org.lenskit.util.io.CompressedByteSource.java Source code

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Here is the source code for org.lenskit.util.io.CompressedByteSource.java

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/*
 * LensKit, an open-source toolkit for recommender systems.
 * Copyright 2014-2017 LensKit contributors (see CONTRIBUTORS.md)
 * Copyright 2010-2014 Regents of the University of Minnesota
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
package org.lenskit.util.io;

import com.google.common.io.ByteSource;
import org.apache.commons.compress.compressors.CompressorException;
import org.apache.commons.compress.compressors.CompressorStreamFactory;

import java.io.IOException;
import java.io.InputStream;

/**
 * A Guava byte source that decompresses data from an underlying source.
 */
public class CompressedByteSource extends ByteSource {
    private final ByteSource delegate;
    private final String compName;

    /**
     * Construct a compressed byte source.
     * @param inner The underlying byte source.
     * @param comp The compression name.
     * @see org.apache.commons.compress.compressors.CompressorStreamFactory
     */
    public CompressedByteSource(ByteSource inner, String comp) {
        delegate = inner;
        compName = comp;
    }

    @Override
    public InputStream openStream() throws IOException {
        CompressorStreamFactory factory = new CompressorStreamFactory();
        InputStream base = delegate.openStream();
        try {
            return factory.createCompressorInputStream(compName, base);
        } catch (CompressorException e) {
            throw new IOException("Could not create compressor", e);
        }
    }
}