001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.net.io;
019
020import java.io.FilterOutputStream;
021import java.io.IOException;
022import java.io.OutputStream;
023
024/***
025 * This class wraps an output stream, replacing all occurrences
026 * of <CR><LF> (carriage return followed by a linefeed),
027 * which is the NETASCII standard for representing a newline, with the
028 * local line separator representation.  You would use this class to
029 * implement ASCII file transfers requiring conversion from NETASCII.
030 * <p>
031 * Because of the translation process, a call to <code>flush()</code> will
032 * not flush the last byte written if that byte was a carriage
033 * return.  A call to {@link #close  close() }, however, will
034 * flush the carriage return.
035 *
036 *
037 ***/
038
039public final class FromNetASCIIOutputStream extends FilterOutputStream
040{
041    private boolean __lastWasCR;
042
043    /***
044     * Creates a FromNetASCIIOutputStream instance that wraps an existing
045     * OutputStream.
046     *
047     * @param output  The OutputStream to wrap.
048     ***/
049    public FromNetASCIIOutputStream(OutputStream output)
050    {
051        super(output);
052        __lastWasCR = false;
053    }
054
055
056    private void __write(int ch) throws IOException
057    {
058        switch (ch)
059        {
060        case '\r':
061            __lastWasCR = true;
062            // Don't write anything.  We need to see if next one is linefeed
063            break;
064        case '\n':
065            if (__lastWasCR)
066            {
067                out.write(FromNetASCIIInputStream._lineSeparatorBytes);
068                __lastWasCR = false;
069                break;
070            }
071            __lastWasCR = false;
072            out.write('\n');
073            break;
074        default:
075            if (__lastWasCR)
076            {
077                out.write('\r');
078                __lastWasCR = false;
079            }
080            out.write(ch);
081            break;
082        }
083    }
084
085
086    /***
087     * Writes a byte to the stream.    Note that a call to this method
088     * might not actually write a byte to the underlying stream until a
089     * subsequent character is written, from which it can be determined if
090     * a NETASCII line separator was encountered.
091     * This is transparent to the programmer and is only mentioned for
092     * completeness.
093     *
094     * @param ch The byte to write.
095     * @throws IOException If an error occurs while writing to the underlying
096     *            stream.
097     ***/
098    @Override
099    public synchronized void write(int ch)
100    throws IOException
101    {
102        if (FromNetASCIIInputStream._noConversionRequired)
103        {
104            out.write(ch);
105            return ;
106        }
107
108        __write(ch);
109    }
110
111
112    /***
113     * Writes a byte array to the stream.
114     *
115     * @param buffer  The byte array to write.
116     * @throws IOException If an error occurs while writing to the underlying
117     *            stream.
118     ***/
119    @Override
120    public synchronized void write(byte buffer[])
121    throws IOException
122    {
123        write(buffer, 0, buffer.length);
124    }
125
126
127    /***
128     * Writes a number of bytes from a byte array to the stream starting from
129     * a given offset.
130     *
131     * @param buffer  The byte array to write.
132     * @param offset  The offset into the array at which to start copying data.
133     * @param length  The number of bytes to write.
134     * @throws IOException If an error occurs while writing to the underlying
135     *            stream.
136     ***/
137    @Override
138    public synchronized void write(byte buffer[], int offset, int length)
139    throws IOException
140    {
141        if (FromNetASCIIInputStream._noConversionRequired)
142        {
143            // FilterOutputStream method is very slow.
144            //super.write(buffer, offset, length);
145            out.write(buffer, offset, length);
146            return ;
147        }
148
149        while (length-- > 0) {
150            __write(buffer[offset++]);
151        }
152    }
153
154
155    /***
156     * Closes the stream, writing all pending data.
157     *
158     * @throws IOException  If an error occurs while closing the stream.
159     ***/
160    @Override
161    public synchronized void close()
162    throws IOException
163    {
164        if (FromNetASCIIInputStream._noConversionRequired)
165        {
166            super.close();
167            return ;
168        }
169
170        if (__lastWasCR) {
171            out.write('\r');
172        }
173        super.close();
174    }
175}