001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.io.output; 018 019import java.io.IOException; 020import java.io.OutputStream; 021 022import org.apache.commons.io.IOUtils; 023 024/** 025 * Forwards data to a stream that has been associated with this thread. 026 * 027 */ 028public class DemuxOutputStream extends OutputStream { 029 private final InheritableThreadLocal<OutputStream> outputStreamThreadLocal = new InheritableThreadLocal<>(); 030 031 /** 032 * Binds the specified stream to the current thread. 033 * 034 * @param output 035 * the stream to bind 036 * @return the OutputStream that was previously active 037 */ 038 public OutputStream bindStream(final OutputStream output) { 039 final OutputStream stream = outputStreamThreadLocal.get(); 040 outputStreamThreadLocal.set(output); 041 return stream; 042 } 043 044 /** 045 * Closes stream associated with current thread. 046 * 047 * @throws IOException 048 * if an error occurs 049 */ 050 @SuppressWarnings("resource") // we actually close the stream here 051 @Override 052 public void close() throws IOException { 053 IOUtils.close(outputStreamThreadLocal.get()); 054 } 055 056 /** 057 * Flushes stream associated with current thread. 058 * 059 * @throws IOException 060 * if an error occurs 061 */ 062 @Override 063 public void flush() throws IOException { 064 @SuppressWarnings("resource") 065 final OutputStream output = outputStreamThreadLocal.get(); 066 if (null != output) { 067 output.flush(); 068 } 069 } 070 071 /** 072 * Writes byte to stream associated with current thread. 073 * 074 * @param ch 075 * the byte to write to stream 076 * @throws IOException 077 * if an error occurs 078 */ 079 @Override 080 public void write(final int ch) throws IOException { 081 @SuppressWarnings("resource") 082 final OutputStream output = outputStreamThreadLocal.get(); 083 if (null != output) { 084 output.write(ch); 085 } 086 } 087}