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 07:39:07 +0100 (Mon, 28 Aug 2006) $ 28 */ 29 public class DemuxOutputStream 30 extends OutputStream 31 { 32 private InheritableThreadLocal<OutputStream> m_streams = new InheritableThreadLocal<OutputStream>(); 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 */ bindStream( OutputStream output )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 @Override close()53 public void close() 54 throws IOException 55 { 56 OutputStream output = getStream(); 57 if( null != output ) 58 { 59 output.close(); 60 } 61 } 62 63 /** 64 * Flushes stream associated with current thread. 65 * 66 * @throws IOException if an error occurs 67 */ 68 @Override flush()69 public void flush() 70 throws IOException 71 { 72 OutputStream output = getStream(); 73 if( null != output ) 74 { 75 output.flush(); 76 } 77 } 78 79 /** 80 * Writes byte to stream associated with current thread. 81 * 82 * @param ch the byte to write to stream 83 * @throws IOException if an error occurs 84 */ 85 @Override write( int ch )86 public void write( int ch ) 87 throws IOException 88 { 89 OutputStream output = getStream(); 90 if( null != output ) 91 { 92 output.write( ch ); 93 } 94 } 95 96 /** 97 * Utility method to retrieve stream bound to current thread (if any). 98 * 99 * @return the output stream 100 */ getStream()101 private OutputStream getStream() 102 { 103 return m_streams.get(); 104 } 105 } 106