001 /* FilterOutputStream.java -- Parent class for output streams that filter
002 Copyright (C) 1998, 1999, 2001, 2003, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package 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 */
057 public 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