gomp-20050608-branch/libjava/java/util/zip/GZIPOutputStream.java

   1 /* GZIPOutputStream.java - Create a file in gzip format
   2    Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38 package java.util.zip;
  39
  40 import java.io.IOException;
  41 import java.io.OutputStream;
  42
  43 /**
  44  * This filter stream is used to compress a stream into a "GZIP" stream.
  45  * The "GZIP" format is described in RFC 1952.
  46  *
  47  * @author John Leuner
  48  * @author Tom Tromey
  49  * @since JDK 1.1
  50  */
  51
  52 /* Written using on-line Java Platform 1.2 API Specification
  53  * and JCL book.
  54  * Believed complete and correct.
  55  */
  56
  57 public class GZIPOutputStream extends DeflaterOutputStream
  58 {
  59   /**
  60    * CRC-32 value for uncompressed data
  61    */
  62   protected CRC32 crc;
  63
  64   /**
  65    * Creates a GZIPOutputStream with the default buffer size
  66    *
  67    * @param out The stream to read data (to be compressed) from
  68    *
  69    */
  70   public GZIPOutputStream(OutputStream out) throws IOException
  71   {
  72     this(out, 4096);
  73   }
  74
  75   /**
  76    * Creates a GZIPOutputStream with the specified buffer size
  77    *
  78    * @param out The stream to read compressed data from
  79    * @param size Size of the buffer to use
  80    */
  81   public GZIPOutputStream(OutputStream out, int size) throws IOException
  82   {
  83     super(out, new Deflater(Deflater.DEFAULT_COMPRESSION, true), size);
  84     crc = new CRC32();
  85     put2(GZIPInputStream.GZIP_MAGIC);
  86     out.write(GZIPInputStream.Z_DEFLATED);
  87     // No flags for now.
  88     out.write(0);
  89     // No time either.
  90     put2(0);
  91     put2(0);
  92     // No xflags either.
  93     out.write(0);
  94     // FIXME: unknown OS.
  95     out.write(255);
  96   }
  97
  98   public synchronized void write(int bval) throws IOException
  99   {
 100     super.write(bval);
 101     crc.update(bval);
 102   }
 103
 104   public synchronized void write(byte[] buf) throws IOException
 105   {
 106     write(buf, 0, buf.length);
 107   }
 108
 109   public synchronized void write(byte[] buf, int off, int len)
 110     throws IOException
 111   {
 112     super.write(buf, off, len);
 113     crc.update(buf, off, len);
 114   }
 115
 116   /**
 117    * Writes remaining compressed output data to the output stream
 118    * and closes it.
 119    */
 120   public void close() throws IOException
 121   {
 122     finish();
 123     out.close();
 124   }
 125
 126   public void finish() throws IOException
 127   {
 128     super.finish();
 129     put4((int) crc.getValue());
 130     put4(def.getTotalIn());
 131   }
 132
 133   private final void put2(int i) throws IOException
 134   {
 135     out.write(i);
 136     out.write(i >> 8);
 137   }
 138
 139   private final void put4 (int i) throws IOException
 140   {
 141     out.write(i);
 142     out.write(i >> 8);
 143     out.write(i >> 16);
 144     out.write(i >> 24);
 145   }
 146 }