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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.apache.tools.ant.util;
/**
* BASE 64 encoding of a String or an array of bytes.
*
* Based on RFC 1421.
*
**/
public class Base64Converter {
private static final int BYTE = 8;
private static final int WORD = 16;
private static final int BYTE_MASK = 0xFF;
private static final int POS_0_MASK = 0x0000003F;
private static final int POS_1_MASK = 0x00000FC0;
private static final int POS_1_SHIFT = 6;
private static final int POS_2_MASK = 0x0003F000;
private static final int POS_2_SHIFT = 12;
private static final int POS_3_MASK = 0x00FC0000;
private static final int POS_3_SHIFT = 18;
private static final char[] ALPHABET = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // 0 to 7
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 8 to 15
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 16 to 23
'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', // 24 to 31
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', // 32 to 39
'o', 'p', 'q', 'r', 's', 't', 'u', 'v', // 40 to 47
'w', 'x', 'y', 'z', '0', '1', '2', '3', // 48 to 55
'4', '5', '6', '7', '8', '9', '+', '/'}; // 56 to 63
// CheckStyle:ConstantNameCheck OFF - bc
/** Provided for BC purposes */
public static final char[] alphabet = ALPHABET;
// CheckStyle:ConstantNameCheck ON
/**
* Encode a string into base64 encoding.
* @param s the string to encode.
* @return the encoded string.
*/
public String encode(String s) {
return encode(s.getBytes());
}
/**
* Encode a byte array into base64 encoding.
* @param octetString the byte array to encode.
* @return the encoded string.
*/
public String encode(byte[] octetString) {
int bits24;
int bits6;
// CheckStyle:MagicNumber OFF
char[] out = new char[((octetString.length - 1) / 3 + 1) * 4];
// CheckStyle:MagicNumber ON
int outIndex = 0;
int i = 0;
// CheckStyle:MagicNumber OFF
while ((i + 3) <= octetString.length) {
// CheckStyle:MagicNumber ON
// store the octets
bits24 = (octetString[i++] & BYTE_MASK) << WORD;
bits24 |= (octetString[i++] & BYTE_MASK) << BYTE;
bits24 |= octetString[i++];
bits6 = (bits24 & POS_3_MASK) >> POS_3_SHIFT;
out[outIndex++] = ALPHABET[bits6];
bits6 = (bits24 & POS_2_MASK) >> POS_2_SHIFT;
out[outIndex++] = ALPHABET[bits6];
bits6 = (bits24 & POS_1_MASK) >> POS_1_SHIFT;
out[outIndex++] = ALPHABET[bits6];
bits6 = (bits24 & POS_0_MASK);
out[outIndex++] = ALPHABET[bits6];
}
if (octetString.length - i == 2) {
// store the octets
bits24 = (octetString[i] & BYTE_MASK) << WORD;
bits24 |= (octetString[i + 1] & BYTE_MASK) << BYTE;
bits6 = (bits24 & POS_3_MASK) >> POS_3_SHIFT;
out[outIndex++] = ALPHABET[bits6];
bits6 = (bits24 & POS_2_MASK) >> POS_2_SHIFT;
out[outIndex++] = ALPHABET[bits6];
bits6 = (bits24 & POS_1_MASK) >> POS_1_SHIFT;
out[outIndex++] = ALPHABET[bits6];
// padding
out[outIndex++] = '=';
} else if (octetString.length - i == 1) {
// store the octets
bits24 = (octetString[i] & BYTE_MASK) << WORD;
bits6 = (bits24 & POS_3_MASK) >> POS_3_SHIFT;
out[outIndex++] = ALPHABET[bits6];
bits6 = (bits24 & POS_2_MASK) >> POS_2_SHIFT;
out[outIndex++] = ALPHABET[bits6];
// padding
out[outIndex++] = '=';
out[outIndex++] = '=';
}
return new String(out);
}
}