    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.io.input;
    019
    020import java.io.IOException;
    021import java.io.InputStream;
    022import java.io.RandomAccessFile;
    023import java.util.Objects;
    024
    025/**
    026 * Streams data from a {@link RandomAccessFile} starting at its current position.
    027 *
    028 * @since 2.8.0
    029 */
    030public class RandomAccessFileInputStream extends InputStream {
    031
    032    private final boolean closeOnClose;
    033    private final RandomAccessFile randomAccessFile;
    034
    035    /**
    036     * Constructs a new instance configured to leave the underlying file open when this stream is closed.
    037     *
    038     * @param file The file to stream.
    039     */
    040    public RandomAccessFileInputStream(final RandomAccessFile file) {
    041        this(file, false);
    042    }
    043
    044    /**
    045     * Constructs a new instance.
    046     *
    047     * @param file The file to stream.
    048     * @param closeOnClose Whether to close the underlying file when this stream is closed.
    049     */
    050    public RandomAccessFileInputStream(final RandomAccessFile file, final boolean closeOnClose) {
    051        this.randomAccessFile = Objects.requireNonNull(file, "file");
    052        this.closeOnClose = closeOnClose;
    053    }
    054
    055    /**
    056     * Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream.
    057     *
    058     * If there are more than {@link Integer#MAX_VALUE} bytes available, return {@link Integer#MAX_VALUE}.
    059     *
    060     * @return An estimate of the number of bytes that can be read.
    061     * @throws IOException If an I/O error occurs.
    062     */
    063    @Override
    064    public int available() throws IOException {
    065        final long avail = availableLong();
    066        if (avail > Integer.MAX_VALUE) {
    067            return Integer.MAX_VALUE;
    068        }
    069        return (int) avail;
    070    }
    071
    072    /**
    073     * Returns the number of bytes that can be read (or skipped over) from this input stream.
    074     *
    075     * @return The number of bytes that can be read.
    076     * @throws IOException If an I/O error occurs.
    077     */
    078    public long availableLong() throws IOException {
    079        return randomAccessFile.length() - randomAccessFile.getFilePointer();
    080    }
    081
    082    @Override
    083    public void close() throws IOException {
    084        super.close();
    085        if (closeOnClose) {
    086            randomAccessFile.close();
    087        }
    088    }
    089
    090    /**
    091     * Gets the underlying file.
    092     *
    093     * @return the underlying file.
    094     */
    095    public RandomAccessFile getRandomAccessFile() {
    096        return randomAccessFile;
    097    }
    098
    099    /**
    100     * Returns whether to close the underlying file when this stream is closed.
    101     *
    102     * @return Whether to close the underlying file when this stream is closed.
    103     */
    104    public boolean isCloseOnClose() {
    105        return closeOnClose;
    106    }
    107
    108    @Override
    109    public int read() throws IOException {
    110        return randomAccessFile.read();
    111    }
    112
    113    @Override
    114    public int read(final byte[] bytes) throws IOException {
    115        return randomAccessFile.read(bytes);
    116    }
    117
    118    @Override
    119    public int read(final byte[] bytes, final int offset, final int length) throws IOException {
    120        return randomAccessFile.read(bytes, offset, length);
    121    }
    122
    123    /**
    124     * Delegates to the underlying file.
    125     *
    126     * @param position See {@link RandomAccessFile#seek(long)}.
    127     * @throws IOException See {@link RandomAccessFile#seek(long)}.
    128     * @see RandomAccessFile#seek(long)
    129     */
    130    private void seek(final long position) throws IOException {
    131        randomAccessFile.seek(position);
    132    }
    133
    134    @Override
    135    public long skip(final long skipCount) throws IOException {
    136        if (skipCount <= 0) {
    137            return 0;
    138        }
    139        final long filePointer = randomAccessFile.getFilePointer();
    140        final long fileLength = randomAccessFile.length();
    141        if (filePointer >= fileLength) {
    142            return 0;
    143        }
    144        final long targetPos = filePointer + skipCount;
    145        final long newPos = targetPos > fileLength ? fileLength - 1 : targetPos;
    146        if (newPos > 0) {
    147            seek(newPos);
    148        }
    149        return randomAccessFile.getFilePointer() - filePointer;
    150    }
    151}