1 | static byte[] base64decode(String s) {
|
2 | byte[] alphaToInt = base64decode_base64toint; |
3 | int sLen = s.length(); |
4 | int numGroups = sLen/4; |
5 | if (4*numGroups != sLen) |
6 | throw new IllegalArgumentException( |
7 | "String length must be a multiple of four."); |
8 | int missingBytesInLastGroup = 0; |
9 | int numFullGroups = numGroups; |
10 | if (sLen != 0) {
|
11 | if (s.charAt(sLen-1) == '=') {
|
12 | missingBytesInLastGroup++; |
13 | numFullGroups--; |
14 | } |
15 | if (s.charAt(sLen-2) == '=') |
16 | missingBytesInLastGroup++; |
17 | } |
18 | byte[] result = new byte[3*numGroups - missingBytesInLastGroup]; |
19 | |
20 | // Translate all full groups from base64 to byte array elements |
21 | int inCursor = 0, outCursor = 0; |
22 | for (int i=0; i<numFullGroups; i++) {
|
23 | int ch0 = base64decode_base64toint(s.charAt(inCursor++), alphaToInt); |
24 | int ch1 = base64decode_base64toint(s.charAt(inCursor++), alphaToInt); |
25 | int ch2 = base64decode_base64toint(s.charAt(inCursor++), alphaToInt); |
26 | int ch3 = base64decode_base64toint(s.charAt(inCursor++), alphaToInt); |
27 | result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4)); |
28 | result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2)); |
29 | result[outCursor++] = (byte) ((ch2 << 6) | ch3); |
30 | } |
31 | |
32 | // Translate partial group, if present |
33 | if (missingBytesInLastGroup != 0) {
|
34 | int ch0 = base64decode_base64toint(s.charAt(inCursor++), alphaToInt); |
35 | int ch1 = base64decode_base64toint(s.charAt(inCursor++), alphaToInt); |
36 | result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4)); |
37 | |
38 | if (missingBytesInLastGroup == 1) {
|
39 | int ch2 = base64decode_base64toint(s.charAt(inCursor++), alphaToInt); |
40 | result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2)); |
41 | } |
42 | } |
43 | // assert inCursor == s.length()-missingBytesInLastGroup; |
44 | // assert outCursor == result.length; |
45 | return result; |
46 | } |
47 | |
48 | static int base64decode_base64toint(char c, byte[] alphaToInt) {
|
49 | int result = alphaToInt[c]; |
50 | if (result < 0) |
51 | throw new IllegalArgumentException("Illegal character " + c);
|
52 | return result; |
53 | } |
54 | |
55 | static final byte base64decode_base64toint[] = {
|
56 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
57 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
58 | -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, |
59 | 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, |
60 | 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, |
61 | 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, |
62 | 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 |
63 | }; |
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| Snippet ID: | #1001552 |
| Snippet name: | base64decode |
| Eternal ID of this version: | #1001552/1 |
| Text MD5: | 5749ed1ad53e065c0111cd71e62d154b |
| Author: | stefan |
| Category: | javax |
| Type: | JavaX fragment (include) |
| Public (visible to everyone): | Yes |
| Archived (hidden from active list): | No |
| Created/modified: | 2015-10-24 15:32:21 |
| Source code size: | 2717 bytes / 63 lines |
| Pitched / IR pitched: | No / Yes |
| Views / Downloads: | 685 / 1052 |
| Referenced in: | [show references] |