001    /* FilterWriter.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 character stream classes 
048      * that 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>Writer</code>.  This class simply overrides all the 
051      * methods in <code>Writer</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 abstract class FilterWriter extends Writer
058    {
059      /**
060        * This is the subordinate <code>Writer</code> that this class
061        * redirects its method calls to.
062        */
063      protected Writer out;
064    
065      /**
066        * This method initializes an instance of <code>FilterWriter</code>
067        * to write to the specified subordinate <code>Writer</code>.
068        * The given <code>Writer</code> will be used as <code>lock</code> for
069        * the newly created <code>FilterWriter</code>.
070        *
071        * @param out The <code>Writer</code> to write to
072        */
073      protected FilterWriter(Writer out)
074      {
075        super(out.lock);
076        this.out = out;
077      }
078    
079      /**
080        * This method closes the underlying <code>Writer</code>.  Any
081        * further attempts to write to this stream may throw an exception.
082        *
083        * @exception IOException If an error occurs
084        */
085      public void close() throws IOException
086      {
087        out.close();
088      }
089    
090      /**
091        * This method attempt to flush all buffered output to be written to the
092        * underlying output sink.
093        *
094        * @exception IOException If an error occurs
095        */
096      public void flush() throws IOException
097      {
098        out.flush();
099      }
100    
101      /**
102        * This method writes a single char of output to the underlying
103        * <code>Writer</code>.
104        *
105        * @param b The char to write, passed as an int.
106        *
107        * @exception IOException If an error occurs
108        */
109      public void write(int b) throws IOException
110      {
111        out.write(b);
112      }
113    
114      /**
115        * This method writes <code>len</code> chars from the array <code>buf</code>
116        * starting at index <code>offset</code> to the underlying
117        * <code>Writer</code>.
118        *
119        * @param buf The char array to write chars from
120        * @param offset The index into the array to start writing chars from
121        * @param len The number of chars to write
122        *
123        * @exception IOException If an error occurs
124        */
125      public void write(char[] buf, int offset, int len) throws IOException
126      {
127        out.write(buf, offset, len);
128      }
129    
130      /**
131        * This method writes <code>len</code> chars from the <code>String</code>
132        * starting at position <code>offset</code>.
133        *
134        * @param str The <code>String</code> that is to be written
135        * @param offset The character offset into the <code>String</code> 
136        * to start writing from
137        * @param len The number of chars to write
138        *
139        * @exception IOException If an error occurs
140        */
141      public void write(String str, int offset, int len) throws IOException
142      {
143        out.write(str, offset, len);
144      }
145    
146    } // class FilterWriter
147