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
18 package org.apache.commons.io.output;
19
20 import java.io.IOException;
21 import java.io.OutputStream;
22
23 import org.apache.commons.io.IOUtils;
24
25 /**
26 * Forwards data to a stream that has been associated with this thread.
27 */
28 public class DemuxOutputStream extends OutputStream {
29
30 private final InheritableThreadLocal<OutputStream> outputStreamThreadLocal = new InheritableThreadLocal<>();
31
32 /**
33 * Construct a new instance.
34 */
35 public DemuxOutputStream() {
36 // empty
37 }
38
39 /**
40 * Binds the specified stream to the current thread.
41 *
42 * @param output 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 if an error occurs.
55 */
56 @SuppressWarnings("resource") // we actually close the stream here
57 @Override
58 public void close() throws IOException {
59 IOUtils.close(outputStreamThreadLocal.get());
60 }
61
62 /**
63 * Flushes stream associated with current thread.
64 *
65 * @throws IOException if an error occurs.
66 */
67 @Override
68 public void flush() throws IOException {
69 @SuppressWarnings("resource")
70 final OutputStream output = outputStreamThreadLocal.get();
71 if (null != output) {
72 output.flush();
73 }
74 }
75
76 /**
77 * Writes byte to stream associated with current thread.
78 *
79 * @param ch the byte to write to stream.
80 * @throws IOException if an error occurs.
81 */
82 @Override
83 public void write(final int ch) throws IOException {
84 @SuppressWarnings("resource")
85 final OutputStream output = outputStreamThreadLocal.get();
86 if (null != output) {
87 output.write(ch);
88 }
89 }
90 }