001 /**
002 * GRANITE DATA SERVICES
003 * Copyright (C) 2006-2013 GRANITE DATA SERVICES S.A.S.
004 *
005 * This file is part of the Granite Data Services Platform.
006 *
007 * Granite Data Services is free software; you can redistribute it and/or
008 * modify it under the terms of the GNU Lesser General Public
009 * License as published by the Free Software Foundation; either
010 * version 2.1 of the License, or (at your option) any later version.
011 *
012 * Granite Data Services is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
015 * General Public License for more details.
016 *
017 * You should have received a copy of the GNU Lesser General Public
018 * License along with this library; if not, write to the Free Software
019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
020 * USA, or see <http://www.gnu.org/licenses/>.
021 */
022 package org.granite.util;
023
024 import java.util.Arrays;
025
026 /** A very fast and memory efficient class to encode and decode to and from BASE64 in full accordance
027 * with RFC 2045.<br><br>
028 * On Windows XP sp1 with 1.4.2_04 and later ;), this encoder and decoder is about 10 times faster
029 * on small arrays (10 - 1000 bytes) and 2-3 times as fast on larger arrays (10000 - 1000000 bytes)
030 * compared to <code>sun.misc.Encoder()/Decoder()</code>.<br><br>
031 *
032 * On byte arrays the encoder is about 20% faster than Jakarta Commons Base64 Codec for encode and
033 * about 50% faster for decoding large arrays. This implementation is about twice as fast on very small
034 * arrays (< 30 bytes). If source/destination is a <code>String</code> this
035 * version is about three times as fast due to the fact that the Commons Codec result has to be recoded
036 * to a <code>String</code> from <code>byte[]</code>, which is very expensive.<br><br>
037 *
038 * This encode/decode algorithm doesn't create any temporary arrays as many other codecs do, it only
039 * allocates the resulting array. This produces less garbage and it is possible to handle arrays twice
040 * as large as algorithms that create a temporary array. (E.g. Jakarta Commons Codec). It is unknown
041 * whether Sun's <code>sun.misc.Encoder()/Decoder()</code> produce temporary arrays but since performance
042 * is quite low it probably does.<br><br>
043 *
044 * The encoder produces the same output as the Sun one except that the Sun's encoder appends
045 * a trailing line separator if the last character isn't a pad. Unclear why but it only adds to the
046 * length and is probably a side effect. Both are in conformance with RFC 2045 though.<br>
047 * Commons codec seem to always att a trailing line separator.<br><br>
048 *
049 * <b>Note!</b>
050 * The encode/decode method pairs (types) come in three versions with the <b>exact</b> same algorithm and
051 * thus a lot of code redundancy. This is to not create any temporary arrays for transcoding to/from different
052 * format types. The methods not used can simply be commented out.<br><br>
053 *
054 * There is also a "fast" version of all decode methods that works the same way as the normal ones, but
055 * har a few demands on the decoded input. Normally though, these fast verions should be used if the source if
056 * the input is known and it hasn't bee tampered with.<br><br>
057 *
058 * If you find the code useful or you find a bug, please send me a note at base64 @ miginfocom . com.
059 *
060 * Licence (BSD):
061 * ==============
062 *
063 * Copyright (c) 2004, Mikael Grev, MiG InfoCom AB. (base64 @ miginfocom . com)
064 * All rights reserved.
065 *
066 * Redistribution and use in source and binary forms, with or without modification,
067 * are permitted provided that the following conditions are met:
068 * Redistributions of source code must retain the above copyright notice, this list
069 * of conditions and the following disclaimer.
070 * Redistributions in binary form must reproduce the above copyright notice, this
071 * list of conditions and the following disclaimer in the documentation and/or other
072 * materials provided with the distribution.
073 * Neither the name of the MiG InfoCom AB nor the names of its contributors may be
074 * used to endorse or promote products derived from this software without specific
075 * prior written permission.
076 *
077 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
078 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
079 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
080 * IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
081 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
082 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
083 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
084 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
085 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
086 * OF SUCH DAMAGE.
087 *
088 * @version 2.2
089 * @author Mikael Grev
090 * Date: 2004-aug-02
091 * Time: 11:31:11
092 */
093
094 public class Base64
095 {
096 private static final char[] CA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
097 private static final int[] IA = new int[256];
098 static {
099 Arrays.fill(IA, -1);
100 for (int i = 0, iS = CA.length; i < iS; i++)
101 IA[CA[i]] = i;
102 IA['='] = 0;
103 }
104
105 // ****************************************************************************************
106 // * char[] version
107 // ****************************************************************************************
108
109 /** Encodes a raw byte array into a BASE64 <code>char[]</code> representation i accordance with RFC 2045.
110 * @param sArr The bytes to convert. If <code>null</code> or length 0 an empty array will be returned.
111 * @param lineSep Optional "\r\n" after 76 characters, unless end of file.<br>
112 * No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a
113 * little faster.
114 * @return A BASE64 encoded array. Never <code>null</code>.
115 */
116 public final static char[] encodeToChar(byte[] sArr, boolean lineSep)
117 {
118 // Check special case
119 if (sArr == null || sArr.length == 0)
120 return new char[0];
121
122 int sLen = sArr.length;
123 int eLen = (sLen / 3) * 3; // Length of even 24-bits.
124 int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count
125 int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of returned array
126 char[] dArr = new char[dLen];
127
128 // Encode even 24-bits
129 for (int s = 0, d = 0, cc = 0; s < eLen;) {
130 // Copy next three bytes into lower 24 bits of int, paying attension to sign.
131 int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);
132
133 // Encode the int into four chars
134 dArr[d++] = CA[(i >>> 18) & 0x3f];
135 dArr[d++] = CA[(i >>> 12) & 0x3f];
136 dArr[d++] = CA[(i >>> 6) & 0x3f];
137 dArr[d++] = CA[i & 0x3f];
138
139 // Add optional line separator
140 if (lineSep && ++cc == 19 && d < dLen - 2) {
141 dArr[d++] = '\r';
142 dArr[d++] = '\n';
143 cc = 0;
144 }
145 }
146
147 // Pad and encode last bits if source isn't even 24 bits.
148 int left = sLen - eLen; // 0 - 2.
149 if (left > 0) {
150 // Prepare the int
151 int i = ((sArr[eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);
152
153 // Set last four chars
154 dArr[dLen - 4] = CA[i >> 12];
155 dArr[dLen - 3] = CA[(i >>> 6) & 0x3f];
156 dArr[dLen - 2] = left == 2 ? CA[i & 0x3f] : '=';
157 dArr[dLen - 1] = '=';
158 }
159 return dArr;
160 }
161
162 /** Decodes a BASE64 encoded char array. All illegal characters will be ignored and can handle both arrays with
163 * and without line separators.
164 * @param sArr The source array. <code>null</code> or length 0 will return an empty array.
165 * @return The decoded array of bytes. May be of length 0. Will be <code>null</code> if the legal characters
166 * (including '=') isn't divideable by 4. (I.e. definitely corrupted).
167 */
168 public final static byte[] decode(char[] sArr)
169 {
170 // Check special case
171 if (sArr == null || sArr.length == 0)
172 return new byte[0];
173
174 int sLen = sArr.length;
175
176 // Count illegal characters (including '\r', '\n') to know what size the returned array will be,
177 // so we don't have to reallocate & copy it later.
178 int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...)
179 for (int i = 0; i < sLen; i++) // If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out.
180 if (IA[sArr[i]] < 0)
181 sepCnt++;
182
183 // Check so that legal chars (including '=') are evenly divideable by 4 as specified in RFC 2045.
184 if ((sLen - sepCnt) % 4 != 0)
185 return null;
186
187 int pad = 0;
188 for (int i = sLen; i > 1 && IA[sArr[--i]] <= 0;)
189 if (sArr[i] == '=')
190 pad++;
191
192 int len = ((sLen - sepCnt) * 6 >> 3) - pad;
193
194 byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
195
196 for (int s = 0, d = 0; d < len;) {
197 // Assemble three bytes into an int from four "valid" characters.
198 int i = 0;
199 for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
200 int c = IA[sArr[s++]];
201 if (c >= 0)
202 i |= c << (18 - j * 6);
203 else
204 j--;
205 }
206 // Add the bytes
207 dArr[d++] = (byte) (i >> 16);
208 if (d < len) {
209 dArr[d++]= (byte) (i >> 8);
210 if (d < len)
211 dArr[d++] = (byte) i;
212 }
213 }
214 return dArr;
215 }
216
217 /** Decodes a BASE64 encoded char array that is known to be resonably well formatted. The method is about twice as
218 * fast as {@link #decode(char[])}. The preconditions are:<br>
219 * + The array must have a line length of 76 chars OR no line separators at all (one line).<br>
220 * + Line separator must be "\r\n", as specified in RFC 2045
221 * + The array must not contain illegal characters within the encoded string<br>
222 * + The array CAN have illegal characters at the beginning and end, those will be dealt with appropriately.<br>
223 * @param sArr The source array. Length 0 will return an empty array. <code>null</code> will throw an exception.
224 * @return The decoded array of bytes. May be of length 0.
225 */
226 public final static byte[] decodeFast(char[] sArr)
227 {
228 // Check special case
229 int sLen = sArr.length;
230 if (sLen == 0)
231 return new byte[0];
232
233 int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.
234
235 // Trim illegal chars from start
236 while (sIx < eIx && IA[sArr[sIx]] < 0)
237 sIx++;
238
239 // Trim illegal chars from end
240 while (eIx > 0 && IA[sArr[eIx]] < 0)
241 eIx--;
242
243 // get the padding count (=) (0, 1 or 2)
244 int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count '=' at end.
245 int cCnt = eIx - sIx + 1; // Content count including possible separators
246 int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;
247
248 int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes
249 byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
250
251 // Decode all but the last 0 - 2 bytes.
252 int d = 0;
253 for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
254 // Assemble three bytes into an int from four "valid" characters.
255 int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];
256
257 // Add the bytes
258 dArr[d++] = (byte) (i >> 16);
259 dArr[d++] = (byte) (i >> 8);
260 dArr[d++] = (byte) i;
261
262 // If line separator, jump over it.
263 if (sepCnt > 0 && ++cc == 19) {
264 sIx += 2;
265 cc = 0;
266 }
267 }
268
269 if (d < len) {
270 // Decode last 1-3 bytes (incl '=') into 1-3 bytes
271 int i = 0;
272 for (int j = 0; sIx <= eIx - pad; j++)
273 i |= IA[sArr[sIx++]] << (18 - j * 6);
274
275 for (int r = 16; d < len; r -= 8)
276 dArr[d++] = (byte) (i >> r);
277 }
278
279 return dArr;
280 }
281
282 // ****************************************************************************************
283 // * byte[] version
284 // ****************************************************************************************
285
286 /** Encodes a raw byte array into a BASE64 <code>byte[]</code> representation i accordance with RFC 2045.
287 * @param sArr The bytes to convert. If <code>null</code> or length 0 an empty array will be returned.
288 * @param lineSep Optional "\r\n" after 76 characters, unless end of file.<br>
289 * No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a
290 * little faster.
291 * @return A BASE64 encoded array. Never <code>null</code>.
292 */
293 public final static byte[] encodeToByte(byte[] sArr, boolean lineSep)
294 {
295 // Check special case
296 if (sArr == null || sArr.length == 0)
297 return new byte[0];
298
299 int sLen = sArr.length;
300 int eLen = (sLen / 3) * 3; // Length of even 24-bits.
301 int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count
302 int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of returned array
303 byte[] dArr = new byte[dLen];
304
305 // Encode even 24-bits
306 for (int s = 0, d = 0, cc = 0; s < eLen;) {
307 // Copy next three bytes into lower 24 bits of int, paying attension to sign.
308 int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);
309
310 // Encode the int into four chars
311 dArr[d++] = (byte) CA[(i >>> 18) & 0x3f];
312 dArr[d++] = (byte) CA[(i >>> 12) & 0x3f];
313 dArr[d++] = (byte) CA[(i >>> 6) & 0x3f];
314 dArr[d++] = (byte) CA[i & 0x3f];
315
316 // Add optional line separator
317 if (lineSep && ++cc == 19 && d < dLen - 2) {
318 dArr[d++] = '\r';
319 dArr[d++] = '\n';
320 cc = 0;
321 }
322 }
323
324 // Pad and encode last bits if source isn't an even 24 bits.
325 int left = sLen - eLen; // 0 - 2.
326 if (left > 0) {
327 // Prepare the int
328 int i = ((sArr[eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);
329
330 // Set last four chars
331 dArr[dLen - 4] = (byte) CA[i >> 12];
332 dArr[dLen - 3] = (byte) CA[(i >>> 6) & 0x3f];
333 dArr[dLen - 2] = left == 2 ? (byte) CA[i & 0x3f] : (byte) '=';
334 dArr[dLen - 1] = '=';
335 }
336 return dArr;
337 }
338
339 /** Decodes a BASE64 encoded byte array. All illegal characters will be ignored and can handle both arrays with
340 * and without line separators.
341 * @param sArr The source array. Length 0 will return an empty array. <code>null</code> will throw an exception.
342 * @return The decoded array of bytes. May be of length 0. Will be <code>null</code> if the legal characters
343 * (including '=') isn't divideable by 4. (I.e. definitely corrupted).
344 */
345 public final static byte[] decode(byte[] sArr)
346 {
347 // Check special case
348 int sLen = sArr.length;
349
350 // Count illegal characters (including '\r', '\n') to know what size the returned array will be,
351 // so we don't have to reallocate & copy it later.
352 int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...)
353 for (int i = 0; i < sLen; i++) // If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out.
354 if (IA[sArr[i] & 0xff] < 0)
355 sepCnt++;
356
357 // Check so that legal chars (including '=') are evenly divideable by 4 as specified in RFC 2045.
358 if ((sLen - sepCnt) % 4 != 0)
359 return null;
360
361 int pad = 0;
362 for (int i = sLen; i > 1 && IA[sArr[--i] & 0xff] <= 0;)
363 if (sArr[i] == '=')
364 pad++;
365
366 int len = ((sLen - sepCnt) * 6 >> 3) - pad;
367
368 byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
369
370 for (int s = 0, d = 0; d < len;) {
371 // Assemble three bytes into an int from four "valid" characters.
372 int i = 0;
373 for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
374 int c = IA[sArr[s++] & 0xff];
375 if (c >= 0)
376 i |= c << (18 - j * 6);
377 else
378 j--;
379 }
380
381 // Add the bytes
382 dArr[d++] = (byte) (i >> 16);
383 if (d < len) {
384 dArr[d++]= (byte) (i >> 8);
385 if (d < len)
386 dArr[d++] = (byte) i;
387 }
388 }
389
390 return dArr;
391 }
392
393
394 /** Decodes a BASE64 encoded byte array that is known to be resonably well formatted. The method is about twice as
395 * fast as {@link #decode(byte[])}. The preconditions are:<br>
396 * + The array must have a line length of 76 chars OR no line separators at all (one line).<br>
397 * + Line separator must be "\r\n", as specified in RFC 2045
398 * + The array must not contain illegal characters within the encoded string<br>
399 * + The array CAN have illegal characters at the beginning and end, those will be dealt with appropriately.<br>
400 * @param sArr The source array. Length 0 will return an empty array. <code>null</code> will throw an exception.
401 * @return The decoded array of bytes. May be of length 0.
402 */
403 public final static byte[] decodeFast(byte[] sArr)
404 {
405 // Check special case
406 int sLen = sArr.length;
407 if (sLen == 0)
408 return new byte[0];
409
410 int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.
411
412 // Trim illegal chars from start
413 while (sIx < eIx && IA[sArr[sIx] & 0xff] < 0)
414 sIx++;
415
416 // Trim illegal chars from end
417 while (eIx > 0 && IA[sArr[eIx] & 0xff] < 0)
418 eIx--;
419
420 // get the padding count (=) (0, 1 or 2)
421 int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count '=' at end.
422 int cCnt = eIx - sIx + 1; // Content count including possible separators
423 int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;
424
425 int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes
426 byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
427
428 // Decode all but the last 0 - 2 bytes.
429 int d = 0;
430 for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
431 // Assemble three bytes into an int from four "valid" characters.
432 int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];
433
434 // Add the bytes
435 dArr[d++] = (byte) (i >> 16);
436 dArr[d++] = (byte) (i >> 8);
437 dArr[d++] = (byte) i;
438
439 // If line separator, jump over it.
440 if (sepCnt > 0 && ++cc == 19) {
441 sIx += 2;
442 cc = 0;
443 }
444 }
445
446 if (d < len) {
447 // Decode last 1-3 bytes (incl '=') into 1-3 bytes
448 int i = 0;
449 for (int j = 0; sIx <= eIx - pad; j++)
450 i |= IA[sArr[sIx++]] << (18 - j * 6);
451
452 for (int r = 16; d < len; r -= 8)
453 dArr[d++] = (byte) (i >> r);
454 }
455
456 return dArr;
457 }
458
459 // ****************************************************************************************
460 // * String version
461 // ****************************************************************************************
462
463 /** Encodes a raw byte array into a BASE64 <code>String</code> representation i accordance with RFC 2045.
464 * @param sArr The bytes to convert. If <code>null</code> or length 0 an empty array will be returned.
465 * @param lineSep Optional "\r\n" after 76 characters, unless end of file.<br>
466 * No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a
467 * little faster.
468 * @return A BASE64 encoded array. Never <code>null</code>.
469 */
470 public final static String encodeToString(byte[] sArr, boolean lineSep)
471 {
472 // Reuse char[] since we can't create a String incrementally anyway and StringBuffer/Builder would be slower.
473 return new String(encodeToChar(sArr, lineSep));
474 }
475
476 /** Decodes a BASE64 encoded <code>String</code>. All illegal characters will be ignored and can handle both strings with
477 * and without line separators.<br>
478 * <b>Note!</b> It can be up to about 2x the speed to call <code>decode(str.toCharArray())</code> instead. That
479 * will create a temporary array though. This version will use <code>str.charAt(i)</code> to iterate the string.
480 * @param str The source string. <code>null</code> or length 0 will return an empty array.
481 * @return The decoded array of bytes. May be of length 0. Will be <code>null</code> if the legal characters
482 * (including '=') isn't divideable by 4. (I.e. definitely corrupted).
483 */
484 public final static byte[] decode(String str)
485 {
486 // Check special case
487 if (str == null || str.length() == 0)
488 return new byte[0];
489
490 int sLen = str.length();
491
492 // Count illegal characters (including '\r', '\n') to know what size the returned array will be,
493 // so we don't have to reallocate & copy it later.
494 int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...)
495 for (int i = 0; i < sLen; i++) // If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out.
496 if (IA[str.charAt(i)] < 0)
497 sepCnt++;
498
499 // Check so that legal chars (including '=') are evenly divideable by 4 as specified in RFC 2045.
500 if ((sLen - sepCnt) % 4 != 0)
501 return null;
502
503 // Count '=' at end
504 int pad = 0;
505 for (int i = sLen; i > 1 && IA[str.charAt(--i)] <= 0;)
506 if (str.charAt(i) == '=')
507 pad++;
508
509 int len = ((sLen - sepCnt) * 6 >> 3) - pad;
510
511 byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
512
513 for (int s = 0, d = 0; d < len;) {
514 // Assemble three bytes into an int from four "valid" characters.
515 int i = 0;
516 for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
517 int c = IA[str.charAt(s++)];
518 if (c >= 0)
519 i |= c << (18 - j * 6);
520 else
521 j--;
522 }
523 // Add the bytes
524 dArr[d++] = (byte) (i >> 16);
525 if (d < len) {
526 dArr[d++]= (byte) (i >> 8);
527 if (d < len)
528 dArr[d++] = (byte) i;
529 }
530 }
531 return dArr;
532 }
533
534 /** Decodes a BASE64 encoded string that is known to be resonably well formatted. The method is about twice as
535 * fast as {@link #decode(String)}. The preconditions are:<br>
536 * + The array must have a line length of 76 chars OR no line separators at all (one line).<br>
537 * + Line separator must be "\r\n", as specified in RFC 2045
538 * + The array must not contain illegal characters within the encoded string<br>
539 * + The array CAN have illegal characters at the beginning and end, those will be dealt with appropriately.<br>
540 * @param s The source string. Length 0 will return an empty array. <code>null</code> will throw an exception.
541 * @return The decoded array of bytes. May be of length 0.
542 */
543 public final static byte[] decodeFast(String s)
544 {
545 // Check special case
546 if (s == null || s.length() == 0)
547 return new byte[0];
548
549 int sLen = s.length();
550 int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.
551
552 // Trim illegal chars from start
553 while (sIx < eIx && IA[s.charAt(sIx) & 0xff] < 0)
554 sIx++;
555
556 // Trim illegal chars from end
557 while (eIx > 0 && IA[s.charAt(eIx) & 0xff] < 0)
558 eIx--;
559
560 // get the padding count (=) (0, 1 or 2)
561 int pad = s.charAt(eIx) == '=' ? (s.charAt(eIx - 1) == '=' ? 2 : 1) : 0; // Count '=' at end.
562 int cCnt = eIx - sIx + 1; // Content count including possible separators
563 int sepCnt = sLen > 76 ? (s.charAt(76) == '\r' ? cCnt / 78 : 0) << 1 : 0;
564
565 int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes
566 byte[] dArr = new byte[len]; // Preallocate byte[] of exact length
567
568 // Decode all but the last 0 - 2 bytes.
569 int d = 0;
570 for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
571 // Assemble three bytes into an int from four "valid" characters.
572 int i = IA[s.charAt(sIx++)] << 18 | IA[s.charAt(sIx++)] << 12 | IA[s.charAt(sIx++)] << 6 | IA[s.charAt(sIx++)];
573
574 // Add the bytes
575 dArr[d++] = (byte) (i >> 16);
576 dArr[d++] = (byte) (i >> 8);
577 dArr[d++] = (byte) i;
578
579 // If line separator, jump over it.
580 if (sepCnt > 0 && ++cc == 19) {
581 sIx += 2;
582 cc = 0;
583 }
584 }
585
586 if (d < len) {
587 // Decode last 1-3 bytes (incl '=') into 1-3 bytes
588 int i = 0;
589 for (int j = 0; sIx <= eIx - pad; j++)
590 i |= IA[s.charAt(sIx++)] << (18 - j * 6);
591
592 for (int r = 16; d < len; r -= 8)
593 dArr[d++] = (byte) (i >> r);
594 }
595
596 return dArr;
597 }
598 }