1 public class Base64 {
2 private static char[] base64EncodeChars = new char[] {
3 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
4 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
5 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
6 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
7 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
8 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
9 'w', 'x', 'y', 'z', '0', '1', '2', '3',
10 '4', '5', '6', '7', '8', '9', '+', '/' };
11
12 private static byte[] base64DecodeChars = new byte[] {
13 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
14 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
15 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
16 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
17 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
18 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
19 -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
20 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 };
21
22 Base64() {}
23
24 public static String encode(byte[] data) {
25 StringBuffer sb = new StringBuffer();
26 int len = data.length;
27 int i = 0;
28 int b1, b2, b3;
29
30 while (i < len) {
31 b1 = data[i++] & 0xff;
32 if (i == len) {
33 sb.append(base64EncodeChars[b1 >>> 2]);
34 sb.append(base64EncodeChars[(b1 & 0x3) << 4]);
35 sb.append("==");
36 break;
37 }
38 b2 = data[i++] & 0xff;
39 if (i == len) {
40 sb.append(base64EncodeChars[b1 >>> 2]);
41 sb.append(
42 base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
43 sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);
44 sb.append("=");
45 break;
46 }
47 b3 = data[i++] & 0xff;
48 sb.append(base64EncodeChars[b1 >>> 2]);
49 sb.append(
50 base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
51 sb.append(
52 base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);
53 sb.append(base64EncodeChars[b3 & 0x3f]);
54 }
55 return sb.toString();
56 }
57
58 public static byte[] decode(String str) {
59 byte[] data = str.getBytes();
60 int len = data.length;
61 ByteArrayOutputStream buf = new ByteArrayOutputStream(len);
62 int i = 0;
63 int b1, b2, b3, b4;
64
65 while (i < len) {
66
67 /* b1 */
68 do {
69 b1 = base64DecodeChars[data[i++]];
70 } while (i < len && b1 == -1);
71 if (b1 == -1) {
72 break;
73 }
74
75 /* b2 */
76 do {
77 b2 = base64DecodeChars[data[i++]];
78 } while (i < len && b2 == -1);
79 if (b2 == -1) {
80 break;
81 }
82 buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4)));
83
84 /* b3 */
85 do {
86 b3 = data[i++];
87 if (b3 == 61) {
88 return buf.toByteArray();
89 }
90 b3 = base64DecodeChars[b3];
91 } while (i < len && b3 == -1);
92 if (b3 == -1) {
93 break;
94 }
95 buf.write((int) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));
96
97 /* b4 */
98 do {
99 b4 = data[i++];
100 if (b4 == 61) {
101 return buf.toByteArray();
102 }
103 b4 = base64DecodeChars[b4];
104 } while (i < len && b4 == -1);
105 if (b4 == -1) {
106 break;
107 }
108 buf.write((int) (((b3 & 0x03) << 6) | b4));
109 }
110 return buf.toByteArray();
111 }
112 }
