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    }