com.unboundid.util.AggregateInputStream Maven / Gradle / Ivy
/*
* Copyright 2011-2019 Ping Identity Corporation
* All Rights Reserved.
*/
/*
* Copyright (C) 2011-2019 Ping Identity Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License (GPLv2 only)
* or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see .
*/
package com.unboundid.util;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import static com.unboundid.util.UtilityMessages.*;
/**
* This class provides an input stream implementation that can aggregate
* multiple input streams. When reading data from this input stream, it will
* read from the first input stream until the end of it is reached, at point it
* will close it and start reading from the next one, and so on until all input
* streams have been exhausted. Closing the aggregate input stream will cause
* all remaining input streams to be closed.
*/
@ThreadSafety(level=ThreadSafetyLevel.NOT_THREADSAFE)
public final class AggregateInputStream
extends InputStream
{
// The currently-active input stream.
private volatile InputStream activeInputStream;
// The iterator that will be used to access the input streams.
private final Iterator streamIterator;
/**
* Creates a new aggregate input stream that will use the provided set of
* input streams.
*
* @param inputStreams The input streams to be used by this aggregate input
* stream. It must not be {@code null}.
*/
public AggregateInputStream(final InputStream... inputStreams)
{
this(StaticUtils.toList(inputStreams));
}
/**
* Creates a new aggregate input stream that will use the provided set of
* input streams.
*
* @param inputStreams The input streams to be used by this aggregate input
* stream. It must not be {@code null}.
*/
public AggregateInputStream(
final Collection inputStreams)
{
Validator.ensureNotNull(inputStreams);
final ArrayList streamList = new ArrayList<>(inputStreams);
streamIterator = streamList.iterator();
activeInputStream = null;
}
/**
* Creates a new aggregate input stream that will read data from the specified
* files.
*
* @param files The set of files to be read by this aggregate input stream.
* It must not be {@code null}.
*
* @throws IOException If a problem is encountered while attempting to
* create input streams for the provided files.
*/
public AggregateInputStream(final File... files)
throws IOException
{
this(false, files);
}
/**
* Creates a new aggregate input stream that will read data from the specified
* files.
*
* @param ensureBlankLinesBetweenFiles Indicates whether to ensure that
* there is at least one completely
* blank line between files. This may
* be useful when blank lines are
* used as delimiters (for example, when
* reading LDIF data), there is a chance
* that the files may not end with blank
* lines, and the inclusion of extra
* blank lines between files will not
* cause any harm.
* @param files The set of files to be read by this
* aggregate input stream. It must not
* be {@code null}.
*
* @throws IOException If a problem is encountered while attempting to
* create input streams for the provided files.
*/
public AggregateInputStream(final boolean ensureBlankLinesBetweenFiles,
final File... files)
throws IOException
{
Validator.ensureNotNull(files);
final ArrayList streamList = new ArrayList<>(2 * files.length);
IOException ioException = null;
for (final File f : files)
{
if (ensureBlankLinesBetweenFiles && (! streamList.isEmpty()))
{
final ByteStringBuffer buffer = new ByteStringBuffer(4);
buffer.append(StaticUtils.EOL_BYTES);
buffer.append(StaticUtils.EOL_BYTES);
streamList.add(new ByteArrayInputStream(buffer.toByteArray()));
}
try
{
streamList.add(new FileInputStream(f));
}
catch (final IOException ioe)
{
Debug.debugException(ioe);
ioException = ioe;
break;
}
}
if (ioException != null)
{
for (final InputStream s : streamList)
{
if (s != null)
{
try
{
s.close();
}
catch (final Exception e)
{
Debug.debugException(e);
}
}
}
throw ioException;
}
streamIterator = streamList.iterator();
activeInputStream = null;
}
/**
* Reads the next byte of data from the current active input stream, switching
* to the next input stream in the set if appropriate.
*
* @return The next byte of data that was read, or -1 if all streams have
* been exhausted.
*
* @throws IOException If a problem is encountered while attempting to read
* data from an input stream.
*/
@Override()
public int read()
throws IOException
{
while (true)
{
if (activeInputStream == null)
{
if (streamIterator.hasNext())
{
activeInputStream = streamIterator.next();
continue;
}
else
{
return -1;
}
}
final int byteRead = activeInputStream.read();
if (byteRead < 0)
{
activeInputStream.close();
activeInputStream = null;
}
else
{
return byteRead;
}
}
}
/**
* Reads data from the current active input stream into the provided array,
* switching to the next input stream in the set if appropriate.
*
* @param b The array into which the data read should be placed, starting
* with an index of zero. It must not be {@code null}.
*
* @return The number of bytes read into the array, or -1 if all streams have
* been exhausted.
*
* @throws IOException If a problem is encountered while attempting to read
* data from an input stream.
*/
@Override()
public int read(final byte[] b)
throws IOException
{
return read(b, 0, b.length);
}
/**
* Reads data from the current active input stream into the provided array,
* switching to the next input stream in the set if appropriate.
*
* @param b The array into which the data read should be placed. It must
* not be {@code null}.
* @param off The position in the array at which to start writing data.
* @param len The maximum number of bytes that may be read.
*
* @return The number of bytes read into the array, or -1 if all streams have
* been exhausted.
*
* @throws IOException If a problem is encountered while attempting to read
* data from an input stream.
*/
@Override()
public int read(final byte[] b, final int off, final int len)
throws IOException
{
while (true)
{
if (activeInputStream == null)
{
if (streamIterator.hasNext())
{
activeInputStream = streamIterator.next();
continue;
}
else
{
return -1;
}
}
final int bytesRead = activeInputStream.read(b, off, len);
if (bytesRead < 0)
{
activeInputStream.close();
activeInputStream = null;
}
else
{
return bytesRead;
}
}
}
/**
* Attempts to skip and discard up to the specified number of bytes from the
* input stream.
*
* @param n The number of bytes to attempt to skip.
*
* @return The number of bytes actually skipped.
*
* @throws IOException If a problem is encountered while attempting to skip
* data from the input stream.
*/
@Override()
public long skip(final long n)
throws IOException
{
if (activeInputStream == null)
{
if (streamIterator.hasNext())
{
activeInputStream = streamIterator.next();
return activeInputStream.skip(n);
}
else
{
return 0L;
}
}
else
{
return activeInputStream.skip(n);
}
}
/**
* Retrieves an estimate of the number of bytes that can be read without
* blocking.
*
* @return An estimate of the number of bytes that can be read without
* blocking.
*
* @throws IOException If a problem is encountered while attempting to make
* the determination.
*/
@Override()
public int available()
throws IOException
{
if (activeInputStream == null)
{
if (streamIterator.hasNext())
{
activeInputStream = streamIterator.next();
return activeInputStream.available();
}
else
{
return 0;
}
}
else
{
return activeInputStream.available();
}
}
/**
* Indicates whether this input stream supports the use of the {@code mark}
* and {@code reset} methods. This implementation does not support that
* capability.
*
* @return {@code false} to indicate that this input stream implementation
* does not support the use of {@code mark} and {@code reset}.
*/
@Override()
public boolean markSupported()
{
return false;
}
/**
* Marks the current position in the input stream. This input stream does not
* support this functionality, so no action will be taken.
*
* @param readLimit The maximum number of bytes that the caller may wish to
* read before being able to reset the stream.
*/
@Override()
public void mark(final int readLimit)
{
// No implementation is required.
}
/**
* Attempts to reset the position of this input stream to the mark location.
* This implementation does not support {@code mark} and {@code reset}
* functionality, so this method will always throw an exception.
*
* @throws IOException To indicate that reset is not supported.
*/
@Override()
public void reset()
throws IOException
{
throw new IOException(ERR_AGGREGATE_INPUT_STREAM_MARK_NOT_SUPPORTED.get());
}
/**
* Closes this input stream. All associated input streams will be closed.
*
* @throws IOException If an exception was encountered while attempting to
* close any of the associated streams. Note that even
* if an exception is encountered, an attempt will be
* made to close all streams.
*/
@Override()
public void close()
throws IOException
{
IOException firstException = null;
if (activeInputStream != null)
{
try
{
activeInputStream.close();
}
catch (final IOException ioe)
{
Debug.debugException(ioe);
firstException = ioe;
}
activeInputStream = null;
}
while (streamIterator.hasNext())
{
final InputStream s = streamIterator.next();
try
{
s.close();
}
catch (final IOException ioe)
{
Debug.debugException(ioe);
if (firstException == null)
{
firstException = ioe;
}
}
}
if (firstException != null)
{
throw firstException;
}
}
}