001/* FilterOutputStream.java -- Parent class for output streams that filter
002   Copyright (C) 1998, 1999, 2001, 2003, 2005  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.io;
040
041/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
042 * "The Java Language Specification", ISBN 0-201-63451-1
043 * Status:  Complete to version 1.1.
044 */
045
046/**
047  * This class is the common superclass of output stream classes that
048  * filter the output they write.  These classes typically transform the
049  * data in some way prior to writing it out to another underlying
050  * <code>OutputStream</code>.  This class simply overrides all the
051  * methods in <code>OutputStream</code> to redirect them to the
052  * underlying stream.  Subclasses provide actual filtering.
053  *
054  * @author Aaron M. Renn (arenn@urbanophile.com)
055  * @author Tom Tromey (tromey@cygnus.com)
056  */
057public class FilterOutputStream extends OutputStream
058{
059  /**
060    * This is the subordinate <code>OutputStream</code> that this class
061    * redirects its method calls to.
062    */
063  protected OutputStream out;
064
065  /**
066    * This method initializes an instance of <code>FilterOutputStream</code>
067    * to write to the specified subordinate <code>OutputStream</code>.
068    *
069    * @param out The <code>OutputStream</code> to write to
070    */
071  public FilterOutputStream(OutputStream out)
072  {
073    this.out = out;
074  }
075
076  /**
077    * This method closes the underlying <code>OutputStream</code>.  Any
078    * further attempts to write to this stream may throw an exception.
079    *
080    * @exception IOException If an error occurs
081    */
082  public void close() throws IOException
083  {
084    flush();
085    out.close();
086  }
087
088  /**
089    * This method attempt to flush all buffered output to be written to the
090    * underlying output sink.
091    *
092    * @exception IOException If an error occurs
093    */
094  public void flush() throws IOException
095  {
096    out.flush();
097  }
098
099  /**
100    * This method writes a single byte of output to the underlying
101    * <code>OutputStream</code>.
102    *
103    * @param b The byte to write, passed as an int.
104    *
105    * @exception IOException If an error occurs
106    */
107  public void write(int b) throws IOException
108  {
109    out.write(b);
110  }
111
112  /**
113    * This method writes all the bytes in the specified array to the underlying
114    * <code>OutputStream</code>.  It does this by calling the three parameter
115    * version of this method - <code>write(byte[], int, int)</code> in this
116    * class instead of writing to the underlying <code>OutputStream</code>
117    * directly.  This allows most subclasses to avoid overriding this method.
118    *
119    * @param buf The byte array to write bytes from
120    *
121    * @exception IOException If an error occurs
122    */
123  public void write(byte[] buf) throws IOException
124  {
125    // Don't do checking here, per Java Lang Spec.
126    write(buf, 0, buf.length);
127  }
128
129  /**
130    * This method calls the <code>write(int)</code> method <code>len</code>
131    * times for all bytes from the array <code>buf</code> starting at index
132    * <code>offset</code>. Subclasses should overwrite this method to get a
133    * more efficient implementation.
134    *
135    * @param buf The byte array to write bytes from
136    * @param offset The index into the array to start writing bytes from
137    * @param len The number of bytes to write
138    *
139    * @exception IOException If an error occurs
140    */
141  public void write(byte[] buf, int offset, int len) throws IOException
142  {
143    // Don't do checking here, per Java Lang Spec.
144    for (int i=0; i < len; i++)
145      write(buf[offset + i]);
146
147  }
148
149} // class FilterOutputStream