    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     */
    018    package org.apache.commons.compress.archivers.zip;
    019
    020    /**
    021     * Utility class that represents a two byte integer with conversion
    022     * rules for the big endian byte order of ZIP files.
    023     * @Immutable
    024     */
    025    public final class ZipShort implements Cloneable {
    026        private static final int BYTE_MASK = 0xFF;
    027        private static final int BYTE_1_MASK = 0xFF00;
    028        private static final int BYTE_1_SHIFT = 8;
    029
    030        private final int value;
    031
    032        /**
    033         * Create instance from a number.
    034         * @param value the int to store as a ZipShort
    035         */
    036        public ZipShort (int value) {
    037            this.value = value;
    038        }
    039
    040        /**
    041         * Create instance from bytes.
    042         * @param bytes the bytes to store as a ZipShort
    043         */
    044        public ZipShort (byte[] bytes) {
    045            this(bytes, 0);
    046        }
    047
    048        /**
    049         * Create instance from the two bytes starting at offset.
    050         * @param bytes the bytes to store as a ZipShort
    051         * @param offset the offset to start
    052         */
    053        public ZipShort (byte[] bytes, int offset) {
    054            value = ZipShort.getValue(bytes, offset);
    055        }
    056
    057        /**
    058         * Get value as two bytes in big endian byte order.
    059         * @return the value as a a two byte array in big endian byte order
    060         */
    061        public byte[] getBytes() {
    062            byte[] result = new byte[2];
    063            result[0] = (byte) (value & BYTE_MASK);
    064            result[1] = (byte) ((value & BYTE_1_MASK) >> BYTE_1_SHIFT);
    065            return result;
    066        }
    067
    068        /**
    069         * Get value as Java int.
    070         * @return value as a Java int
    071         */
    072        public int getValue() {
    073            return value;
    074        }
    075
    076        /**
    077         * Get value as two bytes in big endian byte order.
    078         * @param value the Java int to convert to bytes
    079         * @return the converted int as a byte array in big endian byte order
    080         */
    081        public static byte[] getBytes(int value) {
    082            byte[] result = new byte[2];
    083            result[0] = (byte) (value & BYTE_MASK);
    084            result[1] = (byte) ((value & BYTE_1_MASK) >> BYTE_1_SHIFT);
    085            return result;
    086        }
    087
    088        /**
    089         * Helper method to get the value as a java int from two bytes starting at given array offset
    090         * @param bytes the array of bytes
    091         * @param offset the offset to start
    092         * @return the correspondanding java int value
    093         */
    094        public static int getValue(byte[] bytes, int offset) {
    095            int value = (bytes[offset + 1] << BYTE_1_SHIFT) & BYTE_1_MASK;
    096            value += (bytes[offset] & BYTE_MASK);
    097            return value;
    098        }
    099
    100        /**
    101         * Helper method to get the value as a java int from a two-byte array
    102         * @param bytes the array of bytes
    103         * @return the correspondanding java int value
    104         */
    105        public static int getValue(byte[] bytes) {
    106            return getValue(bytes, 0);
    107        }
    108
    109        /**
    110         * Override to make two instances with same value equal.
    111         * @param o an object to compare
    112         * @return true if the objects are equal
    113         */
    114        public boolean equals(Object o) {
    115            if (o == null || !(o instanceof ZipShort)) {
    116                return false;
    117            }
    118            return value == ((ZipShort) o).getValue();
    119        }
    120
    121        /**
    122         * Override to make two instances with same value equal.
    123         * @return the value stored in the ZipShort
    124         */
    125        public int hashCode() {
    126            return value;
    127        }
    128
    129        public Object clone() {
    130            try {
    131                return super.clone();
    132            } catch (CloneNotSupportedException cnfe) {
    133                // impossible
    134                throw new RuntimeException(cnfe);
    135            }
    136        }
    137    }