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    1   /*
    2    * Copyright (c) 1994, 2011, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   15    * accompanied this code).
   16    *
   17    * You should have received a copy of the GNU General Public License version
   18    * 2 along with this work; if not, write to the Free Software Foundation,
   19    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   
   26   package java.io;
   27   
   28   /**
   29    * This class is the superclass of all classes that filter output
   30    * streams. These streams sit on top of an already existing output
   31    * stream (the <i>underlying</i> output stream) which it uses as its
   32    * basic sink of data, but possibly transforming the data along the
   33    * way or providing additional functionality.
   34    * <p>
   35    * The class <code>FilterOutputStream</code> itself simply overrides
   36    * all methods of <code>OutputStream</code> with versions that pass
   37    * all requests to the underlying output stream. Subclasses of
   38    * <code>FilterOutputStream</code> may further override some of these
   39    * methods as well as provide additional methods and fields.
   40    *
   41    * @author  Jonathan Payne
   42    * @since   JDK1.0
   43    */
   44   public
   45   class FilterOutputStream extends OutputStream {
   46       /**
   47        * The underlying output stream to be filtered.
   48        */
   49       protected OutputStream out;
   50   
   51       /**
   52        * Creates an output stream filter built on top of the specified
   53        * underlying output stream.
   54        *
   55        * @param   out   the underlying output stream to be assigned to
   56        *                the field <tt>this.out</tt> for later use, or
   57        *                <code>null</code> if this instance is to be
   58        *                created without an underlying stream.
   59        */
   60       public FilterOutputStream(OutputStream out) {
   61           this.out = out;
   62       }
   63   
   64       /**
   65        * Writes the specified <code>byte</code> to this output stream.
   66        * <p>
   67        * The <code>write</code> method of <code>FilterOutputStream</code>
   68        * calls the <code>write</code> method of its underlying output stream,
   69        * that is, it performs <tt>out.write(b)</tt>.
   70        * <p>
   71        * Implements the abstract <tt>write</tt> method of <tt>OutputStream</tt>.
   72        *
   73        * @param      b   the <code>byte</code>.
   74        * @exception  IOException  if an I/O error occurs.
   75        */
   76       public void write(int b) throws IOException {
   77           out.write(b);
   78       }
   79   
   80       /**
   81        * Writes <code>b.length</code> bytes to this output stream.
   82        * <p>
   83        * The <code>write</code> method of <code>FilterOutputStream</code>
   84        * calls its <code>write</code> method of three arguments with the
   85        * arguments <code>b</code>, <code>0</code>, and
   86        * <code>b.length</code>.
   87        * <p>
   88        * Note that this method does not call the one-argument
   89        * <code>write</code> method of its underlying stream with the single
   90        * argument <code>b</code>.
   91        *
   92        * @param      b   the data to be written.
   93        * @exception  IOException  if an I/O error occurs.
   94        * @see        java.io.FilterOutputStream#write(byte[], int, int)
   95        */
   96       public void write(byte b[]) throws IOException {
   97           write(b, 0, b.length);
   98       }
   99   
  100       /**
  101        * Writes <code>len</code> bytes from the specified
  102        * <code>byte</code> array starting at offset <code>off</code> to
  103        * this output stream.
  104        * <p>
  105        * The <code>write</code> method of <code>FilterOutputStream</code>
  106        * calls the <code>write</code> method of one argument on each
  107        * <code>byte</code> to output.
  108        * <p>
  109        * Note that this method does not call the <code>write</code> method
  110        * of its underlying input stream with the same arguments. Subclasses
  111        * of <code>FilterOutputStream</code> should provide a more efficient
  112        * implementation of this method.
  113        *
  114        * @param      b     the data.
  115        * @param      off   the start offset in the data.
  116        * @param      len   the number of bytes to write.
  117        * @exception  IOException  if an I/O error occurs.
  118        * @see        java.io.FilterOutputStream#write(int)
  119        */
  120       public void write(byte b[], int off, int len) throws IOException {
  121           if ((off | len | (b.length - (len + off)) | (off + len)) < 0)
  122               throw new IndexOutOfBoundsException();
  123   
  124           for (int i = 0 ; i < len ; i++) {
  125               write(b[off + i]);
  126           }
  127       }
  128   
  129       /**
  130        * Flushes this output stream and forces any buffered output bytes
  131        * to be written out to the stream.
  132        * <p>
  133        * The <code>flush</code> method of <code>FilterOutputStream</code>
  134        * calls the <code>flush</code> method of its underlying output stream.
  135        *
  136        * @exception  IOException  if an I/O error occurs.
  137        * @see        java.io.FilterOutputStream#out
  138        */
  139       public void flush() throws IOException {
  140           out.flush();
  141       }
  142   
  143       /**
  144        * Closes this output stream and releases any system resources
  145        * associated with the stream.
  146        * <p>
  147        * The <code>close</code> method of <code>FilterOutputStream</code>
  148        * calls its <code>flush</code> method, and then calls the
  149        * <code>close</code> method of its underlying output stream.
  150        *
  151        * @exception  IOException  if an I/O error occurs.
  152        * @see        java.io.FilterOutputStream#flush()
  153        * @see        java.io.FilterOutputStream#out
  154        */
  155       public void close() throws IOException {
  156           try {
  157             flush();
  158           } catch (IOException ignored) {
  159           }
  160           out.close();
  161       }
  162   }

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