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Add ThresholdingOutputStream and DeferredFileOutputStream, along with tests
for the latter. (There are no tests for the former, since it is an abstract class.) These classes originated in Commons FileUpload (and will continue to exist there as well, until IO gets to an official release). git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/io/trunk@140496 13f79535-47bb-0310-9956-ffa450edef68
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‎project.xml‎

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</roles>
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</developer>
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<developer>
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<name>Martin Cooper</name>
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<id>martinc</id>
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<email>martinc@apache.org</email>
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<organization/>
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<roles>
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<role>Java Developer</role>
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</roles>
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</developer>
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</developers>
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<contributors>

‎src/java/org/apache/commons/io/output/DeferredFileOutputStream.java‎

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/*
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* $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//io/src/java/org/apache/commons/io/output/DeferredFileOutputStream.java,v 1.1 2004/02/01 07:37:36 martinc Exp $
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* $Revision: 1.1 $
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* $Date: 2004/02/01 07:37:36 $
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*
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* ====================================================================
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*
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* The Apache Software License, Version 1.1
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*
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* Copyright (c) 2001-2003 The Apache Software Foundation. All rights
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* reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. The end-user documentation included with the redistribution, if
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* any, must include the following acknowledgement:
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* "This product includes software developed by the
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* Apache Software Foundation (http://www.apache.org/)."
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* Alternately, this acknowledgement may appear in the software itself,
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* if and wherever such third-party acknowledgements normally appear.
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*
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* 4. The names "The Jakarta Project", "Commons", and "Apache Software
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* Foundation" must not be used to endorse or promote products derived
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* from this software without prior written permission. For written
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* permission, please contact apache@apache.org.
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*
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* 5. Products derived from this software may not be called "Apache"
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* nor may "Apache" appear in their names without prior written
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* permission of the Apache Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*
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*/
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package org.apache.commons.io.output;
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import java.io.ByteArrayOutputStream;
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import java.io.File;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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/**
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* <p>An output stream which will retain data in memory until a specified
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* threshold is reached, and only then commit it to disk. If the stream is
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* closed before the threshold is reached, the data will not be written to
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* disk at all.</p>
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*
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* @author <a href="mailto:martinc@apache.org">Martin Cooper</a>
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*
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* @version $Id: DeferredFileOutputStream.java,v 1.1 2004/02/01 07:37:36 martinc Exp $
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*/
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public class DeferredFileOutputStream
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extends ThresholdingOutputStream
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{
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// ----------------------------------------------------------- Data members
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/**
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* The output stream to which data will be written prior to the theshold
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* being reached.
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*/
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private ByteArrayOutputStream memoryOutputStream;
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/**
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* The output stream to which data will be written after the theshold is
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* reached.
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*/
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private FileOutputStream diskOutputStream;
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/**
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* The output stream to which data will be written at any given time. This
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* will always be one of <code>memoryOutputStream</code> or
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* <code>diskOutputStream</code>.
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*/
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private OutputStream currentOutputStream;
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/**
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* The file to which output will be directed if the threshold is exceeded.
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*/
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private File outputFile;
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// ----------------------------------------------------------- Constructors
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/**
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* Constructs an instance of this class which will trigger an event at the
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* specified threshold, and save data to a file beyond that point.
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*
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* @param threshold The number of bytes at which to trigger an event.
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* @param outputFile The file to which data is saved beyond the threshold.
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*/
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public DeferredFileOutputStream(int threshold, File outputFile)
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{
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super(threshold);
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this.outputFile = outputFile;
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memoryOutputStream = new ByteArrayOutputStream(threshold);
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currentOutputStream = memoryOutputStream;
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}
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// --------------------------------------- ThresholdingOutputStream methods
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/**
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* Returns the current output stream. This may be memory based or disk
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* based, depending on the current state with respect to the threshold.
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*
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* @return The underlying output stream.
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*
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* @exception IOException if an error occurs.
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*/
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protected OutputStream getStream() throws IOException
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{
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return currentOutputStream;
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}
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/**
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* Switches the underlying output stream from a memory based stream to one
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* that is backed by disk. This is the point at which we realise that too
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* much data is being written to keep in memory, so we elect to switch to
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* disk-based storage.
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*
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* @exception IOException if an error occurs.
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*/
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protected void thresholdReached() throws IOException
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{
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byte[] data = memoryOutputStream.toByteArray();
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FileOutputStream fos = new FileOutputStream(outputFile);
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fos.write(data);
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diskOutputStream = fos;
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currentOutputStream = fos;
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memoryOutputStream = null;
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}
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// --------------------------------------------------------- Public methods
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/**
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* Determines whether or not the data for this output stream has been
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* retained in memory.
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*
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* @return <code>true</code> if the data is available in memory;
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* <code>false</code> otherwise.
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*/
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public boolean isInMemory()
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{
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return (!isThresholdExceeded());
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}
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/**
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* Returns the data for this output stream as an array of bytes, assuming
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* that the data has been retained in memory. If the data was written to
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* disk, this method returns <code>null</code>.
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*
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* @return The data for this output stream, or <code>null</code> if no such
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* data is available.
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*/
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public byte[] getData()
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{
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if (memoryOutputStream != null)
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{
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return memoryOutputStream.toByteArray();
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}
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return null;
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}
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/**
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* Returns the data for this output stream as a <code>File</code>, assuming
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* that the data was written to disk. If the data was retained in memory,
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* this method returns <code>null</code>.
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*
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* @return The file for this output stream, or <code>null</code> if no such
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* file exists.
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*/
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public File getFile()
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{
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return outputFile;
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}
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}

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