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 * https://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
29 private final InheritableThreadLocal<OutputStream> outputStreamThreadLocal = new InheritableThreadLocal<>();
30
31 /**
32 * Construct a new instance.
33 */
34 public DemuxOutputStream() {
35 // empty
36 }
37
38 /**
39 * Binds the specified stream to the current thread.
40 *
41 * @param output
42 * the stream to bind
43 * @return the OutputStream that was previously active
44 */
45 public OutputStream bindStream(final OutputStream output) {
46 final OutputStream stream = outputStreamThreadLocal.get();
47 outputStreamThreadLocal.set(output);
48 return stream;
49 }
50
51 /**
52 * Closes stream associated with current thread.
53 *
54 * @throws IOException
55 * if an error occurs
56 */
57 @SuppressWarnings("resource") // we actually close the stream here
58 @Override
59 public void close() throws IOException {
60 IOUtils.close(outputStreamThreadLocal.get());
61 }
62
63 /**
64 * Flushes stream associated with current thread.
65 *
66 * @throws IOException
67 * if an error occurs
68 */
69 @Override
70 public void flush() throws IOException {
71 @SuppressWarnings("resource")
72 final OutputStream output = outputStreamThreadLocal.get();
73 if (null != output) {
74 output.flush();
75 }
76 }
77
78 /**
79 * Writes byte to stream associated with current thread.
80 *
81 * @param ch
82 * the byte to write to stream
83 * @throws IOException
84 * if an error occurs
85 */
86 @Override
87 public void write(final int ch) throws IOException {
88 @SuppressWarnings("resource")
89 final OutputStream output = outputStreamThreadLocal.get();
90 if (null != output) {
91 output.write(ch);
92 }
93 }
94 }