- /*
- * $Header: /home/cvs/jakarta-commons/fileupload/src/java/org/apache/commons/fileupload/DeferredFileOutputStream.java,v 1.2 2003/05/31 22:31:08 martinc Exp $
- * $Revision: 1.2 $
- * $Date: 2003/05/31 22:31:08 $
- *
- * ====================================================================
- *
- * The Apache Software License, Version 1.1
- *
- * Copyright (c) 2001-2003 The Apache Software Foundation. All rights
- * reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * 3. The end-user documentation included with the redistribution, if
- * any, must include the following acknowlegement:
- * "This product includes software developed by the
- * Apache Software Foundation (http://www.apache.org/)."
- * Alternately, this acknowlegement may appear in the software itself,
- * if and wherever such third-party acknowlegements normally appear.
- *
- * 4. The names "The Jakarta Project", "Commons", and "Apache Software
- * Foundation" must not be used to endorse or promote products derived
- * from this software without prior written permission. For written
- * permission, please contact apache@apache.org.
- *
- * 5. Products derived from this software may not be called "Apache"
- * nor may "Apache" appear in their names without prior written
- * permission of the Apache Group.
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * ====================================================================
- *
- * This software consists of voluntary contributions made by many
- * individuals on behalf of the Apache Software Foundation. For more
- * information on the Apache Software Foundation, please see
- * <http://www.apache.org/>.
- *
- */
-
-
- package org.apache.commons.fileupload;
-
- import java.io.ByteArrayOutputStream;
- import java.io.File;
- import java.io.FileOutputStream;
- import java.io.IOException;
- import java.io.OutputStream;
-
- /**
- * <p>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.</p>
- *
- * @author <a href="mailto:martinc@apache.org">Martin Cooper</a>
- *
- * @version $Id: DeferredFileOutputStream.java,v 1.2 2003/05/31 22:31:08 martinc Exp $
- */
- public class DeferredFileOutputStream
- extends ThresholdingOutputStream
- {
-
- // ----------------------------------------------------------- Data members
-
-
- /**
- * The output stream to which data will be written prior to the theshold
- * being reached.
- */
- private ByteArrayOutputStream memoryOutputStream;
-
-
- /**
- * The output stream to which data will be written after the theshold is
- * reached.
- */
- private FileOutputStream diskOutputStream;
-
-
- /**
- * The output stream to which data will be written at any given time. This
- * will always be one of <code>memoryOutputStream</code> or
- * <code>diskOutputStream</code>.
- */
- private OutputStream currentOutputStream;
-
-
- /**
- * The file to which output will be directed if the threshold is exceeded.
- */
- private File outputFile;
-
-
- // ----------------------------------------------------------- Constructors
-
-
- /**
- * 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 outputFile The file to which data is saved beyond the threshold.
- */
- public DeferredFileOutputStream(int threshold, File outputFile)
- {
- super(threshold);
- this.outputFile = outputFile;
-
- memoryOutputStream = new ByteArrayOutputStream(threshold);
- currentOutputStream = memoryOutputStream;
- }
-
-
- // --------------------------------------- ThresholdingOutputStream methods
-
-
- /**
- * 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.
- *
- * @exception IOException if an error occurs.
- */
- protected OutputStream getStream() throws IOException
- {
- return currentOutputStream;
- }
-
-
- /**
- * Switches the underlying output stream from a memory based stream to one
- * that is backed by disk. This is the point at which we realise that too
- * much data is being written to keep in memory, so we elect to switch to
- * disk-based storage.
- *
- * @exception IOException if an error occurs.
- */
- protected void thresholdReached() throws IOException
- {
- byte[] data = memoryOutputStream.toByteArray();
- FileOutputStream fos = new FileOutputStream(outputFile);
- fos.write(data);
- diskOutputStream = fos;
- currentOutputStream = fos;
- memoryOutputStream = null;
- }
-
-
- // --------------------------------------------------------- Public methods
-
-
- /**
- * Determines whether or not the data for this output stream has been
- * retained in memory.
- *
- * @return <code>true</code> if the data is available in memory;
- * <code>false</code> otherwise.
- */
- public boolean isInMemory()
- {
- return (!isThresholdExceeded());
- }
-
-
- /**
- * 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</code>.
- *
- * @return The data for this output stream, or <code>null</code> if no such
- * data is available.
- */
- public byte[] getData()
- {
- if (memoryOutputStream != null)
- {
- return memoryOutputStream.toByteArray();
- }
- return null;
- }
-
-
- /**
- * Returns the data for this output stream as a <code>File</code>, assuming
- * that the data was written to disk. If the data was retained in memory,
- * this method returns <code>null</code>.
- *
- * @return The file for this output stream, or <code>null</code> if no such
- * file exists.
- */
- public File getFile()
- {
- return outputFile;
- }
- }