Base64public class Base64 extends Object | This class implements Base64 encoding/decoding functionality
as specified in RFC 2045 (http://www.ietf.org/rfc/rfc2045.txt). |
| Fields Summary |
|---|
| private static final byte[] | map |
| Methods Summary |
|---|
| public static byte[] | decode(byte[] in)
return decode(in, in.length);
| | public static byte[] | decode(byte[] in, int len)
// approximate output length
int length = len / 4 * 3;
// return an empty array on emtpy or short input without padding
if (length == 0) {
return new byte[0];
}
// temporary array
byte[] out = new byte[length];
// number of padding characters ('=')
int pad = 0;
byte chr;
// compute the number of the padding characters
// and adjust the length of the input
for (;;len--) {
chr = in[len-1];
// skip the neutral characters
if ((chr == '\n") || (chr == '\r") ||
(chr == ' ") || (chr == '\t")) {
continue;
}
if (chr == '=") {
pad++;
} else {
break;
}
}
// index in the output array
int out_index = 0;
// index in the input array
int in_index = 0;
// holds the value of the input character
int bits = 0;
// holds the value of the input quantum
int quantum = 0;
for (int i=0; i<len; i++) {
chr = in[i];
// skip the neutral characters
if ((chr == '\n") || (chr == '\r") ||
(chr == ' ") || (chr == '\t")) {
continue;
}
if ((chr >= 'A") && (chr <= 'Z")) {
// char ASCII value
// A 65 0
// Z 90 25 (ASCII - 65)
bits = chr - 65;
} else if ((chr >= 'a") && (chr <= 'z")) {
// char ASCII value
// a 97 26
// z 122 51 (ASCII - 71)
bits = chr - 71;
} else if ((chr >= '0") && (chr <= '9")) {
// char ASCII value
// 0 48 52
// 9 57 61 (ASCII + 4)
bits = chr + 4;
} else if (chr == '+") {
bits = 62;
} else if (chr == '/") {
bits = 63;
} else {
return null;
}
// append the value to the quantum
quantum = (quantum << 6) | (byte) bits;
if (in_index%4 == 3) {
// 4 characters were read, so make the output:
out[out_index++] = (byte) ((quantum & 0x00FF0000) >> 16);
out[out_index++] = (byte) ((quantum & 0x0000FF00) >> 8);
out[out_index++] = (byte) (quantum & 0x000000FF);
}
in_index++;
}
if (pad > 0) {
// adjust the quantum value according to the padding
quantum = quantum << (6*pad);
// make output
out[out_index++] = (byte) ((quantum & 0x00FF0000) >> 16);
if (pad == 1) {
out[out_index++] = (byte) ((quantum & 0x0000FF00) >> 8);
}
}
// create the resulting array
byte[] result = new byte[out_index];
System.arraycopy(out, 0, result, 0, out_index);
return result;
| | public static java.lang.String | encode(byte[] in, java.lang.String charsetName)
int length = in.length * 4 / 3;
length += length / 76 + 3; // for crlr
byte[] out = new byte[length];
int index = 0, i, crlr = 0, end = in.length - in.length%3;
for (i=0; i<end; i+=3) {
out[index++] = map[(in[i] & 0xff) >> 2];
out[index++] = map[((in[i] & 0x03) << 4)
| ((in[i+1] & 0xff) >> 4)];
out[index++] = map[((in[i+1] & 0x0f) << 2)
| ((in[i+2] & 0xff) >> 6)];
out[index++] = map[(in[i+2] & 0x3f)];
if (((index - crlr)%76 == 0) && (index != 0)) {
out[index++] = '\n";
crlr++;
//out[index++] = '\r';
//crlr++;
}
}
switch (in.length % 3) {
case 1:
out[index++] = map[(in[end] & 0xff) >> 2];
out[index++] = map[(in[end] & 0x03) << 4];
out[index++] = '=";
out[index++] = '=";
break;
case 2:
out[index++] = map[(in[end] & 0xff) >> 2];
out[index++] = map[((in[end] & 0x03) << 4)
| ((in[end+1] & 0xff) >> 4)];
out[index++] = map[((in[end+1] & 0x0f) << 2)];
out[index++] = '=";
break;
}
return new String(out, 0, index, charsetName);
|
|
