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    import static org.apache.commons.compress.archivers.zip.ZipConstants.BYTE_MASK;
021    
022    /**
023     * Utility class that represents a two byte integer with conversion
024     * rules for the big endian byte order of ZIP files.
025     * @Immutable
026     */
027    public final class ZipShort implements Cloneable {
028        private static final int BYTE_1_MASK = 0xFF00;
029        private static final int BYTE_1_SHIFT = 8;
030    
031        private final int value;
032    
033        /**
034         * Create instance from a number.
035         * @param value the int to store as a ZipShort
036         */
037        public ZipShort (int value) {
038            this.value = value;
039        }
040    
041        /**
042         * Create instance from bytes.
043         * @param bytes the bytes to store as a ZipShort
044         */
045        public ZipShort (byte[] bytes) {
046            this(bytes, 0);
047        }
048    
049        /**
050         * Create instance from the two bytes starting at offset.
051         * @param bytes the bytes to store as a ZipShort
052         * @param offset the offset to start
053         */
054        public ZipShort (byte[] bytes, int offset) {
055            value = ZipShort.getValue(bytes, offset);
056        }
057    
058        /**
059         * Get value as two bytes in big endian byte order.
060         * @return the value as a a two byte array in big endian byte order
061         */
062        public byte[] getBytes() {
063            byte[] result = new byte[2];
064            result[0] = (byte) (value & BYTE_MASK);
065            result[1] = (byte) ((value & BYTE_1_MASK) >> BYTE_1_SHIFT);
066            return result;
067        }
068    
069        /**
070         * Get value as Java int.
071         * @return value as a Java int
072         */
073        public int getValue() {
074            return value;
075        }
076    
077        /**
078         * Get value as two bytes in big endian byte order.
079         * @param value the Java int to convert to bytes
080         * @return the converted int as a byte array in big endian byte order
081         */
082        public static byte[] getBytes(int value) {
083            byte[] result = new byte[2];
084            result[0] = (byte) (value & BYTE_MASK);
085            result[1] = (byte) ((value & BYTE_1_MASK) >> BYTE_1_SHIFT);
086            return result;
087        }
088    
089        /**
090         * Helper method to get the value as a java int from two bytes starting at given array offset
091         * @param bytes the array of bytes
092         * @param offset the offset to start
093         * @return the corresponding java int value
094         */
095        public static int getValue(byte[] bytes, int offset) {
096            int value = (bytes[offset + 1] << BYTE_1_SHIFT) & BYTE_1_MASK;
097            value += (bytes[offset] & BYTE_MASK);
098            return value;
099        }
100    
101        /**
102         * Helper method to get the value as a java int from a two-byte array
103         * @param bytes the array of bytes
104         * @return the corresponding java int value
105         */
106        public static int getValue(byte[] bytes) {
107            return getValue(bytes, 0);
108        }
109    
110        /**
111         * Override to make two instances with same value equal.
112         * @param o an object to compare
113         * @return true if the objects are equal
114         */
115        @Override
116        public boolean equals(Object o) {
117            if (o == null || !(o instanceof ZipShort)) {
118                return false;
119            }
120            return value == ((ZipShort) o).getValue();
121        }
122    
123        /**
124         * Override to make two instances with same value equal.
125         * @return the value stored in the ZipShort
126         */
127        @Override
128        public int hashCode() {
129            return value;
130        }
131    
132        @Override
133        public Object clone() {
134            try {
135                return super.clone();
136            } catch (CloneNotSupportedException cnfe) {
137                // impossible
138                throw new RuntimeException(cnfe);
139            }
140        }
141    
142        @Override
143        public String toString() {
144            return "ZipShort value: " + value;
145        }
146    }