/**
* 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.hadoop.metrics;
// This code was mostly copied from the Apache Base64 library. We don't link
// with the original Base64 jar, as that jar will not be in the classpaths of
// the client (e.g., HBase) of HDFS. As an unintentional side benefit, the
// implementation here makes minor performance improvements over the original
// since we do not need to be general purpose. In particular, this version
// computes the encoding with single call to a static method. The original
// keeps global state in a Base64 objects and requires multiple calls to an
// instance method.
class SimpleBase64 {
/**
* 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.
*
* Thanks to "commons" project in ws.apache.org for this code.
* http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
*/
private static final byte[] STANDARD_ENCODE_TABLE = {
'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', '+', '/'
};
private static final int BYTES_PER_UNENCODED_BLOCK = 3;
private static final int BYTES_PER_ENCODED_BLOCK = 4;
private static final char PAD = '=';
/**
* Base64 uses 6-bit fields.
*/
/** Mask used to extract 6 bits, used when encoding */
private static final int MASK_6BITS = 0x3f;
public static String encode(byte[] in) throws java.io.UnsupportedEncodingException {
int inLen = in.length;
int padLen = ((BYTES_PER_UNENCODED_BLOCK -
(inLen % BYTES_PER_UNENCODED_BLOCK)) %
BYTES_PER_UNENCODED_BLOCK);
int outLen = (BYTES_PER_ENCODED_BLOCK * (inLen + padLen) /
BYTES_PER_UNENCODED_BLOCK);
byte[] buffer = new byte[outLen];
for (int i=0; i<buffer.length; i++)
buffer[i] = '_';
byte[] encodeTable = STANDARD_ENCODE_TABLE;
int inPos = 0;
int pos = 0;
int bitWorkArea = 0;
int modulus = 0;
int lineLength = 0;
int currentLinePos = 0;
// iterate over main body of the bytes where we can map 3 input bytes to 4
// output bytes
for (int i = 0; i < in.length; i++) {
modulus = (modulus+1) % BYTES_PER_UNENCODED_BLOCK;
int b = in[inPos++];
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) & MASK_6BITS];
buffer[pos++] = encodeTable[(bitWorkArea >> 12) & MASK_6BITS];
buffer[pos++] = encodeTable[(bitWorkArea >> 6) & MASK_6BITS];
buffer[pos++] = encodeTable[bitWorkArea & MASK_6BITS];
}
}
// handle corner case of end of string when it doesn't have an even number
// of bytes
switch (modulus) { // 0-2
case 1 : // 8 bits = 6 + 2
buffer[pos++] = encodeTable[(bitWorkArea >> 2) & MASK_6BITS]; // top 6 bits
buffer[pos++] = encodeTable[(bitWorkArea << 4) & MASK_6BITS]; // remaining 2
// URL-SAFE skips the padding to further reduce size.
if (encodeTable == STANDARD_ENCODE_TABLE) {
buffer[pos++] = PAD;
buffer[pos++] = PAD;
}
break;
case 2 : // 16 bits = 6 + 6 + 4
buffer[pos++] = encodeTable[(bitWorkArea >> 10) & MASK_6BITS];
buffer[pos++] = encodeTable[(bitWorkArea >> 4) & MASK_6BITS];
buffer[pos++] = encodeTable[(bitWorkArea << 2) & MASK_6BITS];
// URL-SAFE skips the padding to further reduce size.
if (encodeTable == STANDARD_ENCODE_TABLE) {
buffer[pos++] = PAD;
}
break;
}
String v = new String(buffer, "UTF-8");
return v;
}
}