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 */
17package org.apache.commons.io.input;
18
19import java.io.IOException;
20import java.io.InputStream;
21
22/**
23 * Data written to this stream is forwarded to a stream that has been associated
24 * with this thread.
25 *
26 * @author <a href="mailto:peter@apache.org">Peter Donald</a>
27 * @version $Revision: 437567 $ $Date: 2006-08-28 07:39:07 +0100 (Mon, 28 Aug 2006) $
28 */
29public class DemuxInputStream
30    extends InputStream
31{
32    private InheritableThreadLocal m_streams = new InheritableThreadLocal();
33
34    /**
35     * Bind the specified stream to the current thread.
36     *
37     * @param input the stream to bind
38     * @return the InputStream that was previously active
39     */
40    public InputStream bindStream( InputStream input )
41    {
42        InputStream oldValue = getStream();
43        m_streams.set( input );
44        return oldValue;
45    }
46
47    /**
48     * Closes stream associated with current thread.
49     *
50     * @throws IOException if an error occurs
51     */
52    public void close()
53        throws IOException
54    {
55        InputStream input = getStream();
56        if( null != input )
57        {
58            input.close();
59        }
60    }
61
62    /**
63     * Read byte from stream associated with current thread.
64     *
65     * @return the byte read from stream
66     * @throws IOException if an error occurs
67     */
68    public int read()
69        throws IOException
70    {
71        InputStream input = getStream();
72        if( null != input )
73        {
74            return input.read();
75        }
76        else
77        {
78            return -1;
79        }
80    }
81
82    /**
83     * Utility method to retrieve stream bound to current thread (if any).
84     *
85     * @return the input stream
86     */
87    private InputStream getStream()
88    {
89        return (InputStream)m_streams.get();
90    }
91}
92