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4 * distributed with this work for additional information        *
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13 * software distributed under the License is distributed on an  *
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19
20package org.apache.james.mime4j.util;
21
22import java.io.UnsupportedEncodingException;
23import java.nio.charset.IllegalCharsetNameException;
24import java.nio.charset.UnsupportedCharsetException;
25import java.util.HashMap;
26import java.util.TreeSet;
27
28//BEGIN android-changed: Stubbing out logging
29import org.apache.james.mime4j.Log;
30import org.apache.james.mime4j.LogFactory;
31//END android-changed
32
33/**
34 * Utility class for working with character sets. It is somewhat similar to
35 * the Java 1.4 <code>java.nio.charset.Charset</code> class but knows many
36 * more aliases and is compatible with Java 1.3. It will use a simple detection
37 * mechanism to detect what character sets the current VM supports. This will
38 * be a sub-set of the character sets listed in the
39 * <a href="http://java.sun.com/j2se/1.5.0/docs/guide/intl/encoding.doc.html">
40 * Java 1.5 (J2SE5.0) Supported Encodings</a> document.
41 * <p>
42 * The <a href="http://www.iana.org/assignments/character-sets">
43 * IANA Character Sets</a> document has been used to determine the preferred
44 * MIME character set names and to get a list of known aliases.
45 * <p>
46 * This is a complete list of the character sets known to this class:
47 * <table>
48 *     <tr>
49 *         <td>Canonical (Java) name</td>
50 *         <td>MIME preferred</td>
51 *         <td>Aliases</td>
52 *     </tr>
53 *     <tr>
54 *         <td>ASCII</td>
55 *         <td>US-ASCII</td>
56 *         <td>ANSI_X3.4-1968 iso-ir-6 ANSI_X3.4-1986 ISO_646.irv:1991 ISO646-US us IBM367 cp367 csASCII ascii7 646 iso_646.irv:1983 </td>
57 *     </tr>
58 *     <tr>
59 *         <td>Big5</td>
60 *         <td>Big5</td>
61 *         <td>csBig5 CN-Big5 BIG-FIVE BIGFIVE </td>
62 *     </tr>
63 *     <tr>
64 *         <td>Big5_HKSCS</td>
65 *         <td>Big5-HKSCS</td>
66 *         <td>big5hkscs </td>
67 *     </tr>
68 *     <tr>
69 *         <td>Big5_Solaris</td>
70 *         <td>?</td>
71 *         <td></td>
72 *     </tr>
73 *     <tr>
74 *         <td>Cp037</td>
75 *         <td>IBM037</td>
76 *         <td>ebcdic-cp-us ebcdic-cp-ca ebcdic-cp-wt ebcdic-cp-nl csIBM037 </td>
77 *     </tr>
78 *     <tr>
79 *         <td>Cp1006</td>
80 *         <td>?</td>
81 *         <td></td>
82 *     </tr>
83 *     <tr>
84 *         <td>Cp1025</td>
85 *         <td>?</td>
86 *         <td></td>
87 *     </tr>
88 *     <tr>
89 *         <td>Cp1026</td>
90 *         <td>IBM1026</td>
91 *         <td>csIBM1026 </td>
92 *     </tr>
93 *     <tr>
94 *         <td>Cp1046</td>
95 *         <td>?</td>
96 *         <td></td>
97 *     </tr>
98 *     <tr>
99 *         <td>Cp1047</td>
100 *         <td>IBM1047</td>
101 *         <td>IBM-1047 </td>
102 *     </tr>
103 *     <tr>
104 *         <td>Cp1097</td>
105 *         <td>?</td>
106 *         <td></td>
107 *     </tr>
108 *     <tr>
109 *         <td>Cp1098</td>
110 *         <td>?</td>
111 *         <td></td>
112 *     </tr>
113 *     <tr>
114 *         <td>Cp1112</td>
115 *         <td>?</td>
116 *         <td></td>
117 *     </tr>
118 *     <tr>
119 *         <td>Cp1122</td>
120 *         <td>?</td>
121 *         <td></td>
122 *     </tr>
123 *     <tr>
124 *         <td>Cp1123</td>
125 *         <td>?</td>
126 *         <td></td>
127 *     </tr>
128 *     <tr>
129 *         <td>Cp1124</td>
130 *         <td>?</td>
131 *         <td></td>
132 *     </tr>
133 *     <tr>
134 *         <td>Cp1140</td>
135 *         <td>IBM01140</td>
136 *         <td>CCSID01140 CP01140 ebcdic-us-37+euro </td>
137 *     </tr>
138 *     <tr>
139 *         <td>Cp1141</td>
140 *         <td>IBM01141</td>
141 *         <td>CCSID01141 CP01141 ebcdic-de-273+euro </td>
142 *     </tr>
143 *     <tr>
144 *         <td>Cp1142</td>
145 *         <td>IBM01142</td>
146 *         <td>CCSID01142 CP01142 ebcdic-dk-277+euro ebcdic-no-277+euro </td>
147 *     </tr>
148 *     <tr>
149 *         <td>Cp1143</td>
150 *         <td>IBM01143</td>
151 *         <td>CCSID01143 CP01143 ebcdic-fi-278+euro ebcdic-se-278+euro </td>
152 *     </tr>
153 *     <tr>
154 *         <td>Cp1144</td>
155 *         <td>IBM01144</td>
156 *         <td>CCSID01144 CP01144 ebcdic-it-280+euro </td>
157 *     </tr>
158 *     <tr>
159 *         <td>Cp1145</td>
160 *         <td>IBM01145</td>
161 *         <td>CCSID01145 CP01145 ebcdic-es-284+euro </td>
162 *     </tr>
163 *     <tr>
164 *         <td>Cp1146</td>
165 *         <td>IBM01146</td>
166 *         <td>CCSID01146 CP01146 ebcdic-gb-285+euro </td>
167 *     </tr>
168 *     <tr>
169 *         <td>Cp1147</td>
170 *         <td>IBM01147</td>
171 *         <td>CCSID01147 CP01147 ebcdic-fr-297+euro </td>
172 *     </tr>
173 *     <tr>
174 *         <td>Cp1148</td>
175 *         <td>IBM01148</td>
176 *         <td>CCSID01148 CP01148 ebcdic-international-500+euro </td>
177 *     </tr>
178 *     <tr>
179 *         <td>Cp1149</td>
180 *         <td>IBM01149</td>
181 *         <td>CCSID01149 CP01149 ebcdic-is-871+euro </td>
182 *     </tr>
183 *     <tr>
184 *         <td>Cp1250</td>
185 *         <td>windows-1250</td>
186 *         <td></td>
187 *     </tr>
188 *     <tr>
189 *         <td>Cp1251</td>
190 *         <td>windows-1251</td>
191 *         <td></td>
192 *     </tr>
193 *     <tr>
194 *         <td>Cp1252</td>
195 *         <td>windows-1252</td>
196 *         <td></td>
197 *     </tr>
198 *     <tr>
199 *         <td>Cp1253</td>
200 *         <td>windows-1253</td>
201 *         <td></td>
202 *     </tr>
203 *     <tr>
204 *         <td>Cp1254</td>
205 *         <td>windows-1254</td>
206 *         <td></td>
207 *     </tr>
208 *     <tr>
209 *         <td>Cp1255</td>
210 *         <td>windows-1255</td>
211 *         <td></td>
212 *     </tr>
213 *     <tr>
214 *         <td>Cp1256</td>
215 *         <td>windows-1256</td>
216 *         <td></td>
217 *     </tr>
218 *     <tr>
219 *         <td>Cp1257</td>
220 *         <td>windows-1257</td>
221 *         <td></td>
222 *     </tr>
223 *     <tr>
224 *         <td>Cp1258</td>
225 *         <td>windows-1258</td>
226 *         <td></td>
227 *     </tr>
228 *     <tr>
229 *         <td>Cp1381</td>
230 *         <td>?</td>
231 *         <td></td>
232 *     </tr>
233 *     <tr>
234 *         <td>Cp1383</td>
235 *         <td>?</td>
236 *         <td></td>
237 *     </tr>
238 *     <tr>
239 *         <td>Cp273</td>
240 *         <td>IBM273</td>
241 *         <td>csIBM273 </td>
242 *     </tr>
243 *     <tr>
244 *         <td>Cp277</td>
245 *         <td>IBM277</td>
246 *         <td>EBCDIC-CP-DK EBCDIC-CP-NO csIBM277 </td>
247 *     </tr>
248 *     <tr>
249 *         <td>Cp278</td>
250 *         <td>IBM278</td>
251 *         <td>CP278 ebcdic-cp-fi ebcdic-cp-se csIBM278 </td>
252 *     </tr>
253 *     <tr>
254 *         <td>Cp280</td>
255 *         <td>IBM280</td>
256 *         <td>ebcdic-cp-it csIBM280 </td>
257 *     </tr>
258 *     <tr>
259 *         <td>Cp284</td>
260 *         <td>IBM284</td>
261 *         <td>ebcdic-cp-es csIBM284 </td>
262 *     </tr>
263 *     <tr>
264 *         <td>Cp285</td>
265 *         <td>IBM285</td>
266 *         <td>ebcdic-cp-gb csIBM285 </td>
267 *     </tr>
268 *     <tr>
269 *         <td>Cp297</td>
270 *         <td>IBM297</td>
271 *         <td>ebcdic-cp-fr csIBM297 </td>
272 *     </tr>
273 *     <tr>
274 *         <td>Cp33722</td>
275 *         <td>?</td>
276 *         <td></td>
277 *     </tr>
278 *     <tr>
279 *         <td>Cp420</td>
280 *         <td>IBM420</td>
281 *         <td>ebcdic-cp-ar1 csIBM420 </td>
282 *     </tr>
283 *     <tr>
284 *         <td>Cp424</td>
285 *         <td>IBM424</td>
286 *         <td>ebcdic-cp-he csIBM424 </td>
287 *     </tr>
288 *     <tr>
289 *         <td>Cp437</td>
290 *         <td>IBM437</td>
291 *         <td>437 csPC8CodePage437 </td>
292 *     </tr>
293 *     <tr>
294 *         <td>Cp500</td>
295 *         <td>IBM500</td>
296 *         <td>ebcdic-cp-be ebcdic-cp-ch csIBM500 </td>
297 *     </tr>
298 *     <tr>
299 *         <td>Cp737</td>
300 *         <td>?</td>
301 *         <td></td>
302 *     </tr>
303 *     <tr>
304 *         <td>Cp775</td>
305 *         <td>IBM775</td>
306 *         <td>csPC775Baltic </td>
307 *     </tr>
308 *     <tr>
309 *         <td>Cp838</td>
310 *         <td>IBM-Thai</td>
311 *         <td></td>
312 *     </tr>
313 *     <tr>
314 *         <td>Cp850</td>
315 *         <td>IBM850</td>
316 *         <td>850 csPC850Multilingual </td>
317 *     </tr>
318 *     <tr>
319 *         <td>Cp852</td>
320 *         <td>IBM852</td>
321 *         <td>852 csPCp852 </td>
322 *     </tr>
323 *     <tr>
324 *         <td>Cp855</td>
325 *         <td>IBM855</td>
326 *         <td>855 csIBM855 </td>
327 *     </tr>
328 *     <tr>
329 *         <td>Cp856</td>
330 *         <td>?</td>
331 *         <td></td>
332 *     </tr>
333 *     <tr>
334 *         <td>Cp857</td>
335 *         <td>IBM857</td>
336 *         <td>857 csIBM857 </td>
337 *     </tr>
338 *     <tr>
339 *         <td>Cp858</td>
340 *         <td>IBM00858</td>
341 *         <td>CCSID00858 CP00858 PC-Multilingual-850+euro </td>
342 *     </tr>
343 *     <tr>
344 *         <td>Cp860</td>
345 *         <td>IBM860</td>
346 *         <td>860 csIBM860 </td>
347 *     </tr>
348 *     <tr>
349 *         <td>Cp861</td>
350 *         <td>IBM861</td>
351 *         <td>861 cp-is csIBM861 </td>
352 *     </tr>
353 *     <tr>
354 *         <td>Cp862</td>
355 *         <td>IBM862</td>
356 *         <td>862 csPC862LatinHebrew </td>
357 *     </tr>
358 *     <tr>
359 *         <td>Cp863</td>
360 *         <td>IBM863</td>
361 *         <td>863 csIBM863 </td>
362 *     </tr>
363 *     <tr>
364 *         <td>Cp864</td>
365 *         <td>IBM864</td>
366 *         <td>cp864 csIBM864 </td>
367 *     </tr>
368 *     <tr>
369 *         <td>Cp865</td>
370 *         <td>IBM865</td>
371 *         <td>865 csIBM865 </td>
372 *     </tr>
373 *     <tr>
374 *         <td>Cp866</td>
375 *         <td>IBM866</td>
376 *         <td>866 csIBM866 </td>
377 *     </tr>
378 *     <tr>
379 *         <td>Cp868</td>
380 *         <td>IBM868</td>
381 *         <td>cp-ar csIBM868 </td>
382 *     </tr>
383 *     <tr>
384 *         <td>Cp869</td>
385 *         <td>IBM869</td>
386 *         <td>cp-gr csIBM869 </td>
387 *     </tr>
388 *     <tr>
389 *         <td>Cp870</td>
390 *         <td>IBM870</td>
391 *         <td>ebcdic-cp-roece ebcdic-cp-yu csIBM870 </td>
392 *     </tr>
393 *     <tr>
394 *         <td>Cp871</td>
395 *         <td>IBM871</td>
396 *         <td>ebcdic-cp-is csIBM871 </td>
397 *     </tr>
398 *     <tr>
399 *         <td>Cp875</td>
400 *         <td>?</td>
401 *         <td></td>
402 *     </tr>
403 *     <tr>
404 *         <td>Cp918</td>
405 *         <td>IBM918</td>
406 *         <td>ebcdic-cp-ar2 csIBM918 </td>
407 *     </tr>
408 *     <tr>
409 *         <td>Cp921</td>
410 *         <td>?</td>
411 *         <td></td>
412 *     </tr>
413 *     <tr>
414 *         <td>Cp922</td>
415 *         <td>?</td>
416 *         <td></td>
417 *     </tr>
418 *     <tr>
419 *         <td>Cp930</td>
420 *         <td>?</td>
421 *         <td></td>
422 *     </tr>
423 *     <tr>
424 *         <td>Cp933</td>
425 *         <td>?</td>
426 *         <td></td>
427 *     </tr>
428 *     <tr>
429 *         <td>Cp935</td>
430 *         <td>?</td>
431 *         <td></td>
432 *     </tr>
433 *     <tr>
434 *         <td>Cp937</td>
435 *         <td>?</td>
436 *         <td></td>
437 *     </tr>
438 *     <tr>
439 *         <td>Cp939</td>
440 *         <td>?</td>
441 *         <td></td>
442 *     </tr>
443 *     <tr>
444 *         <td>Cp942</td>
445 *         <td>?</td>
446 *         <td></td>
447 *     </tr>
448 *     <tr>
449 *         <td>Cp942C</td>
450 *         <td>?</td>
451 *         <td></td>
452 *     </tr>
453 *     <tr>
454 *         <td>Cp943</td>
455 *         <td>?</td>
456 *         <td></td>
457 *     </tr>
458 *     <tr>
459 *         <td>Cp943C</td>
460 *         <td>?</td>
461 *         <td></td>
462 *     </tr>
463 *     <tr>
464 *         <td>Cp948</td>
465 *         <td>?</td>
466 *         <td></td>
467 *     </tr>
468 *     <tr>
469 *         <td>Cp949</td>
470 *         <td>?</td>
471 *         <td></td>
472 *     </tr>
473 *     <tr>
474 *         <td>Cp949C</td>
475 *         <td>?</td>
476 *         <td></td>
477 *     </tr>
478 *     <tr>
479 *         <td>Cp950</td>
480 *         <td>?</td>
481 *         <td></td>
482 *     </tr>
483 *     <tr>
484 *         <td>Cp964</td>
485 *         <td>?</td>
486 *         <td></td>
487 *     </tr>
488 *     <tr>
489 *         <td>Cp970</td>
490 *         <td>?</td>
491 *         <td></td>
492 *     </tr>
493 *     <tr>
494 *         <td>EUC_CN</td>
495 *         <td>GB2312</td>
496 *         <td>x-EUC-CN csGB2312 euccn euc-cn gb2312-80 gb2312-1980 CN-GB CN-GB-ISOIR165 </td>
497 *     </tr>
498 *     <tr>
499 *         <td>EUC_JP</td>
500 *         <td>EUC-JP</td>
501 *         <td>csEUCPkdFmtJapanese Extended_UNIX_Code_Packed_Format_for_Japanese eucjis x-eucjp eucjp x-euc-jp </td>
502 *     </tr>
503 *     <tr>
504 *         <td>EUC_JP_LINUX</td>
505 *         <td>?</td>
506 *         <td></td>
507 *     </tr>
508 *     <tr>
509 *         <td>EUC_JP_Solaris</td>
510 *         <td>?</td>
511 *         <td></td>
512 *     </tr>
513 *     <tr>
514 *         <td>EUC_KR</td>
515 *         <td>EUC-KR</td>
516 *         <td>csEUCKR ksc5601 5601 ksc5601_1987 ksc_5601 ksc5601-1987 ks_c_5601-1987 euckr </td>
517 *     </tr>
518 *     <tr>
519 *         <td>EUC_TW</td>
520 *         <td>EUC-TW</td>
521 *         <td>x-EUC-TW cns11643 euctw </td>
522 *     </tr>
523 *     <tr>
524 *         <td>GB18030</td>
525 *         <td>GB18030</td>
526 *         <td>gb18030-2000 </td>
527 *     </tr>
528 *     <tr>
529 *         <td>GBK</td>
530 *         <td>windows-936</td>
531 *         <td>CP936 MS936 ms_936 x-mswin-936 </td>
532 *     </tr>
533 *     <tr>
534 *         <td>ISCII91</td>
535 *         <td>?</td>
536 *         <td>x-ISCII91 iscii </td>
537 *     </tr>
538 *     <tr>
539 *         <td>ISO2022CN</td>
540 *         <td>ISO-2022-CN</td>
541 *         <td></td>
542 *     </tr>
543 *     <tr>
544 *         <td>ISO2022JP</td>
545 *         <td>ISO-2022-JP</td>
546 *         <td>csISO2022JP JIS jis_encoding csjisencoding </td>
547 *     </tr>
548 *     <tr>
549 *         <td>ISO2022KR</td>
550 *         <td>ISO-2022-KR</td>
551 *         <td>csISO2022KR </td>
552 *     </tr>
553 *     <tr>
554 *         <td>ISO2022_CN_CNS</td>
555 *         <td>?</td>
556 *         <td></td>
557 *     </tr>
558 *     <tr>
559 *         <td>ISO2022_CN_GB</td>
560 *         <td>?</td>
561 *         <td></td>
562 *     </tr>
563 *     <tr>
564 *         <td>ISO8859_1</td>
565 *         <td>ISO-8859-1</td>
566 *         <td>ISO_8859-1:1987 iso-ir-100 ISO_8859-1 latin1 l1 IBM819 CP819 csISOLatin1 8859_1 819 IBM-819 ISO8859-1 ISO_8859_1 </td>
567 *     </tr>
568 *     <tr>
569 *         <td>ISO8859_13</td>
570 *         <td>ISO-8859-13</td>
571 *         <td></td>
572 *     </tr>
573 *     <tr>
574 *         <td>ISO8859_15</td>
575 *         <td>ISO-8859-15</td>
576 *         <td>ISO_8859-15 Latin-9 8859_15 csISOlatin9 IBM923 cp923 923 L9 IBM-923 ISO8859-15 LATIN9 LATIN0 csISOlatin0 ISO8859_15_FDIS </td>
577 *     </tr>
578 *     <tr>
579 *         <td>ISO8859_2</td>
580 *         <td>ISO-8859-2</td>
581 *         <td>ISO_8859-2:1987 iso-ir-101 ISO_8859-2 latin2 l2 csISOLatin2 8859_2 iso8859_2 </td>
582 *     </tr>
583 *     <tr>
584 *         <td>ISO8859_3</td>
585 *         <td>ISO-8859-3</td>
586 *         <td>ISO_8859-3:1988 iso-ir-109 ISO_8859-3 latin3 l3 csISOLatin3 8859_3 </td>
587 *     </tr>
588 *     <tr>
589 *         <td>ISO8859_4</td>
590 *         <td>ISO-8859-4</td>
591 *         <td>ISO_8859-4:1988 iso-ir-110 ISO_8859-4 latin4 l4 csISOLatin4 8859_4 </td>
592 *     </tr>
593 *     <tr>
594 *         <td>ISO8859_5</td>
595 *         <td>ISO-8859-5</td>
596 *         <td>ISO_8859-5:1988 iso-ir-144 ISO_8859-5 cyrillic csISOLatinCyrillic 8859_5 </td>
597 *     </tr>
598 *     <tr>
599 *         <td>ISO8859_6</td>
600 *         <td>ISO-8859-6</td>
601 *         <td>ISO_8859-6:1987 iso-ir-127 ISO_8859-6 ECMA-114 ASMO-708 arabic csISOLatinArabic 8859_6 </td>
602 *     </tr>
603 *     <tr>
604 *         <td>ISO8859_7</td>
605 *         <td>ISO-8859-7</td>
606 *         <td>ISO_8859-7:1987 iso-ir-126 ISO_8859-7 ELOT_928 ECMA-118 greek greek8 csISOLatinGreek 8859_7 sun_eu_greek </td>
607 *     </tr>
608 *     <tr>
609 *         <td>ISO8859_8</td>
610 *         <td>ISO-8859-8</td>
611 *         <td>ISO_8859-8:1988 iso-ir-138 ISO_8859-8 hebrew csISOLatinHebrew 8859_8 </td>
612 *     </tr>
613 *     <tr>
614 *         <td>ISO8859_9</td>
615 *         <td>ISO-8859-9</td>
616 *         <td>ISO_8859-9:1989 iso-ir-148 ISO_8859-9 latin5 l5 csISOLatin5 8859_9 </td>
617 *     </tr>
618 *     <tr>
619 *         <td>JISAutoDetect</td>
620 *         <td>?</td>
621 *         <td></td>
622 *     </tr>
623 *     <tr>
624 *         <td>JIS_C6626-1983</td>
625 *         <td>JIS_C6626-1983</td>
626 *         <td>x-JIS0208 JIS0208 csISO87JISX0208 x0208 JIS_X0208-1983 iso-ir-87 </td>
627 *     </tr>
628 *     <tr>
629 *         <td>JIS_X0201</td>
630 *         <td>JIS_X0201</td>
631 *         <td>X0201 JIS0201 csHalfWidthKatakana </td>
632 *     </tr>
633 *     <tr>
634 *         <td>JIS_X0212-1990</td>
635 *         <td>JIS_X0212-1990</td>
636 *         <td>iso-ir-159 x0212 JIS0212 csISO159JISX02121990 </td>
637 *     </tr>
638 *     <tr>
639 *         <td>KOI8_R</td>
640 *         <td>KOI8-R</td>
641 *         <td>csKOI8R koi8 </td>
642 *     </tr>
643 *     <tr>
644 *         <td>MS874</td>
645 *         <td>windows-874</td>
646 *         <td>cp874 </td>
647 *     </tr>
648 *     <tr>
649 *         <td>MS932</td>
650 *         <td>Windows-31J</td>
651 *         <td>windows-932 csWindows31J x-ms-cp932 </td>
652 *     </tr>
653 *     <tr>
654 *         <td>MS949</td>
655 *         <td>windows-949</td>
656 *         <td>windows949 ms_949 x-windows-949 </td>
657 *     </tr>
658 *     <tr>
659 *         <td>MS950</td>
660 *         <td>windows-950</td>
661 *         <td>x-windows-950 </td>
662 *     </tr>
663 *     <tr>
664 *         <td>MS950_HKSCS</td>
665 *         <td></td>
666 *         <td></td>
667 *     </tr>
668 *     <tr>
669 *         <td>MacArabic</td>
670 *         <td>?</td>
671 *         <td></td>
672 *     </tr>
673 *     <tr>
674 *         <td>MacCentralEurope</td>
675 *         <td>?</td>
676 *         <td></td>
677 *     </tr>
678 *     <tr>
679 *         <td>MacCroatian</td>
680 *         <td>?</td>
681 *         <td></td>
682 *     </tr>
683 *     <tr>
684 *         <td>MacCyrillic</td>
685 *         <td>?</td>
686 *         <td></td>
687 *     </tr>
688 *     <tr>
689 *         <td>MacDingbat</td>
690 *         <td>?</td>
691 *         <td></td>
692 *     </tr>
693 *     <tr>
694 *         <td>MacGreek</td>
695 *         <td>MacGreek</td>
696 *         <td></td>
697 *     </tr>
698 *     <tr>
699 *         <td>MacHebrew</td>
700 *         <td>?</td>
701 *         <td></td>
702 *     </tr>
703 *     <tr>
704 *         <td>MacIceland</td>
705 *         <td>?</td>
706 *         <td></td>
707 *     </tr>
708 *     <tr>
709 *         <td>MacRoman</td>
710 *         <td>MacRoman</td>
711 *         <td>Macintosh MAC csMacintosh </td>
712 *     </tr>
713 *     <tr>
714 *         <td>MacRomania</td>
715 *         <td>?</td>
716 *         <td></td>
717 *     </tr>
718 *     <tr>
719 *         <td>MacSymbol</td>
720 *         <td>?</td>
721 *         <td></td>
722 *     </tr>
723 *     <tr>
724 *         <td>MacThai</td>
725 *         <td>?</td>
726 *         <td></td>
727 *     </tr>
728 *     <tr>
729 *         <td>MacTurkish</td>
730 *         <td>?</td>
731 *         <td></td>
732 *     </tr>
733 *     <tr>
734 *         <td>MacUkraine</td>
735 *         <td>?</td>
736 *         <td></td>
737 *     </tr>
738 *     <tr>
739 *         <td>SJIS</td>
740 *         <td>Shift_JIS</td>
741 *         <td>MS_Kanji csShiftJIS shift-jis x-sjis pck </td>
742 *     </tr>
743 *     <tr>
744 *         <td>TIS620</td>
745 *         <td>TIS-620</td>
746 *         <td></td>
747 *     </tr>
748 *     <tr>
749 *         <td>UTF-16</td>
750 *         <td>UTF-16</td>
751 *         <td>UTF_16 </td>
752 *     </tr>
753 *     <tr>
754 *         <td>UTF8</td>
755 *         <td>UTF-8</td>
756 *         <td></td>
757 *     </tr>
758 *     <tr>
759 *         <td>UnicodeBig</td>
760 *         <td>?</td>
761 *         <td></td>
762 *     </tr>
763 *     <tr>
764 *         <td>UnicodeBigUnmarked</td>
765 *         <td>UTF-16BE</td>
766 *         <td>X-UTF-16BE UTF_16BE ISO-10646-UCS-2 </td>
767 *     </tr>
768 *     <tr>
769 *         <td>UnicodeLittle</td>
770 *         <td>?</td>
771 *         <td></td>
772 *     </tr>
773 *     <tr>
774 *         <td>UnicodeLittleUnmarked</td>
775 *         <td>UTF-16LE</td>
776 *         <td>UTF_16LE X-UTF-16LE </td>
777 *     </tr>
778 *     <tr>
779 *         <td>x-Johab</td>
780 *         <td>johab</td>
781 *         <td>johab cp1361 ms1361 ksc5601-1992 ksc5601_1992 </td>
782 *     </tr>
783 *     <tr>
784 *         <td>x-iso-8859-11</td>
785 *         <td>?</td>
786 *         <td></td>
787 *     </tr>
788 * </table>
789 *
790 *
791 * @version $Id: CharsetUtil.java,v 1.1 2004/10/25 07:26:46 ntherning Exp $
792 */
793public class CharsetUtil {
794    private static Log log = LogFactory.getLog(CharsetUtil.class);
795
796    private static class Charset implements Comparable<Charset> {
797        private String canonical = null;
798        private String mime = null;
799        private String[] aliases = null;
800
801        private Charset(String canonical, String mime, String[] aliases) {
802            this.canonical = canonical;
803            this.mime = mime;
804            this.aliases = aliases;
805        }
806
807        public int compareTo(Charset c) {
808            return this.canonical.compareTo(c.canonical);
809        }
810    }
811
812    private static Charset[] JAVA_CHARSETS = {
813        new Charset("ISO8859_1", "ISO-8859-1",
814                    new String[] {"ISO_8859-1:1987", "iso-ir-100", "ISO_8859-1",
815                                  "latin1", "l1", "IBM819", "CP819",
816                                  "csISOLatin1", "8859_1", "819", "IBM-819",
817                                  "ISO8859-1", "ISO_8859_1"}),
818        new Charset("ISO8859_2", "ISO-8859-2",
819                    new String[] {"ISO_8859-2:1987", "iso-ir-101", "ISO_8859-2",
820                                  "latin2", "l2", "csISOLatin2", "8859_2",
821                                  "iso8859_2"}),
822        new Charset("ISO8859_3", "ISO-8859-3", new String[] {"ISO_8859-3:1988", "iso-ir-109", "ISO_8859-3", "latin3", "l3", "csISOLatin3", "8859_3"}),
823        new Charset("ISO8859_4", "ISO-8859-4",
824                    new String[] {"ISO_8859-4:1988", "iso-ir-110", "ISO_8859-4",
825                                  "latin4", "l4", "csISOLatin4", "8859_4"}),
826        new Charset("ISO8859_5", "ISO-8859-5",
827                    new String[] {"ISO_8859-5:1988", "iso-ir-144", "ISO_8859-5",
828                                  "cyrillic", "csISOLatinCyrillic", "8859_5"}),
829        new Charset("ISO8859_6", "ISO-8859-6", new String[] {"ISO_8859-6:1987", "iso-ir-127", "ISO_8859-6", "ECMA-114", "ASMO-708", "arabic", "csISOLatinArabic", "8859_6"}),
830        new Charset("ISO8859_7", "ISO-8859-7",
831                    new String[] {"ISO_8859-7:1987", "iso-ir-126", "ISO_8859-7",
832                                  "ELOT_928", "ECMA-118", "greek", "greek8",
833                                  "csISOLatinGreek", "8859_7", "sun_eu_greek"}),
834        new Charset("ISO8859_8", "ISO-8859-8", new String[] {"ISO_8859-8:1988", "iso-ir-138", "ISO_8859-8", "hebrew", "csISOLatinHebrew", "8859_8"}),
835        new Charset("ISO8859_9", "ISO-8859-9",
836                    new String[] {"ISO_8859-9:1989", "iso-ir-148", "ISO_8859-9",
837                                  "latin5", "l5", "csISOLatin5", "8859_9"}),
838
839        new Charset("ISO8859_13", "ISO-8859-13", new String[] {}),
840        new Charset("ISO8859_15", "ISO-8859-15",
841                    new String[] {"ISO_8859-15", "Latin-9", "8859_15",
842                                  "csISOlatin9", "IBM923", "cp923", "923", "L9",
843                                  "IBM-923", "ISO8859-15", "LATIN9", "LATIN0",
844                                  "csISOlatin0", "ISO8859_15_FDIS"}),
845        new Charset("KOI8_R", "KOI8-R", new String[] {"csKOI8R", "koi8"}),
846        new Charset("ASCII", "US-ASCII",
847                    new String[] {"ANSI_X3.4-1968", "iso-ir-6",
848                                  "ANSI_X3.4-1986", "ISO_646.irv:1991",
849                                  "ISO646-US", "us", "IBM367", "cp367",
850                                  "csASCII", "ascii7", "646", "iso_646.irv:1983"}),
851        new Charset("UTF8", "UTF-8", new String[] {}),
852        new Charset("UTF-16", "UTF-16", new String[] {"UTF_16"}),
853        new Charset("UnicodeBigUnmarked", "UTF-16BE", new String[] {"X-UTF-16BE", "UTF_16BE", "ISO-10646-UCS-2"}),
854        new Charset("UnicodeLittleUnmarked", "UTF-16LE", new String[] {"UTF_16LE", "X-UTF-16LE"}),
855        new Charset("Big5", "Big5", new String[] {"csBig5", "CN-Big5", "BIG-FIVE", "BIGFIVE"}),
856        new Charset("Big5_HKSCS", "Big5-HKSCS", new String[] {"big5hkscs"}),
857        new Charset("EUC_JP", "EUC-JP",
858                    new String[] {"csEUCPkdFmtJapanese",
859                              "Extended_UNIX_Code_Packed_Format_for_Japanese",
860                              "eucjis", "x-eucjp", "eucjp", "x-euc-jp"}),
861        new Charset("EUC_KR", "EUC-KR",
862                    new String[] {"csEUCKR", "ksc5601", "5601", "ksc5601_1987",
863                                  "ksc_5601", "ksc5601-1987", "ks_c_5601-1987",
864                                  "euckr"}),
865        new Charset("GB18030", "GB18030", new String[] {"gb18030-2000"}),
866        new Charset("EUC_CN", "GB2312", new String[] {"x-EUC-CN", "csGB2312", "euccn", "euc-cn", "gb2312-80", "gb2312-1980", "CN-GB", "CN-GB-ISOIR165"}),
867        new Charset("GBK", "windows-936", new String[] {"CP936", "MS936", "ms_936", "x-mswin-936"}),
868
869        new Charset("Cp037", "IBM037", new String[] {"ebcdic-cp-us", "ebcdic-cp-ca", "ebcdic-cp-wt", "ebcdic-cp-nl", "csIBM037"}),
870        new Charset("Cp273", "IBM273", new String[] {"csIBM273"}),
871        new Charset("Cp277", "IBM277", new String[] {"EBCDIC-CP-DK", "EBCDIC-CP-NO", "csIBM277"}),
872        new Charset("Cp278", "IBM278", new String[] {"CP278", "ebcdic-cp-fi", "ebcdic-cp-se", "csIBM278"}),
873        new Charset("Cp280", "IBM280", new String[] {"ebcdic-cp-it", "csIBM280"}),
874        new Charset("Cp284", "IBM284", new String[] {"ebcdic-cp-es", "csIBM284"}),
875        new Charset("Cp285", "IBM285", new String[] {"ebcdic-cp-gb", "csIBM285"}),
876        new Charset("Cp297", "IBM297", new String[] {"ebcdic-cp-fr", "csIBM297"}),
877        new Charset("Cp420", "IBM420", new String[] {"ebcdic-cp-ar1", "csIBM420"}),
878        new Charset("Cp424", "IBM424", new String[] {"ebcdic-cp-he", "csIBM424"}),
879        new Charset("Cp437", "IBM437", new String[] {"437", "csPC8CodePage437"}),
880        new Charset("Cp500", "IBM500", new String[] {"ebcdic-cp-be", "ebcdic-cp-ch", "csIBM500"}),
881        new Charset("Cp775", "IBM775", new String[] {"csPC775Baltic"}),
882        new Charset("Cp838", "IBM-Thai", new String[] {}),
883        new Charset("Cp850", "IBM850", new String[] {"850", "csPC850Multilingual"}),
884        new Charset("Cp852", "IBM852", new String[] {"852", "csPCp852"}),
885        new Charset("Cp855", "IBM855", new String[] {"855", "csIBM855"}),
886        new Charset("Cp857", "IBM857", new String[] {"857", "csIBM857"}),
887        new Charset("Cp858", "IBM00858",
888                new String[] {"CCSID00858", "CP00858",
889                              "PC-Multilingual-850+euro"}),
890        new Charset("Cp860", "IBM860", new String[] {"860", "csIBM860"}),
891        new Charset("Cp861", "IBM861", new String[] {"861", "cp-is", "csIBM861"}),
892        new Charset("Cp862", "IBM862", new String[] {"862", "csPC862LatinHebrew"}),
893        new Charset("Cp863", "IBM863", new String[] {"863", "csIBM863"}),
894        new Charset("Cp864", "IBM864", new String[] {"cp864", "csIBM864"}),
895        new Charset("Cp865", "IBM865", new String[] {"865", "csIBM865"}),
896        new Charset("Cp866", "IBM866", new String[] {"866", "csIBM866"}),
897        new Charset("Cp868", "IBM868", new String[] {"cp-ar", "csIBM868"}),
898        new Charset("Cp869", "IBM869", new String[] {"cp-gr", "csIBM869"}),
899        new Charset("Cp870", "IBM870", new String[] {"ebcdic-cp-roece", "ebcdic-cp-yu", "csIBM870"}),
900        new Charset("Cp871", "IBM871", new String[] {"ebcdic-cp-is", "csIBM871"}),
901        new Charset("Cp918", "IBM918", new String[] {"ebcdic-cp-ar2", "csIBM918"}),
902        new Charset("Cp1026", "IBM1026", new String[] {"csIBM1026"}),
903        new Charset("Cp1047", "IBM1047", new String[] {"IBM-1047"}),
904        new Charset("Cp1140", "IBM01140",
905                    new String[] {"CCSID01140", "CP01140",
906                                  "ebcdic-us-37+euro"}),
907        new Charset("Cp1141", "IBM01141",
908                    new String[] {"CCSID01141", "CP01141",
909                                  "ebcdic-de-273+euro"}),
910        new Charset("Cp1142", "IBM01142", new String[] {"CCSID01142", "CP01142", "ebcdic-dk-277+euro", "ebcdic-no-277+euro"}),
911        new Charset("Cp1143", "IBM01143", new String[] {"CCSID01143", "CP01143", "ebcdic-fi-278+euro", "ebcdic-se-278+euro"}),
912        new Charset("Cp1144", "IBM01144", new String[] {"CCSID01144", "CP01144", "ebcdic-it-280+euro"}),
913        new Charset("Cp1145", "IBM01145", new String[] {"CCSID01145", "CP01145", "ebcdic-es-284+euro"}),
914        new Charset("Cp1146", "IBM01146", new String[] {"CCSID01146", "CP01146", "ebcdic-gb-285+euro"}),
915        new Charset("Cp1147", "IBM01147", new String[] {"CCSID01147", "CP01147", "ebcdic-fr-297+euro"}),
916        new Charset("Cp1148", "IBM01148", new String[] {"CCSID01148", "CP01148", "ebcdic-international-500+euro"}),
917        new Charset("Cp1149", "IBM01149", new String[] {"CCSID01149", "CP01149", "ebcdic-is-871+euro"}),
918        new Charset("Cp1250", "windows-1250", new String[] {}),
919        new Charset("Cp1251", "windows-1251", new String[] {}),
920        new Charset("Cp1252", "windows-1252", new String[] {}),
921        new Charset("Cp1253", "windows-1253", new String[] {}),
922        new Charset("Cp1254", "windows-1254", new String[] {}),
923        new Charset("Cp1255", "windows-1255", new String[] {}),
924        new Charset("Cp1256", "windows-1256", new String[] {}),
925        new Charset("Cp1257", "windows-1257", new String[] {}),
926        new Charset("Cp1258", "windows-1258", new String[] {}),
927        new Charset("ISO2022CN", "ISO-2022-CN", new String[] {}),
928        new Charset("ISO2022JP", "ISO-2022-JP", new String[] {"csISO2022JP", "JIS", "jis_encoding", "csjisencoding"}),
929        new Charset("ISO2022KR", "ISO-2022-KR", new String[] {"csISO2022KR"}),
930        new Charset("JIS_X0201", "JIS_X0201", new String[] {"X0201", "JIS0201", "csHalfWidthKatakana"}),
931        new Charset("JIS_X0212-1990", "JIS_X0212-1990", new String[] {"iso-ir-159", "x0212", "JIS0212", "csISO159JISX02121990"}),
932        new Charset("JIS_C6626-1983", "JIS_C6626-1983", new String[] {"x-JIS0208", "JIS0208", "csISO87JISX0208", "x0208", "JIS_X0208-1983", "iso-ir-87"}),
933        new Charset("SJIS", "Shift_JIS", new String[] {"MS_Kanji", "csShiftJIS", "shift-jis", "x-sjis", "pck"}),
934        new Charset("TIS620", "TIS-620", new String[] {}),
935        new Charset("MS932", "Windows-31J", new String[] {"windows-932", "csWindows31J", "x-ms-cp932"}),
936        new Charset("EUC_TW", "EUC-TW", new String[] {"x-EUC-TW", "cns11643", "euctw"}),
937        new Charset("x-Johab", "johab", new String[] {"johab", "cp1361", "ms1361", "ksc5601-1992", "ksc5601_1992"}),
938        new Charset("MS950_HKSCS", "", new String[] {}),
939        new Charset("MS874", "windows-874", new String[] {"cp874"}),
940        new Charset("MS949", "windows-949", new String[] {"windows949", "ms_949", "x-windows-949"}),
941        new Charset("MS950", "windows-950", new String[] {"x-windows-950"}),
942
943        new Charset("Cp737", null, new String[] {}),
944        new Charset("Cp856", null, new String[] {}),
945        new Charset("Cp875", null, new String[] {}),
946        new Charset("Cp921", null, new String[] {}),
947        new Charset("Cp922", null, new String[] {}),
948        new Charset("Cp930", null, new String[] {}),
949        new Charset("Cp933", null, new String[] {}),
950        new Charset("Cp935", null, new String[] {}),
951        new Charset("Cp937", null, new String[] {}),
952        new Charset("Cp939", null, new String[] {}),
953        new Charset("Cp942", null, new String[] {}),
954        new Charset("Cp942C", null, new String[] {}),
955        new Charset("Cp943", null, new String[] {}),
956        new Charset("Cp943C", null, new String[] {}),
957        new Charset("Cp948", null, new String[] {}),
958        new Charset("Cp949", null, new String[] {}),
959        new Charset("Cp949C", null, new String[] {}),
960        new Charset("Cp950", null, new String[] {}),
961        new Charset("Cp964", null, new String[] {}),
962        new Charset("Cp970", null, new String[] {}),
963        new Charset("Cp1006", null, new String[] {}),
964        new Charset("Cp1025", null, new String[] {}),
965        new Charset("Cp1046", null, new String[] {}),
966        new Charset("Cp1097", null, new String[] {}),
967        new Charset("Cp1098", null, new String[] {}),
968        new Charset("Cp1112", null, new String[] {}),
969        new Charset("Cp1122", null, new String[] {}),
970        new Charset("Cp1123", null, new String[] {}),
971        new Charset("Cp1124", null, new String[] {}),
972        new Charset("Cp1381", null, new String[] {}),
973        new Charset("Cp1383", null, new String[] {}),
974        new Charset("Cp33722", null, new String[] {}),
975        new Charset("Big5_Solaris", null, new String[] {}),
976        new Charset("EUC_JP_LINUX", null, new String[] {}),
977        new Charset("EUC_JP_Solaris", null, new String[] {}),
978        new Charset("ISCII91", null, new String[] {"x-ISCII91", "iscii"}),
979        new Charset("ISO2022_CN_CNS", null, new String[] {}),
980        new Charset("ISO2022_CN_GB", null, new String[] {}),
981        new Charset("x-iso-8859-11", null, new String[] {}),
982        new Charset("JISAutoDetect", null, new String[] {}),
983        new Charset("MacArabic", null, new String[] {}),
984        new Charset("MacCentralEurope", null, new String[] {}),
985        new Charset("MacCroatian", null, new String[] {}),
986        new Charset("MacCyrillic", null, new String[] {}),
987        new Charset("MacDingbat", null, new String[] {}),
988        new Charset("MacGreek", "MacGreek", new String[] {}),
989        new Charset("MacHebrew", null, new String[] {}),
990        new Charset("MacIceland", null, new String[] {}),
991        new Charset("MacRoman", "MacRoman", new String[] {"Macintosh", "MAC", "csMacintosh"}),
992        new Charset("MacRomania", null, new String[] {}),
993        new Charset("MacSymbol", null, new String[] {}),
994        new Charset("MacThai", null, new String[] {}),
995        new Charset("MacTurkish", null, new String[] {}),
996        new Charset("MacUkraine", null, new String[] {}),
997        new Charset("UnicodeBig", null, new String[] {}),
998        new Charset("UnicodeLittle", null, new String[] {})
999    };
1000
1001    /**
1002     * Contains the canonical names of character sets which can be used to
1003     * decode bytes into Java chars.
1004     */
1005    private static TreeSet<String> decodingSupported = null;
1006
1007    /**
1008     * Contains the canonical names of character sets which can be used to
1009     * encode Java chars into bytes.
1010     */
1011    private static TreeSet<String> encodingSupported = null;
1012
1013    /**
1014     * Maps character set names to Charset objects. All possible names of
1015     * a charset will be mapped to the Charset.
1016     */
1017    private static HashMap<String, Charset> charsetMap = null;
1018
1019    static {
1020        decodingSupported = new TreeSet<String>();
1021        encodingSupported = new TreeSet<String>();
1022        byte[] dummy = new byte[] {'d', 'u', 'm', 'm', 'y'};
1023        for (int i = 0; i < JAVA_CHARSETS.length; i++) {
1024            try {
1025                String s = new String(dummy, JAVA_CHARSETS[i].canonical);
1026                decodingSupported.add(JAVA_CHARSETS[i].canonical.toLowerCase());
1027            } catch (UnsupportedOperationException e) {
1028            } catch (UnsupportedEncodingException e) {
1029            }
1030            try {
1031                "dummy".getBytes(JAVA_CHARSETS[i].canonical);
1032                encodingSupported.add(JAVA_CHARSETS[i].canonical.toLowerCase());
1033            } catch (UnsupportedOperationException e) {
1034            } catch (UnsupportedEncodingException e) {
1035            }
1036        }
1037
1038        charsetMap = new HashMap<String, Charset>();
1039        for (int i = 0; i < JAVA_CHARSETS.length; i++) {
1040            Charset c = JAVA_CHARSETS[i];
1041            charsetMap.put(c.canonical.toLowerCase(), c);
1042            if (c.mime != null) {
1043                charsetMap.put(c.mime.toLowerCase(), c);
1044            }
1045            if (c.aliases != null) {
1046                for (int j = 0; j < c.aliases.length; j++) {
1047                    charsetMap.put(c.aliases[j].toLowerCase(), c);
1048                }
1049            }
1050        }
1051
1052        if (log.isDebugEnabled()) {
1053            log.debug("Character sets which support decoding: "
1054                        + decodingSupported);
1055            log.debug("Character sets which support encoding: "
1056                        + encodingSupported);
1057        }
1058    }
1059
1060    /**
1061     * ANDROID:  THE FOLLOWING SET OF STATIC STRINGS ARE COPIED FROM A NEWER VERSION OF MIME4J
1062     */
1063
1064    /** carriage return - line feed sequence */
1065    public static final String CRLF = "\r\n";
1066
1067    /** US-ASCII CR, carriage return (13) */
1068    public static final int CR = '\r';
1069
1070    /** US-ASCII LF, line feed (10) */
1071    public static final int LF = '\n';
1072
1073    /** US-ASCII SP, space (32) */
1074    public static final int SP = ' ';
1075
1076    /** US-ASCII HT, horizontal-tab (9)*/
1077    public static final int HT = '\t';
1078
1079    public static final java.nio.charset.Charset US_ASCII = java.nio.charset.Charset
1080            .forName("US-ASCII");
1081
1082    public static final java.nio.charset.Charset ISO_8859_1 = java.nio.charset.Charset
1083            .forName("ISO-8859-1");
1084
1085    public static final java.nio.charset.Charset UTF_8 = java.nio.charset.Charset
1086            .forName("UTF-8");
1087
1088    /**
1089     * Returns <code>true</code> if the specified character is a whitespace
1090     * character (CR, LF, SP or HT).
1091     *
1092     * ANDROID:  COPIED FROM A NEWER VERSION OF MIME4J
1093     *
1094     * @param ch
1095     *            character to test.
1096     * @return <code>true</code> if the specified character is a whitespace
1097     *         character, <code>false</code> otherwise.
1098     */
1099    public static boolean isWhitespace(char ch) {
1100        return ch == SP || ch == HT || ch == CR || ch == LF;
1101    }
1102
1103    /**
1104     * Returns <code>true</code> if the specified string consists entirely of
1105     * whitespace characters.
1106     *
1107     * ANDROID:  COPIED FROM A NEWER VERSION OF MIME4J
1108     *
1109     * @param s
1110     *            string to test.
1111     * @return <code>true</code> if the specified string consists entirely of
1112     *         whitespace characters, <code>false</code> otherwise.
1113     */
1114    public static boolean isWhitespace(final String s) {
1115        if (s == null) {
1116            throw new IllegalArgumentException("String may not be null");
1117        }
1118        final int len = s.length();
1119        for (int i = 0; i < len; i++) {
1120            if (!isWhitespace(s.charAt(i))) {
1121                return false;
1122            }
1123        }
1124        return true;
1125    }
1126
1127    /**
1128     * Determines if the VM supports encoding (chars to bytes) the
1129     * specified character set. NOTE: the given character set name may
1130     * not be known to the VM even if this method returns <code>true</code>.
1131     * Use {@link #toJavaCharset(String)} to get the canonical Java character
1132     * set name.
1133     *
1134     * @param charsetName the characters set name.
1135     * @return <code>true</code> if encoding is supported, <code>false</code>
1136     *         otherwise.
1137     */
1138    public static boolean isEncodingSupported(String charsetName) {
1139        return encodingSupported.contains(charsetName.toLowerCase());
1140    }
1141
1142    /**
1143     * Determines if the VM supports decoding (bytes to chars) the
1144     * specified character set. NOTE: the given character set name may
1145     * not be known to the VM even if this method returns <code>true</code>.
1146     * Use {@link #toJavaCharset(String)} to get the canonical Java character
1147     * set name.
1148     *
1149     * @param charsetName the characters set name.
1150     * @return <code>true</code> if decoding is supported, <code>false</code>
1151     *         otherwise.
1152     */
1153    public static boolean isDecodingSupported(String charsetName) {
1154        return decodingSupported.contains(charsetName.toLowerCase());
1155    }
1156
1157    /**
1158     * Gets the preferred MIME character set name for the specified
1159     * character set or <code>null</code> if not known.
1160     *
1161     * @param charsetName the character set name to look for.
1162     * @return the MIME preferred name or <code>null</code> if not known.
1163     */
1164    public static String toMimeCharset(String charsetName) {
1165        Charset c = charsetMap.get(charsetName.toLowerCase());
1166        if (c != null) {
1167            return c.mime;
1168        }
1169        return null;
1170    }
1171
1172    /**
1173     * Gets the canonical Java character set name for the specified
1174     * character set or <code>null</code> if not known. This should be
1175     * called before doing any conversions using the Java API. NOTE:
1176     * you must use {@link #isEncodingSupported(String)} or
1177     * {@link #isDecodingSupported(String)} to make sure the returned
1178     * Java character set is supported by the current VM.
1179     *
1180     * @param charsetName the character set name to look for.
1181     * @return the canonical Java name or <code>null</code> if not known.
1182     */
1183    public static String toJavaCharset(String charsetName) {
1184        Charset c = charsetMap.get(charsetName.toLowerCase());
1185        if (c != null) {
1186            return c.canonical;
1187        }
1188        return null;
1189    }
1190
1191    public static java.nio.charset.Charset getCharset(String charsetName) {
1192        String defaultCharset = "ISO-8859-1";
1193
1194        // Use the default chareset if given charset is null
1195        if(charsetName == null) charsetName = defaultCharset;
1196
1197        try {
1198            return java.nio.charset.Charset.forName(charsetName);
1199        } catch (IllegalCharsetNameException e) {
1200            log.info("Illegal charset " + charsetName + ", fallback to " + defaultCharset + ": " + e);
1201            // Use default charset on exception
1202            return java.nio.charset.Charset.forName(defaultCharset);
1203        } catch (UnsupportedCharsetException ex) {
1204            log.info("Unsupported charset " + charsetName + ", fallback to " + defaultCharset + ": " + ex);
1205            // Use default charset on exception
1206            return java.nio.charset.Charset.forName(defaultCharset);
1207        }
1208
1209    }
1210    /*
1211     * Uncomment the code below and run the main method to regenerate the
1212     * Javadoc table above when the known charsets change.
1213     */
1214
1215    /*
1216    private static String dumpHtmlTable() {
1217        LinkedList l = new LinkedList(Arrays.asList(JAVA_CHARSETS));
1218        Collections.sort(l);
1219        StringBuffer sb = new StringBuffer();
1220        sb.append(" * <table>\n");
1221        sb.append(" *     <tr>\n");
1222        sb.append(" *         <td>Canonical (Java) name</td>\n");
1223        sb.append(" *         <td>MIME preferred</td>\n");
1224        sb.append(" *         <td>Aliases</td>\n");
1225        sb.append(" *     </tr>\n");
1226
1227        for (Iterator it = l.iterator(); it.hasNext();) {
1228            Charset c = (Charset) it.next();
1229            sb.append(" *     <tr>\n");
1230            sb.append(" *         <td>" + c.canonical + "</td>\n");
1231            sb.append(" *         <td>" + (c.mime == null ? "?" : c.mime)+ "</td>\n");
1232            sb.append(" *         <td>");
1233            for (int i = 0; c.aliases != null && i < c.aliases.length; i++) {
1234                sb.append(c.aliases[i] + " ");
1235            }
1236            sb.append("</td>\n");
1237            sb.append(" *     </tr>\n");
1238        }
1239        sb.append(" * </table>\n");
1240        return sb.toString();
1241    }
1242
1243    public static void main(String[] args) {
1244        System.out.println(dumpHtmlTable());
1245    }*/
1246}
1247