2.BZip2CompressorOutputStream;
import org.apache.commons.compress.compressors.xz.XZCompressorInputStream;
import org.apache.commons.compress.compressors.xz.XZCompressorOutputStream;

/**
 * Utility methods for dealing with compressed data.
 * 
 * @author Richard Eckart de Castilho
 */
public class CompressionUtils {
    /**
     * Get an uncompressed input stream for a given input stream created for a particular location.
     * 
     * @param aLocation a resource location (e.g. a path, url, etc.)
     * @param aStream a raw stream of potentially compressed data.
     * @return stream wrapped with a decompressing stream.
     */
    public static InputStream getInputStream(String aLocation, InputStream aStream) throws IOException {
        String lcLocation = aLocation.toLowerCase();
        if (lcLocation.endsWith(GZIP.getExtension())) {
            return new GZIPInputStream(aStream);
        } else if (lcLocation.endsWith(BZIP2.getExtension()) || lcLocation.endsWith(".bzip2")) {
            return new BZip2CompressorInputStream(aStream);
        } else if (lcLocation.endsWith(XZ.getExtension())) {
            return new XZCompressorInputStream(aStream);
        } else {
            return aStream;
        }
    }

    /**
     * Make sure the target directory exists and get a stream writing to the specified file within.
     * If the file name ends with a typical extension for compressed files, the stream will be
     * compressed.
     * 
     * @param aFile
     *            the target file.
     * @return a stream to write to.
     * 
     * @see CompressionMethod
     */
    public static OutputStream getOutputStream(File aFile) throws IOException {
        // Create parent folders for output file and set up stream
        if (aFile.getParentFile() != null) {
            forceMkdir(aFile.getParentFile());
        }

        String lcFilename = aFile.getName().toLowerCase();

        OutputStream os = new FileOutputStream(aFile);
        if (lcFilename.endsWith(GZIP.getExtension())) {
            os = new GZIPOutputStream(os);
        } else if (lcFilename.endsWith(BZIP2.getExtension()) || lcFilename.endsWith(".bzip2")) {
            os = new BZip2CompressorOutputStream(os);
        } else if (lcFilename.endsWith(XZ.getExtension())) {
            os = new XZCompressorOutputStream(os);
        }
        return os;
    }
}