1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.net.io;
19
20 import java.io.FilterOutputStream;
21 import java.io.IOException;
22 import java.io.OutputStream;
23
24 /**
25 * This class wraps an output stream, replacing all singly occurring <LF> (linefeed) characters with <CR><LF> (carriage return followed by
26 * linefeed), which is the NETASCII standard for representing a newline. You would use this class to implement ASCII file transfers requiring conversion to
27 * NETASCII.
28 */
29
30 public final class ToNetASCIIOutputStream extends FilterOutputStream {
31 private boolean lastWasCR;
32
33 /**
34 * Creates a ToNetASCIIOutputStream instance that wraps an existing OutputStream.
35 *
36 * @param output The OutputStream to wrap.
37 */
38 public ToNetASCIIOutputStream(final OutputStream output) {
39 super(output);
40 lastWasCR = false;
41 }
42
43 /**
44 * Writes a byte array to the stream.
45 *
46 * @param buffer The byte array to write.
47 * @throws IOException If an error occurs while writing to the underlying stream.
48 */
49 @Override
50 public synchronized void write(final byte buffer[]) throws IOException {
51 write(buffer, 0, buffer.length);
52 }
53
54 /**
55 * Writes a number of bytes from a byte array to the stream starting from a given offset.
56 *
57 * @param buffer The byte array to write.
58 * @param offset The offset into the array at which to start copying data.
59 * @param length The number of bytes to write.
60 * @throws IOException If an error occurs while writing to the underlying stream.
61 */
62 @Override
63 public synchronized void write(final byte buffer[], int offset, int length) throws IOException {
64 while (length-- > 0) {
65 write(buffer[offset++]);
66 }
67 }
68
69 /**
70 * Writes a byte to the stream. Note that a call to this method may result in multiple writes to the underlying input stream in order to convert naked
71 * newlines to NETASCII line separators. This is transparent to the programmer and is only mentioned for completeness.
72 *
73 * @param ch The byte to write.
74 * @throws IOException If an error occurs while writing to the underlying stream.
75 */
76 @Override
77 public synchronized void write(final int ch) throws IOException {
78 switch (ch) {
79 case '\r':
80 lastWasCR = true;
81 out.write('\r');
82 return;
83 case '\n':
84 if (!lastWasCR) {
85 out.write('\r');
86 }
87 //$FALL-THROUGH$
88 default:
89 lastWasCR = false;
90 out.write(ch);
91 }
92 }
93
94 }