| /* GZIPOutputStream.java - Create a file in gzip format |
| Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| package java.util.zip; |
| |
| import java.io.IOException; |
| import java.io.OutputStream; |
| |
| /** |
| * This filter stream is used to compress a stream into a "GZIP" stream. |
| * The "GZIP" format is described in RFC 1952. |
| * |
| * @author John Leuner |
| * @author Tom Tromey |
| * @since JDK 1.1 |
| */ |
| |
| /* Written using on-line Java Platform 1.2 API Specification |
| * and JCL book. |
| * Believed complete and correct. |
| */ |
| |
| public class GZIPOutputStream extends DeflaterOutputStream |
| { |
| /** |
| * CRC-32 value for uncompressed data |
| */ |
| protected CRC32 crc; |
| |
| /** |
| * Creates a GZIPOutputStream with the default buffer size |
| * |
| * @param out The stream to read data (to be compressed) from |
| * |
| */ |
| public GZIPOutputStream(OutputStream out) throws IOException |
| { |
| this(out, 4096); |
| } |
| |
| /** |
| * Creates a GZIPOutputStream with the specified buffer size |
| * |
| * @param out The stream to read compressed data from |
| * @param size Size of the buffer to use |
| */ |
| public GZIPOutputStream(OutputStream out, int size) throws IOException |
| { |
| super(out, new Deflater(Deflater.DEFAULT_COMPRESSION, true), size); |
| crc = new CRC32(); |
| int mod_time = (int) (System.currentTimeMillis() / 1000L); |
| byte[] gzipHeader = |
| { |
| /* The two magic bytes */ |
| (byte) GZIPInputStream.GZIP_MAGIC, |
| (byte) (GZIPInputStream.GZIP_MAGIC >> 8), |
| |
| /* The compression type */ |
| (byte) Deflater.DEFLATED, |
| |
| /* The flags (not set) */ |
| 0, |
| |
| /* The modification time */ |
| (byte) mod_time, (byte) (mod_time >> 8), |
| (byte) (mod_time >> 16), (byte) (mod_time >> 24), |
| |
| /* The extra flags */ |
| 0, |
| |
| /* The OS type (unknown) */ |
| (byte) 255 |
| }; |
| |
| out.write(gzipHeader); |
| // System.err.println("wrote GZIP header (" + gzipHeader.length + " bytes )"); |
| } |
| |
| public synchronized void write(byte[] buf, int off, int len) |
| throws IOException |
| { |
| super.write(buf, off, len); |
| crc.update(buf, off, len); |
| } |
| |
| /** |
| * Writes remaining compressed output data to the output stream |
| * and closes it. |
| */ |
| public void close() throws IOException |
| { |
| finish(); |
| out.close(); |
| } |
| |
| public void finish() throws IOException |
| { |
| super.finish(); |
| |
| int totalin = def.getTotalIn(); |
| int crcval = (int) (crc.getValue() & 0xffffffff); |
| |
| // System.err.println("CRC val is " + Integer.toHexString( crcval ) + " and length " + Integer.toHexString(totalin)); |
| |
| byte[] gzipFooter = |
| { |
| (byte) crcval, (byte) (crcval >> 8), |
| (byte) (crcval >> 16), (byte) (crcval >> 24), |
| |
| (byte) totalin, (byte) (totalin >> 8), |
| (byte) (totalin >> 16), (byte) (totalin >> 24) |
| }; |
| |
| out.write(gzipFooter); |
| // System.err.println("wrote GZIP trailer (" + gzipFooter.length + " bytes )"); |
| } |
| } |