001/**
002 * Copyright 2015 DuraSpace, Inc.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.fcrepo.http.commons.responses;
017
018import java.io.FilterInputStream;
019import java.io.IOException;
020import java.io.InputStream;
021
022import org.apache.commons.io.IOUtils;
023import org.apache.commons.io.input.BoundedInputStream;
024import org.apache.commons.io.input.ProxyInputStream;
025
026/**
027 * An InputStream wrapper that skips N bytes and only returns
028 * the data up to a certain length
029 *
030 * @author awoods
031 */
032public class RangeRequestInputStream extends FilterInputStream {
033
034    /**
035     * Creates a <code>FilterInputStream</code>
036     * by assigning the  argument <code>in</code>
037     * to the field <code>this.in</code> so as
038     * to remember it for later use.
039     *
040     * @param in the underlying input stream, or <code>null</code> if
041     *           this instance is to be created without an underlying stream.
042     * @param skip the number of bytes to skip at the beginning of the stream
043     * @param length the number of bytes from the inputstream to read
044     * @throws IOException if IO exception occurred
045     */
046    public RangeRequestInputStream(final InputStream in,
047                                   final long skip,
048                                   final long length) throws IOException {
049        super(new BoundedInputStream(new SkipInputStream(in, skip), length));
050    }
051
052
053    /**
054     * An InputStream wrapper that skips bytes
055     * @param in
056     * @param skip
057     * @throws IOException
058     */
059    private static class SkipInputStream extends ProxyInputStream {
060
061        /**
062         * An InputStream wrapper that always skips the first N bytes
063         * @param in
064         * @param skip
065         * @throws IOException
066         */
067        public SkipInputStream(final InputStream in,
068                               final long skip) throws IOException {
069            super(in);
070            IOUtils.skip(in, skip);
071        }
072    }
073}