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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.io.output;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
/**
* An output stream which will retain data in memory until a specified threshold is reached, and only then commit it to
* disk. If the stream is closed before the threshold is reached, the data will not be written to disk at all.
*
* This class originated in FileUpload processing. In this use case, you do not know in advance the size of the file
* being uploaded. If the file is small you want to store it in memory (for speed), but if the file is large you want to
* store it to file (to avoid memory issues).
*
*/
public class DeferredFileOutputStream extends ThresholdingOutputStream {
/**
* The output stream to which data will be written prior to the threshold being reached.
*/
private ByteArrayOutputStream memoryOutputStream;
/**
* The output stream to which data will be written at any given time. This will always be one of
* {@code memoryOutputStream} or {@code diskOutputStream}.
*/
private OutputStream currentOutputStream;
/**
* The file to which output will be directed if the threshold is exceeded.
*/
private File outputFile;
/**
* The temporary file prefix.
*/
private final String prefix;
/**
* The temporary file suffix.
*/
private final String suffix;
/**
* The directory to use for temporary files.
*/
private final File directory;
/**
* True when close() has been called successfully.
*/
private boolean closed;
/**
* Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a
* file beyond that point. The initial buffer size will default to
* {@value AbstractByteArrayOutputStream#DEFAULT_SIZE} bytes which is ByteArrayOutputStream's default buffer size.
*
* @param threshold The number of bytes at which to trigger an event.
* @param outputFile The file to which data is saved beyond the threshold.
*/
public DeferredFileOutputStream(final int threshold, final File outputFile) {
this(threshold, outputFile, null, null, null, AbstractByteArrayOutputStream.DEFAULT_SIZE);
}
/**
* Constructs an instance of this class which will trigger an event at the specified threshold, and save data either
* to a file beyond that point.
*
* @param threshold The number of bytes at which to trigger an event.
* @param outputFile The file to which data is saved beyond the threshold.
* @param prefix Prefix to use for the temporary file.
* @param suffix Suffix to use for the temporary file.
* @param directory Temporary file directory.
* @param initialBufferSize The initial size of the in memory buffer.
*/
private DeferredFileOutputStream(final int threshold, final File outputFile, final String prefix,
final String suffix, final File directory, final int initialBufferSize) {
super(threshold);
this.outputFile = outputFile;
this.prefix = prefix;
this.suffix = suffix;
this.directory = directory;
memoryOutputStream = new ByteArrayOutputStream(initialBufferSize);
currentOutputStream = memoryOutputStream;
}
/**
* Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a
* file beyond that point.
*
* @param threshold The number of bytes at which to trigger an event.
* @param initialBufferSize The initial size of the in memory buffer.
* @param outputFile The file to which data is saved beyond the threshold.
*
* @since 2.5
*/
public DeferredFileOutputStream(final int threshold, final int initialBufferSize, final File outputFile) {
this(threshold, outputFile, null, null, null, initialBufferSize);
if (initialBufferSize < 0) {
throw new IllegalArgumentException("Initial buffer size must be atleast 0.");
}
}
/**
* Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a
* temporary file beyond that point.
*
* @param threshold The number of bytes at which to trigger an event.
* @param initialBufferSize The initial size of the in memory buffer.
* @param prefix Prefix to use for the temporary file.
* @param suffix Suffix to use for the temporary file.
* @param directory Temporary file directory.
*
* @since 2.5
*/
public DeferredFileOutputStream(final int threshold, final int initialBufferSize, final String prefix,
final String suffix, final File directory) {
this(threshold, null, prefix, suffix, directory, initialBufferSize);
if (prefix == null) {
throw new IllegalArgumentException("Temporary file prefix is missing");
}
if (initialBufferSize < 0) {
throw new IllegalArgumentException("Initial buffer size must be atleast 0.");
}
}
/**
* Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a
* temporary file beyond that point. The initial buffer size will default to 32 bytes which is
* ByteArrayOutputStream's default buffer size.
*
* @param threshold The number of bytes at which to trigger an event.
* @param prefix Prefix to use for the temporary file.
* @param suffix Suffix to use for the temporary file.
* @param directory Temporary file directory.
*
* @since 1.4
*/
public DeferredFileOutputStream(final int threshold, final String prefix, final String suffix,
final File directory) {
this(threshold, null, prefix, suffix, directory, AbstractByteArrayOutputStream.DEFAULT_SIZE);
if (prefix == null) {
throw new IllegalArgumentException("Temporary file prefix is missing");
}
}
/**
* Closes underlying output stream, and mark this as closed
*
* @throws IOException if an error occurs.
*/
@Override
public void close() throws IOException {
super.close();
closed = true;
}
/**
* Returns the data for this output stream as an array of bytes, assuming that the data has been retained in memory.
* If the data was written to disk, this method returns {@code null}.
*
* @return The data for this output stream, or {@code null} if no such data is available.
*/
public byte[] getData() {
return memoryOutputStream != null ? memoryOutputStream.toByteArray() : null;
}
/**
* Returns either the output file specified in the constructor or the temporary file created or null.
*
* If the constructor specifying the file is used then it returns that same output file, even when threshold has not
* been reached.
*
* If constructor specifying a temporary file prefix/suffix is used then the temporary file created once the
* threshold is reached is returned If the threshold was not reached then {@code null} is returned.
*
* @return The file for this output stream, or {@code null} if no such file exists.
*/
public File getFile() {
return outputFile;
}
/**
* Returns the current output stream. This may be memory based or disk based, depending on the current state with
* respect to the threshold.
*
* @return The underlying output stream.
*
* @throws IOException if an error occurs.
*/
@Override
protected OutputStream getStream() throws IOException {
return currentOutputStream;
}
/**
* Determines whether or not the data for this output stream has been retained in memory.
*
* @return {@code true} if the data is available in memory; {@code false} otherwise.
*/
public boolean isInMemory() {
return !isThresholdExceeded();
}
/**
* Switches the underlying output stream from a memory based stream to one that is backed by disk. This is the point
* at which we realize that too much data is being written to keep in memory, so we elect to switch to disk-based
* storage.
*
* @throws IOException if an error occurs.
*/
@Override
protected void thresholdReached() throws IOException {
if (prefix != null) {
outputFile = File.createTempFile(prefix, suffix, directory);
}
FileUtils.forceMkdirParent(outputFile);
final OutputStream fos = Files.newOutputStream(outputFile.toPath());
try {
memoryOutputStream.writeTo(fos);
} catch (final IOException e) {
fos.close();
throw e;
}
currentOutputStream = fos;
memoryOutputStream = null;
}
/**
* Gets the current contents of this byte stream as an {@link InputStream}.
* If the data for this output stream has been retained in memory, the
* returned stream is backed by buffers of {@code this} stream,
* avoiding memory allocation and copy, thus saving space and time.
* Otherwise, the returned stream will be one that is created from the data
* that has been committed to disk.
*
* @return the current contents of this output stream.
* @throws IOException if this stream is not yet closed or an error occurs.
* @see org.apache.commons.io.output.ByteArrayOutputStream#toInputStream()
*
* @since 2.9.0
*/
public InputStream toInputStream() throws IOException {
// we may only need to check if this is closed if we are working with a file
// but we should force the habit of closing whether we are working with
// a file or memory.
if (!closed) {
throw new IOException("Stream not closed");
}
if (isInMemory()) {
return memoryOutputStream.toInputStream();
}
return Files.newInputStream(outputFile.toPath());
}
/**
* Writes the data from this output stream to the specified output stream, after it has been closed.
*
* @param outputStream output stream to write to.
* @throws NullPointerException if the OutputStream is {@code null}.
* @throws IOException if this stream is not yet closed or an error occurs.
*/
public void writeTo(final OutputStream outputStream) throws IOException {
// we may only need to check if this is closed if we are working with a file
// but we should force the habit of closing whether we are working with
// a file or memory.
if (!closed) {
throw new IOException("Stream not closed");
}
if (isInMemory()) {
memoryOutputStream.writeTo(outputStream);
} else {
try (InputStream fis = Files.newInputStream(outputFile.toPath())) {
IOUtils.copy(fis, outputStream);
}
}
}
}