Base64.java

package com.ccx.credit.util;

import java.io.*;

/**
* A class to encode/decode Base64 string/bytes.
* See RFC 1521 section 5.2 for details of the Base64 algorithm.
* Replace Base64 encoder/decoder in org.webmacro.util.Base64
* and com.oreilly.servlet.util.Base64* because they don't handle
* binary correctly (where 8-bit is set).
*/
public class Base64 {
// map 6-bit int to char
private static final char[] chars64 = { 'A', 'B', 'C', 'D', 'E', 'F', 'G',
'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g',
'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6',
'7', '8', '9', '+', '/' };

// map char to 6-bit int
private static final int[] ints64 = new int[128];

static {
for (int i = 0; i < 64; i++) {
ints64[chars64[i]] = i;
}
}

public static final String encode(byte[] unencoded) {
ByteArrayOutputStream out = new ByteArrayOutputStream(
(int) (unencoded.length * 1.37));
int byteCount = 0;
int carryOver = 0;

for (int i = 0; i < unencoded.length; i++) {
int bc = (byteCount % 3);
byte b = unencoded[i];
int lookup = 0;

// First byte use first six bits, save last two bits
if (bc == 0) {
lookup = (b >> 2) & 0x3F;
carryOver = b & 0x03; // last two bits
out.write(chars64[lookup]);
} else if (bc == 1) {
// Second byte use previous two bits and first four new bits,
// save last four bits
lookup = ((carryOver << 4) | ((b >> 4) & 0x0F));
carryOver = b & 0x0F; // last four bits
out.write(chars64[lookup]);
} else if (bc == 2) {
// Third byte use previous four bits and first two new bits,
// then use last six new bits
lookup = ((carryOver << 2) | ((b >> 6) & 0x03));
out.write(chars64[lookup]);

lookup = b & 0x3F; // last six bits
out.write(chars64[lookup]);
carryOver = 0;
}

byteCount++;
}

if ((byteCount % 3) == 1) { // one leftover

int lookup = (carryOver << 4) & 0xF0;
out.write(chars64[lookup]);
out.write('=');
out.write('=');
} else if ((byteCount % 3) == 2) { // two leftovers

int lookup = (carryOver << 2) & 0x3C;
out.write(chars64[lookup]);
out.write('=');
}

return out.toString();
}

public static final byte[] decode(String encoded) {
if (encoded == null || encoded.length() <= 0) {
return null;
}
byte[] bytes = encoded.getBytes();

ByteArrayOutputStream out = new ByteArrayOutputStream(
(int) (bytes.length * 0.67));
int byteCount = 0;
int carryOver = 0;

DECODE_LOOP: for (int i = 0; i < bytes.length; i++) {
int ch = bytes[i];

if (ch == '=') {
break DECODE_LOOP;
}

// Convert from raw form to 6-bit form
int newbits = ints64[ch];

int bc = (byteCount % 4);

if (bc == 0) {
// First char save all six bits, go for another
carryOver = newbits & 0x3F;
} else if (bc == 1) {
// second char use 6 previous bits and first 2 new bits
int data = ((carryOver << 2) + ((newbits >> 4) & 0x03));
out.write(data);
carryOver = newbits & 0x0F; // save 4 bits
} else if (bc == 2) {
// Third char use previous four bits and first four new bits,
// save last two bits
int data = ((carryOver << 4) + ((newbits >> 2) & 0x0F));
out.write(data);
carryOver = newbits & 0x03; // save 2 bits
} else if (bc == 3) {
// Fourth char use previous two bits and all six new bits
int data = ((carryOver << 6) + (newbits & 0x3F));
out.write(data);
carryOver = 0;
}

byteCount++;
}

return out.toByteArray();
}
}