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 /**
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 08:39:07 +0200 (Mo, 28 Aug 2006) $
28 */
29 public class DemuxOutputStream
30 extends OutputStream
31 {
32 private InheritableThreadLocal m_streams = new InheritableThreadLocal();
33
34 /**
35 * Bind the specified stream to the current thread.
36 *
37 * @param output the stream to bind
38 * @return the OutputStream that was previously active
39 */
40 public OutputStream bindStream( OutputStream output )
41 {
42 OutputStream stream = getStream();
43 m_streams.set( output );
44 return stream;
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 OutputStream output = getStream();
56 if( null != output )
57 {
58 output.close();
59 }
60 }
61
62 /**
63 * Flushes stream associated with current thread.
64 *
65 * @throws IOException if an error occurs
66 */
67 public void flush()
68 throws IOException
69 {
70 OutputStream output = getStream();
71 if( null != output )
72 {
73 output.flush();
74 }
75 }
76
77 /**
78 * Writes byte to stream associated with current thread.
79 *
80 * @param ch the byte to write to stream
81 * @throws IOException if an error occurs
82 */
83 public void write( int ch )
84 throws IOException
85 {
86 OutputStream output = getStream();
87 if( null != output )
88 {
89 output.write( ch );
90 }
91 }
92
93 /**
94 * Utility method to retrieve stream bound to current thread (if any).
95 *
96 * @return the output stream
97 */
98 private OutputStream getStream()
99 {
100 return (OutputStream)m_streams.get();
101 }
102 }