1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.io;
18
19 import java.io.Serializable;
20
21 /**
22 * Byte Order Mark (BOM) representation - see {@link org.apache.commons.io.input.BOMInputStream}.
23 *
24 * @see org.apache.commons.io.input.BOMInputStream
25 * @see <a href="http://en.wikipedia.org/wiki/Byte_order_mark">Wikipedia: Byte Order Mark</a>
26 * @see <a href="http://www.w3.org/TR/2006/REC-xml-20060816/#sec-guessing">W3C: Autodetection of Character Encodings
27 * (Non-Normative)</a>
28 * @version $Id: ByteOrderMark.java 1471767 2013-04-24 23:24:19Z sebb $
29 * @since 2.0
30 */
31 public class ByteOrderMark implements Serializable {
32
33 private static final long serialVersionUID = 1L;
34
35 /** UTF-8 BOM */
36 public static final ByteOrderMark UTF_8 = new ByteOrderMark("UTF-8", 0xEF, 0xBB, 0xBF);
37
38 /** UTF-16BE BOM (Big-Endian) */
39 public static final ByteOrderMark UTF_16BE = new ByteOrderMark("UTF-16BE", 0xFE, 0xFF);
40
41 /** UTF-16LE BOM (Little-Endian) */
42 public static final ByteOrderMark UTF_16LE = new ByteOrderMark("UTF-16LE", 0xFF, 0xFE);
43
44 /**
45 * UTF-32BE BOM (Big-Endian)
46 * @since 2.2
47 */
48 public static final ByteOrderMark UTF_32BE = new ByteOrderMark("UTF-32BE", 0x00, 0x00, 0xFE, 0xFF);
49
50 /**
51 * UTF-32LE BOM (Little-Endian)
52 * @since 2.2
53 */
54 public static final ByteOrderMark UTF_32LE = new ByteOrderMark("UTF-32LE", 0xFF, 0xFE, 0x00, 0x00);
55
56 /**
57 * Unicode BOM character; external form depends on the encoding.
58 * @see <a href="http://unicode.org/faq/utf_bom.html#BOM">Byte Order Mark (BOM) FAQ</a>
59 * @since 2.5
60 */
61 public static final char UTF_BOM = '\uFEFF';
62
63 private final String charsetName;
64 private final int[] bytes;
65
66 /**
67 * Construct a new BOM.
68 *
69 * @param charsetName The name of the charset the BOM represents
70 * @param bytes The BOM's bytes
71 * @throws IllegalArgumentException if the charsetName is null or
72 * zero length
73 * @throws IllegalArgumentException if the bytes are null or zero
74 * length
75 */
76 public ByteOrderMark(final String charsetName, final int... bytes) {
77 if (charsetName == null || charsetName.length() == 0) {
78 throw new IllegalArgumentException("No charsetName specified");
79 }
80 if (bytes == null || bytes.length == 0) {
81 throw new IllegalArgumentException("No bytes specified");
82 }
83 this.charsetName = charsetName;
84 this.bytes = new int[bytes.length];
85 System.arraycopy(bytes, 0, this.bytes, 0, bytes.length);
86 }
87
88 /**
89 * Return the name of the {@link java.nio.charset.Charset} the BOM represents.
90 *
91 * @return the character set name
92 */
93 public String getCharsetName() {
94 return charsetName;
95 }
96
97 /**
98 * Return the length of the BOM's bytes.
99 *
100 * @return the length of the BOM's bytes
101 */
102 public int length() {
103 return bytes.length;
104 }
105
106 /**
107 * The byte at the specified position.
108 *
109 * @param pos The position
110 * @return The specified byte
111 */
112 public int get(final int pos) {
113 return bytes[pos];
114 }
115
116 /**
117 * Return a copy of the BOM's bytes.
118 *
119 * @return a copy of the BOM's bytes
120 */
121 public byte[] getBytes() {
122 final byte[] copy = new byte[bytes.length];
123 for (int i = 0; i < bytes.length; i++) {
124 copy[i] = (byte)bytes[i];
125 }
126 return copy;
127 }
128
129 /**
130 * Indicates if this BOM's bytes equals another.
131 *
132 * @param obj The object to compare to
133 * @return true if the bom's bytes are equal, otherwise
134 * false
135 */
136 @Override
137 public boolean equals(final Object obj) {
138 if (!(obj instanceof ByteOrderMark)) {
139 return false;
140 }
141 final ByteOrderMark bom = (ByteOrderMark)obj;
142 if (bytes.length != bom.length()) {
143 return false;
144 }
145 for (int i = 0; i < bytes.length; i++) {
146 if (bytes[i] != bom.get(i)) {
147 return false;
148 }
149 }
150 return true;
151 }
152
153 /**
154 * Return the hashcode for this BOM.
155 *
156 * @return the hashcode for this BOM.
157 * @see java.lang.Object#hashCode()
158 */
159 @Override
160 public int hashCode() {
161 int hashCode = getClass().hashCode();
162 for (final int b : bytes) {
163 hashCode += b;
164 }
165 return hashCode;
166 }
167
168 /**
169 * Provide a String representation of the BOM.
170 *
171 * @return the length of the BOM's bytes
172 */
173 @Override
174 public String toString() {
175 final StringBuilder builder = new StringBuilder();
176 builder.append(getClass().getSimpleName());
177 builder.append('[');
178 builder.append(charsetName);
179 builder.append(": ");
180 for (int i = 0; i < bytes.length; i++) {
181 if (i > 0) {
182 builder.append(",");
183 }
184 builder.append("0x");
185 builder.append(Integer.toHexString(0xFF & bytes[i]).toUpperCase());
186 }
187 builder.append(']');
188 return builder.toString();
189 }
190
191 }