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 java.io.Serializable;
021    
022    import static org.apache.commons.compress.archivers.zip.ZipConstants.BYTE_MASK;
023    
024    /**
025     * Utility class that represents a two byte integer with conversion
026     * rules for the big endian byte order of ZIP files.
027     * @Immutable
028     */
029    public final class ZipShort implements Cloneable, Serializable {
030        private static final long serialVersionUID = 1L;
031    
032        private static final int BYTE_1_MASK = 0xFF00;
033        private static final int BYTE_1_SHIFT = 8;
034    
035        private final int value;
036    
037        /**
038         * Create instance from a number.
039         * @param value the int to store as a ZipShort
040         */
041        public ZipShort (int value) {
042            this.value = value;
043        }
044    
045        /**
046         * Create instance from bytes.
047         * @param bytes the bytes to store as a ZipShort
048         */
049        public ZipShort (byte[] bytes) {
050            this(bytes, 0);
051        }
052    
053        /**
054         * Create instance from the two bytes starting at offset.
055         * @param bytes the bytes to store as a ZipShort
056         * @param offset the offset to start
057         */
058        public ZipShort (byte[] bytes, int offset) {
059            value = ZipShort.getValue(bytes, offset);
060        }
061    
062        /**
063         * Get value as two bytes in big endian byte order.
064         * @return the value as a a two byte array in big endian byte order
065         */
066        public byte[] getBytes() {
067            byte[] result = new byte[2];
068            result[0] = (byte) (value & BYTE_MASK);
069            result[1] = (byte) ((value & BYTE_1_MASK) >> BYTE_1_SHIFT);
070            return result;
071        }
072    
073        /**
074         * Get value as Java int.
075         * @return value as a Java int
076         */
077        public int getValue() {
078            return value;
079        }
080    
081        /**
082         * Get value as two bytes in big endian byte order.
083         * @param value the Java int to convert to bytes
084         * @return the converted int as a byte array in big endian byte order
085         */
086        public static byte[] getBytes(int value) {
087            byte[] result = new byte[2];
088            result[0] = (byte) (value & BYTE_MASK);
089            result[1] = (byte) ((value & BYTE_1_MASK) >> BYTE_1_SHIFT);
090            return result;
091        }
092    
093        /**
094         * Helper method to get the value as a java int from two bytes starting at given array offset
095         * @param bytes the array of bytes
096         * @param offset the offset to start
097         * @return the corresponding java int value
098         */
099        public static int getValue(byte[] bytes, int offset) {
100            int value = (bytes[offset + 1] << BYTE_1_SHIFT) & BYTE_1_MASK;
101            value += (bytes[offset] & BYTE_MASK);
102            return value;
103        }
104    
105        /**
106         * Helper method to get the value as a java int from a two-byte array
107         * @param bytes the array of bytes
108         * @return the corresponding java int value
109         */
110        public static int getValue(byte[] bytes) {
111            return getValue(bytes, 0);
112        }
113    
114        /**
115         * Override to make two instances with same value equal.
116         * @param o an object to compare
117         * @return true if the objects are equal
118         */
119        @Override
120        public boolean equals(Object o) {
121            if (o == null || !(o instanceof ZipShort)) {
122                return false;
123            }
124            return value == ((ZipShort) o).getValue();
125        }
126    
127        /**
128         * Override to make two instances with same value equal.
129         * @return the value stored in the ZipShort
130         */
131        @Override
132        public int hashCode() {
133            return value;
134        }
135    
136        @Override
137        public Object clone() {
138            try {
139                return super.clone();
140            } catch (CloneNotSupportedException cnfe) {
141                // impossible
142                throw new RuntimeException(cnfe);
143            }
144        }
145    
146        @Override
147        public String toString() {
148            return "ZipShort value: " + value;
149        }
150    }