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
018 package org.apache.commons.net.io;
019
020 import java.io.FilterOutputStream;
021 import java.io.IOException;
022 import java.io.OutputStream;
023
024 /***
025 * This class wraps an output stream, replacing all singly occurring
026 * <LF> (linefeed) characters with <CR><LF> (carriage return
027 * followed by linefeed), which is the NETASCII standard for representing
028 * a newline.
029 * You would use this class to implement ASCII file transfers requiring
030 * conversion to NETASCII.
031 * <p>
032 * <p>
033 ***/
034
035 public final class ToNetASCIIOutputStream extends FilterOutputStream
036 {
037 private boolean __lastWasCR;
038
039 /***
040 * Creates a ToNetASCIIOutputStream instance that wraps an existing
041 * OutputStream.
042 * <p>
043 * @param output The OutputStream to wrap.
044 ***/
045 public ToNetASCIIOutputStream(OutputStream output)
046 {
047 super(output);
048 __lastWasCR = false;
049 }
050
051
052 /***
053 * Writes a byte to the stream. Note that a call to this method
054 * may result in multiple writes to the underlying input stream in order
055 * to convert naked newlines to NETASCII line separators.
056 * This is transparent to the programmer and is only mentioned for
057 * completeness.
058 * <p>
059 * @param ch The byte to write.
060 * @exception IOException If an error occurs while writing to the underlying
061 * stream.
062 ***/
063 @Override
064 public synchronized void write(int ch)
065 throws IOException
066 {
067 switch (ch)
068 {
069 case '\r':
070 __lastWasCR = true;
071 out.write('\r');
072 return ;
073 case '\n':
074 if (!__lastWasCR) {
075 out.write('\r');
076 }
077 //$FALL-THROUGH$
078 default:
079 __lastWasCR = false;
080 out.write(ch);
081 return ;
082 }
083 }
084
085
086 /***
087 * Writes a byte array to the stream.
088 * <p>
089 * @param buffer The byte array to write.
090 * @exception IOException If an error occurs while writing to the underlying
091 * stream.
092 ***/
093 @Override
094 public synchronized void write(byte buffer[])
095 throws IOException
096 {
097 write(buffer, 0, buffer.length);
098 }
099
100
101 /***
102 * Writes a number of bytes from a byte array to the stream starting from
103 * a given offset.
104 * <p>
105 * @param buffer The byte array to write.
106 * @param offset The offset into the array at which to start copying data.
107 * @param length The number of bytes to write.
108 * @exception IOException If an error occurs while writing to the underlying
109 * stream.
110 ***/
111 @Override
112 public synchronized void write(byte buffer[], int offset, int length)
113 throws IOException
114 {
115 while (length-- > 0) {
116 write(buffer[offset++]);
117 }
118 }
119
120 }