/**
* Copyright (C) 2012 10gen Inc.
*
* Licensed 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 com.mongodb.util;
/*
* Copyright (C) 2012 10gen Inc.
*
* Licensed 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.
*/
/**
* Provides Base64 encoding and decoding </a>.
*
* <p>
* This class implements Base64 encoding
*
* Thanks to Apache Commons project. This class refactored from org.apache.commons.codec.binary
*
* Original Thanks to "commons" project in ws.apache.org for this code.
* http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
* </p>
*
*/
public class Base64Codec {
private static int BYTES_PER_UNENCODED_BLOCK = 3;
private static int BYTES_PER_ENCODED_BLOCK = 4;
/** Mask used to extract 6 bits, used when encoding */
private static final int SixBitMask = 0x3f;
/** padding char */
private static final byte PAD = '=';
/**
* This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet"
* equivalents as specified in Table 1 of RFC 2045.
*
*/
private static final byte[] EncodeTable = { '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', '+', '/' };
public String encode(byte[] in) {
int modulus = 0;
int bitWorkArea = 0;
int numEncodedBytes = (in.length/BYTES_PER_UNENCODED_BLOCK)*BYTES_PER_ENCODED_BLOCK
+ ((in.length%BYTES_PER_UNENCODED_BLOCK == 0 )?0:4);
byte[] buffer = new byte[numEncodedBytes];
int pos = 0;
for (int i = 0; i < in.length; i++) {
modulus = (modulus+1) % BYTES_PER_UNENCODED_BLOCK;
int b = in[i];
if (b < 0)
b += 256;
bitWorkArea = (bitWorkArea << 8) + b; // BITS_PER_BYTE
if (0 == modulus) { // 3 bytes = 24 bits = 4 * 6 bits to extract
buffer[pos++] = EncodeTable[(bitWorkArea >> 18) & SixBitMask];
buffer[pos++] = EncodeTable[(bitWorkArea >> 12) & SixBitMask];
buffer[pos++] = EncodeTable[(bitWorkArea >> 6) & SixBitMask];
buffer[pos++] = EncodeTable[bitWorkArea & SixBitMask];
}
}
switch (modulus) { // 0-2
case 1 : // 8 bits = 6 + 2
buffer[pos++] = EncodeTable[(bitWorkArea >> 2) & SixBitMask]; // top 6 bits
buffer[pos++] = EncodeTable[(bitWorkArea << 4) & SixBitMask]; // remaining 2
buffer[pos++] = PAD;
buffer[pos++] = PAD;
break;
case 2 : // 16 bits = 6 + 6 + 4
buffer[pos++] = EncodeTable[(bitWorkArea >> 10) & SixBitMask];
buffer[pos++] = EncodeTable[(bitWorkArea >> 4) & SixBitMask];
buffer[pos++] = EncodeTable[(bitWorkArea << 2) & SixBitMask];
buffer[pos++] = PAD;
break;
}
return new String(buffer);
}
}