encode Hex
/*
* @(#)$Id: StringUtils.java 3619 2008-03-26 07:23:03Z yui $
*
* Copyright 2006-2008 Makoto YUI
*
* 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.
*
* Contributors:
* Makoto YUI - initial implementation
*/
//package xbird.util.string;
/**
*
* <DIV lang="en"></DIV>
* <DIV lang="ja"></DIV>
*
* @author Makoto YUI (yuin405+xbird@gmail.com)
*/
public final class StringUtils {
private static final char[] HEX_DIGITS = "0123456789ABCDEF".toCharArray();
private static final int UPPER_NIBBLE_MASK = 0xF0;
private static final int LOWER_NIBBLE_MASK = 0x0F;
public static void encodeHex(final byte b, final StringBuilder buf) {
final int upper = (b & UPPER_NIBBLE_MASK) >> 4;
final int lower = b & LOWER_NIBBLE_MASK;
buf.append(HEX_DIGITS[upper]);
buf.append(HEX_DIGITS[lower]);
}
public static String encodeHex(final byte[] buf) {
final int buflen = buf.length;
final char[] ch = new char[buflen * 2];
for(int i = 0, j = 0; i < buf.length; i++, j += 2) {
final byte b = buf[i];
final int upper = (b & UPPER_NIBBLE_MASK) >> 4;
final int lower = b & LOWER_NIBBLE_MASK;
ch[j] = HEX_DIGITS[upper];
ch[j + 1] = HEX_DIGITS[lower];
}
return new String(ch);
}
public static byte[] decodeHex(final char[] data) {
final int len = data.length;
if((len & 0x01) != 0) {
throw new IllegalArgumentException("Illegal HexaDecimal character");
}
final byte[] out = new byte[len >> 1];
for(int i = 0, j = 0; j < len; i++) {
int f = hexToDigit(data[j], j) << 4;
j++;
f = f | hexToDigit(data[j], j);
j++;
out[i] = (byte) (f & 0xFF);
}
return out;
}
private static int hexToDigit(final char ch, final int index) {
final int digit = Character.digit(ch, 16);
if(digit == -1) {
throw new IllegalArgumentException("Illegal HexaDecimal character '" + ch
+ "' at index " + index);
}
return digit;
}
}
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