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 package org.apache.commons.io.output;
18
19 import java.io.IOException;
20 import java.io.OutputStream;
21
22 import org.apache.commons.io.IOUtils;
23
24 /**
25 * Forwards data to a stream that has been associated with this thread.
26 */
27 public class DemuxOutputStream extends OutputStream {
28 private final InheritableThreadLocal<OutputStream> outputStreamThreadLocal = new InheritableThreadLocal<>();
29
30 /**
31 * Binds the specified stream to the current thread.
32 *
33 * @param output
34 * the stream to bind
35 * @return the OutputStream that was previously active
36 */
37 public OutputStream bindStream(final OutputStream output) {
38 final OutputStream stream = outputStreamThreadLocal.get();
39 outputStreamThreadLocal.set(output);
40 return stream;
41 }
42
43 /**
44 * Closes stream associated with current thread.
45 *
46 * @throws IOException
47 * if an error occurs
48 */
49 @SuppressWarnings("resource") // we actually close the stream here
50 @Override
51 public void close() throws IOException {
52 IOUtils.close(outputStreamThreadLocal.get());
53 }
54
55 /**
56 * Flushes stream associated with current thread.
57 *
58 * @throws IOException
59 * if an error occurs
60 */
61 @Override
62 public void flush() throws IOException {
63 @SuppressWarnings("resource")
64 final OutputStream output = outputStreamThreadLocal.get();
65 if (null != output) {
66 output.flush();
67 }
68 }
69
70 /**
71 * Writes byte to stream associated with current thread.
72 *
73 * @param ch
74 * the byte to write to stream
75 * @throws IOException
76 * if an error occurs
77 */
78 @Override
79 public void write(final int ch) throws IOException {
80 @SuppressWarnings("resource")
81 final OutputStream output = outputStreamThreadLocal.get();
82 if (null != output) {
83 output.write(ch);
84 }
85 }
86 }