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.input;
18
19 import static org.apache.commons.io.IOUtils.EOF;
20
21 import java.io.IOException;
22 import java.io.InputStream;
23
24 import org.apache.commons.io.IOUtils;
25
26 /**
27 * Data written to this stream is forwarded to a stream that has been associated with this thread.
28 */
29 public class DemuxInputStream extends InputStream {
30
31 private final InheritableThreadLocal<InputStream> inputStreamLocal = new InheritableThreadLocal<>();
32
33 /**
34 * Construct a new instance.
35 */
36 public DemuxInputStream() {
37 // empty
38 }
39
40 /**
41 * Binds the specified stream to the current thread.
42 *
43 * @param input the stream to bind
44 * @return the InputStream that was previously active
45 */
46 public InputStream bindStream(final InputStream input) {
47 final InputStream oldValue = inputStreamLocal.get();
48 inputStreamLocal.set(input);
49 return oldValue;
50 }
51
52 /**
53 * Closes stream associated with current thread.
54 *
55 * @throws IOException 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(inputStreamLocal.get());
61 }
62
63 /**
64 * Reads byte from stream associated with current thread.
65 *
66 * @return the byte read from stream
67 * @throws IOException if an error occurs
68 */
69 @Override
70 public int read() throws IOException {
71 final InputStream inputStream = inputStreamLocal.get();
72 if (null != inputStream) {
73 return inputStream.read();
74 }
75 return EOF;
76 }
77 }