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.codec.binary;
019
020 import java.nio.charset.Charset;
021
022 import org.apache.commons.codec.BinaryDecoder;
023 import org.apache.commons.codec.BinaryEncoder;
024 import org.apache.commons.codec.CharEncoding;
025 import org.apache.commons.codec.Charsets;
026 import org.apache.commons.codec.DecoderException;
027 import org.apache.commons.codec.EncoderException;
028
029 /**
030 * Converts hexadecimal Strings. The charset used for certain operation can be set, the default is set in
031 * {@link #DEFAULT_CHARSET_NAME}
032 *
033 * This class is thread-safe.
034 *
035 * @since 1.1
036 * @version $Id: Hex.html 889935 2013-12-11 05:05:13Z ggregory $
037 */
038 public class Hex implements BinaryEncoder, BinaryDecoder {
039
040 /**
041 * Default charset name is {@link Charsets#UTF_8}
042 *
043 * @since 1.7
044 */
045 public static final Charset DEFAULT_CHARSET = Charsets.UTF_8;
046
047 /**
048 * Default charset name is {@link CharEncoding#UTF_8}
049 *
050 * @since 1.4
051 */
052 public static final String DEFAULT_CHARSET_NAME = CharEncoding.UTF_8;
053
054 /**
055 * Used to build output as Hex
056 */
057 private static final char[] DIGITS_LOWER =
058 {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
059
060 /**
061 * Used to build output as Hex
062 */
063 private static final char[] DIGITS_UPPER =
064 {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
065
066 /**
067 * Converts an array of characters representing hexadecimal values into an array of bytes of those same values. The
068 * returned array will be half the length of the passed array, as it takes two characters to represent any given
069 * byte. An exception is thrown if the passed char array has an odd number of elements.
070 *
071 * @param data
072 * An array of characters containing hexadecimal digits
073 * @return A byte array containing binary data decoded from the supplied char array.
074 * @throws DecoderException
075 * Thrown if an odd number or illegal of characters is supplied
076 */
077 public static byte[] decodeHex(final char[] data) throws DecoderException {
078
079 final int len = data.length;
080
081 if ((len & 0x01) != 0) {
082 throw new DecoderException("Odd number of characters.");
083 }
084
085 final byte[] out = new byte[len >> 1];
086
087 // two characters form the hex value.
088 for (int i = 0, j = 0; j < len; i++) {
089 int f = toDigit(data[j], j) << 4;
090 j++;
091 f = f | toDigit(data[j], j);
092 j++;
093 out[i] = (byte) (f & 0xFF);
094 }
095
096 return out;
097 }
098
099 /**
100 * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
101 * The returned array will be double the length of the passed array, as it takes two characters to represent any
102 * given byte.
103 *
104 * @param data
105 * a byte[] to convert to Hex characters
106 * @return A char[] containing hexadecimal characters
107 */
108 public static char[] encodeHex(final byte[] data) {
109 return encodeHex(data, true);
110 }
111
112 /**
113 * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
114 * The returned array will be double the length of the passed array, as it takes two characters to represent any
115 * given byte.
116 *
117 * @param data
118 * a byte[] to convert to Hex characters
119 * @param toLowerCase
120 * {@code true} converts to lowercase, {@code false} to uppercase
121 * @return A char[] containing hexadecimal characters
122 * @since 1.4
123 */
124 public static char[] encodeHex(final byte[] data, final boolean toLowerCase) {
125 return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
126 }
127
128 /**
129 * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
130 * The returned array will be double the length of the passed array, as it takes two characters to represent any
131 * given byte.
132 *
133 * @param data
134 * a byte[] to convert to Hex characters
135 * @param toDigits
136 * the output alphabet
137 * @return A char[] containing hexadecimal characters
138 * @since 1.4
139 */
140 protected static char[] encodeHex(final byte[] data, final char[] toDigits) {
141 final int l = data.length;
142 final char[] out = new char[l << 1];
143 // two characters form the hex value.
144 for (int i = 0, j = 0; i < l; i++) {
145 out[j++] = toDigits[(0xF0 & data[i]) >>> 4];
146 out[j++] = toDigits[0x0F & data[i]];
147 }
148 return out;
149 }
150
151 /**
152 * Converts an array of bytes into a String representing the hexadecimal values of each byte in order. The returned
153 * String will be double the length of the passed array, as it takes two characters to represent any given byte.
154 *
155 * @param data
156 * a byte[] to convert to Hex characters
157 * @return A String containing hexadecimal characters
158 * @since 1.4
159 */
160 public static String encodeHexString(final byte[] data) {
161 return new String(encodeHex(data));
162 }
163
164 /**
165 * Converts a hexadecimal character to an integer.
166 *
167 * @param ch
168 * A character to convert to an integer digit
169 * @param index
170 * The index of the character in the source
171 * @return An integer
172 * @throws DecoderException
173 * Thrown if ch is an illegal hex character
174 */
175 protected static int toDigit(final char ch, final int index) throws DecoderException {
176 final int digit = Character.digit(ch, 16);
177 if (digit == -1) {
178 throw new DecoderException("Illegal hexadecimal character " + ch + " at index " + index);
179 }
180 return digit;
181 }
182
183 private final Charset charset;
184
185 /**
186 * Creates a new codec with the default charset name {@link #DEFAULT_CHARSET}
187 */
188 public Hex() {
189 // use default encoding
190 this.charset = DEFAULT_CHARSET;
191 }
192
193 /**
194 * Creates a new codec with the given Charset.
195 *
196 * @param charset
197 * the charset.
198 * @since 1.7
199 */
200 public Hex(final Charset charset) {
201 this.charset = charset;
202 }
203
204 /**
205 * Creates a new codec with the given charset name.
206 *
207 * @param charsetName
208 * the charset name.
209 * @throws java.nio.charset.UnsupportedCharsetException
210 * If the named charset is unavailable
211 * @since 1.4
212 * @since 1.7 throws UnsupportedCharsetException if the named charset is unavailable
213 */
214 public Hex(final String charsetName) {
215 this(Charset.forName(charsetName));
216 }
217
218 /**
219 * Converts an array of character bytes representing hexadecimal values into an array of bytes of those same values.
220 * The returned array will be half the length of the passed array, as it takes two characters to represent any given
221 * byte. An exception is thrown if the passed char array has an odd number of elements.
222 *
223 * @param array
224 * An array of character bytes containing hexadecimal digits
225 * @return A byte array containing binary data decoded from the supplied byte array (representing characters).
226 * @throws DecoderException
227 * Thrown if an odd number of characters is supplied to this function
228 * @see #decodeHex(char[])
229 */
230 @Override
231 public byte[] decode(final byte[] array) throws DecoderException {
232 return decodeHex(new String(array, getCharset()).toCharArray());
233 }
234
235 /**
236 * Converts a String or an array of character bytes representing hexadecimal values into an array of bytes of those
237 * same values. The returned array will be half the length of the passed String or array, as it takes two characters
238 * to represent any given byte. An exception is thrown if the passed char array has an odd number of elements.
239 *
240 * @param object
241 * A String or, an array of character bytes containing hexadecimal digits
242 * @return A byte array containing binary data decoded from the supplied byte array (representing characters).
243 * @throws DecoderException
244 * Thrown if an odd number of characters is supplied to this function or the object is not a String or
245 * char[]
246 * @see #decodeHex(char[])
247 */
248 @Override
249 public Object decode(final Object object) throws DecoderException {
250 try {
251 final char[] charArray = object instanceof String ? ((String) object).toCharArray() : (char[]) object;
252 return decodeHex(charArray);
253 } catch (final ClassCastException e) {
254 throw new DecoderException(e.getMessage(), e);
255 }
256 }
257
258 /**
259 * Converts an array of bytes into an array of bytes for the characters representing the hexadecimal values of each
260 * byte in order. The returned array will be double the length of the passed array, as it takes two characters to
261 * represent any given byte.
262 * <p>
263 * The conversion from hexadecimal characters to the returned bytes is performed with the charset named by
264 * {@link #getCharset()}.
265 * </p>
266 *
267 * @param array
268 * a byte[] to convert to Hex characters
269 * @return A byte[] containing the bytes of the hexadecimal characters
270 * @since 1.7 No longer throws IllegalStateException if the charsetName is invalid.
271 * @see #encodeHex(byte[])
272 */
273 @Override
274 public byte[] encode(final byte[] array) {
275 return encodeHexString(array).getBytes(this.getCharset());
276 }
277
278 /**
279 * Converts a String or an array of bytes into an array of characters representing the hexadecimal values of each
280 * byte in order. The returned array will be double the length of the passed String or array, as it takes two
281 * characters to represent any given byte.
282 * <p>
283 * The conversion from hexadecimal characters to bytes to be encoded to performed with the charset named by
284 * {@link #getCharset()}.
285 * </p>
286 *
287 * @param object
288 * a String, or byte[] to convert to Hex characters
289 * @return A char[] containing hexadecimal characters
290 * @throws EncoderException
291 * Thrown if the given object is not a String or byte[]
292 * @see #encodeHex(byte[])
293 */
294 @Override
295 public Object encode(final Object object) throws EncoderException {
296 try {
297 final byte[] byteArray = object instanceof String ?
298 ((String) object).getBytes(this.getCharset()) : (byte[]) object;
299 return encodeHex(byteArray);
300 } catch (final ClassCastException e) {
301 throw new EncoderException(e.getMessage(), e);
302 }
303 }
304
305 /**
306 * Gets the charset.
307 *
308 * @return the charset.
309 * @since 1.7
310 */
311 public Charset getCharset() {
312 return this.charset;
313 }
314
315 /**
316 * Gets the charset name.
317 *
318 * @return the charset name.
319 * @since 1.4
320 */
321 public String getCharsetName() {
322 return this.charset.name();
323 }
324
325 /**
326 * Returns a string representation of the object, which includes the charset name.
327 *
328 * @return a string representation of the object.
329 */
330 @Override
331 public String toString() {
332 return super.toString() + "[charsetName=" + this.charset + "]";
333 }
334 }