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 org.apache.commons.io.input.QueueInputStream; 020 021import java.io.InterruptedIOException; 022import java.io.OutputStream; 023import java.io.PipedInputStream; 024import java.io.PipedOutputStream; 025import java.util.Objects; 026import java.util.concurrent.BlockingQueue; 027import java.util.concurrent.LinkedBlockingQueue; 028 029/** 030 * Simple alternative to JDK {@link java.io.PipedOutputStream}; queue input stream provides what's written in queue 031 * output stream. 032 * <p> 033 * Example usage: 034 * </p> 035 * 036 * <pre> 037 * QueueOutputStream outputStream = new QueueOutputStream(); 038 * QueueInputStream inputStream = outputStream.newPipeInputStream(); 039 * 040 * outputStream.write("hello world".getBytes(UTF_8)); 041 * inputStream.read(); 042 * </pre> 043 * 044 * Unlike JDK {@link PipedInputStream} and {@link PipedOutputStream}, queue input/output streams may be used safely in a 045 * single thread or multiple threads. Also, unlike JDK classes, no special meaning is attached to initial or current 046 * thread. Instances can be used longer after initial threads exited. 047 * <p> 048 * Closing a {@code QueueOutputStream} has no effect. The methods in this class can be called after the stream has been 049 * closed without generating an {@code IOException}. 050 * </p> 051 * 052 * @see QueueInputStream 053 * @since 2.9.0 054 */ 055public class QueueOutputStream extends OutputStream { 056 057 private final BlockingQueue<Integer> blockingQueue; 058 059 /** 060 * Constructs a new instance with no limit to internal buffer size. 061 */ 062 public QueueOutputStream() { 063 this(new LinkedBlockingQueue<>()); 064 } 065 066 /** 067 * Constructs a new instance with given buffer. 068 * 069 * @param blockingQueue backing queue for the stream 070 */ 071 public QueueOutputStream(final BlockingQueue<Integer> blockingQueue) { 072 this.blockingQueue = Objects.requireNonNull(blockingQueue, "blockingQueue"); 073 } 074 075 /** 076 * Creates a new QueueInputStream instance connected to this. Writes to this output stream will be visible to the 077 * input stream. 078 * 079 * @return QueueInputStream connected to this stream 080 */ 081 public QueueInputStream newQueueInputStream() { 082 return new QueueInputStream(blockingQueue); 083 } 084 085 /** 086 * Writes a single byte. 087 * 088 * @throws InterruptedIOException if the thread is interrupted while writing to the queue. 089 */ 090 @Override 091 public void write(final int b) throws InterruptedIOException { 092 try { 093 blockingQueue.put(0xFF & b); 094 } catch (final InterruptedException e) { 095 Thread.currentThread().interrupt(); 096 final InterruptedIOException interruptedIoException = new InterruptedIOException(); 097 interruptedIoException.initCause(e); 098 throw interruptedIoException; 099 } 100 } 101}