DemuxInputStream.java

  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. import static org.apache.commons.io.IOUtils.EOF;

  19. import java.io.IOException;
  20. import java.io.InputStream;

  21. import org.apache.commons.io.IOUtils;

  22. /**
  23.  * Data written to this stream is forwarded to a stream that has been associated with this thread.
  24.  */
  25. public class DemuxInputStream extends InputStream {

  26.     private final InheritableThreadLocal<InputStream> inputStreamLocal = new InheritableThreadLocal<>();

  27.     /**
  28.      * Construct a new instance.
  29.      */
  30.     public DemuxInputStream() {
  31.         // empty
  32.     }

  33.     /**
  34.      * Binds the specified stream to the current thread.
  35.      *
  36.      * @param input the stream to bind
  37.      * @return the InputStream that was previously active
  38.      */
  39.     public InputStream bindStream(final InputStream input) {
  40.         final InputStream oldValue = inputStreamLocal.get();
  41.         inputStreamLocal.set(input);
  42.         return oldValue;
  43.     }

  44.     /**
  45.      * Closes stream associated with current thread.
  46.      *
  47.      * @throws IOException if an error occurs
  48.      */
  49.     @SuppressWarnings("resource") // we actually close the stream here
  50.     @Override
  51.     public void close() throws IOException {
  52.         IOUtils.close(inputStreamLocal.get());
  53.     }

  54.     /**
  55.      * Reads byte from stream associated with current thread.
  56.      *
  57.      * @return the byte read from stream
  58.      * @throws IOException if an error occurs
  59.      */
  60.     @Override
  61.     public int read() throws IOException {
  62.         final InputStream inputStream = inputStreamLocal.get();
  63.         if (null != inputStream) {
  64.             return inputStream.read();
  65.         }
  66.         return EOF;
  67.     }
  68. }