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TrueZIP is a Java based Virtual File System (VFS) to enable transparent, multi-threaded read/write access to archive files (ZIP, TAR etc.) as if they were directories. Archive files may be arbitrarily nested and the nesting level is only limited by heap and file system size.
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/*
 * Copyright (C) 2006-2010 Schlichtherle IT Services
 *
 * 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.schlichtherle.io.archive.tar;

import de.schlichtherle.io.archive.*;
import de.schlichtherle.io.archive.spi.*;
import de.schlichtherle.io.rof.*;

import java.io.*;
import java.util.zip.*;

import javax.swing.*;

/**
 * An archive driver which builds TAR files compressed with GZIP.
 * Instances of this class are immutable.
 * 
 * @author Christian Schlichtherle
 * @version $Id: TarGZipDriver.java,v 1.4 2010/08/20 13:09:44 christian_schlichtherle Exp $
 * @since TrueZIP 6.0
 */
public class TarGZipDriver extends TarDriver {

    private static final long serialVersionUID = 7736164529936091928L;

    private static final int BUFSIZE = 4096;

    /**
     * The default compression level to use when writing a GZIP output stream,
     * which is {@value}.
     */
    public static final int DEFAULT_LEVEL = Deflater.BEST_COMPRESSION;

    private final int level;

    /**
     * Equivalent to {@link #TarGZipDriver(String, Icon, Icon, int)
     * this(DEFAULT_CHARSET, null, null, DEFAULT_LEVEL)}.
     */
    public TarGZipDriver() {
        this(DEFAULT_CHARSET, null, null, DEFAULT_LEVEL);
    }

    /**
     * Equivalent to {@link #TarGZipDriver(String, Icon, Icon, int)
     * this(charset, null, null, DEFAULT_LEVEL)}.
     */
    public TarGZipDriver(String charset) {
        this(charset, null, null, DEFAULT_LEVEL);
    }

    /**
     * Equivalent to {@link #TarGZipDriver(String, Icon, Icon, int)
     * this(DEFAULT_CHARSET, null, null, level)}.
     */
    public TarGZipDriver(int level) {
        this(DEFAULT_CHARSET, null, null, level);
    }

    /**
     * Constructs a new TAR.GZ driver.
     *
     * @param level The compression level to use when writing a GZIP output
     *        stream.
     * @throws IllegalArgumentException If {@code level} is not in the
     *         range [{@value java.util.zip.Deflater#BEST_SPEED}..{@value java.util.zip.Deflater#BEST_COMPRESSION}]
     *         and is not {@value java.util.zip.Deflater#DEFAULT_COMPRESSION}.
     */
    public TarGZipDriver(
            final String charset,
            final Icon openIcon,
            final Icon closedIcon,
            final int level) {
        super(charset, null, null);
        if (    (   level < Deflater.BEST_SPEED
                 || level > Deflater.BEST_COMPRESSION)
                && level != Deflater.DEFAULT_COMPRESSION)
            throw new IllegalArgumentException();
        this.level = level;
    }

    /**
     * Returns the value of the property {@code preambled} which was 
     * provided to the constructor.
     */
    public final int getLevel() {
        return level;
    }

    //
    // Driver implementation:
    //

    protected InputStream createInputStream(Archive archive, ReadOnlyFile rof)
    throws IOException {
        return new GZIPInputStream(
                super.createInputStream(archive, rof),
                BUFSIZE);
    }

    protected TarOutputArchive createTarOutputArchive(
            final Archive archive,
            final OutputStream out,
            final TarInputArchive source)
    throws IOException {
        return super.createTarOutputArchive(
                archive,
                new GZIPOutputStream(out, BUFSIZE, level),
                source);
    }

    public static class GZIPOutputStream
            extends java.util.zip.GZIPOutputStream {
        /**
         * Constructs a new {@code GZIPOutputStream} with the specified
         * output stream, buffer size and compression level.
         *
         * @param level The compression level for the {@link Deflater}
         *        ({@value java.util.zip.Deflater#BEST_SPEED}..{@value java.util.zip.Deflater#BEST_COMPRESSION}).
         * @throws IOException If an I/O error occurs.
         * @throws IllegalArgumentException if {@code size} is <= 0.
         * @throws IllegalArgumentException If {@code level} is not in the
         *         range [{@value java.util.zip.Deflater#BEST_SPEED}..{@value java.util.zip.Deflater#BEST_COMPRESSION}]
         *         and is not {@value java.util.zip.Deflater#DEFAULT_COMPRESSION}.
         */
        public GZIPOutputStream(OutputStream out, int size, int level)
        throws IOException {
            super(out, size);
            def.setLevel(level);
        }
    }
}