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 *      http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.tomcat.util.buf;

import org.apache.tomcat.util.res.StringManager;

Tables useful when converting byte arrays to and from strings of hexadecimal digits. Code from Ajp11, from Apache's JServ.
Author:Craig R. McClanahan
/** * Tables useful when converting byte arrays to and from strings of hexadecimal * digits. * Code from Ajp11, from Apache's JServ. * * @author Craig R. McClanahan */
public final class HexUtils { private static final StringManager sm = StringManager.getManager(HexUtils.class); // -------------------------------------------------------------- Constants
Table for HEX to DEC byte translation.
/** * Table for HEX to DEC byte translation. */
private static final int[] DEC = { 00, 01, 02, 03, 04, 05, 06, 07, 8, 9, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, };
Table for DEC to HEX byte translation.
/** * Table for DEC to HEX byte translation. */
private static final byte[] HEX = { (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f' };
Table for byte to hex string translation.
/** * Table for byte to hex string translation. */
private static final char[] hex = "0123456789abcdef".toCharArray(); // --------------------------------------------------------- Static Methods public static int getDec(int index) { // Fast for correct values, slower for incorrect ones try { return DEC[index - '0']; } catch (ArrayIndexOutOfBoundsException ex) { return -1; } } public static byte getHex(int index) { return HEX[index]; } public static String toHexString(byte[] bytes) { if (null == bytes) { return null; } StringBuilder sb = new StringBuilder(bytes.length << 1); for (byte aByte : bytes) { sb.append(hex[(aByte & 0xf0) >> 4]) .append(hex[(aByte & 0x0f)]) ; } return sb.toString(); } public static byte[] fromHexString(String input) { if (input == null) { return null; } if ((input.length() & 1) == 1) { // Odd number of characters throw new IllegalArgumentException(sm.getString("hexUtils.fromHex.oddDigits")); } char[] inputChars = input.toCharArray(); byte[] result = new byte[input.length() >> 1]; for (int i = 0; i < result.length; i++) { int upperNibble = getDec(inputChars[2*i]); int lowerNibble = getDec(inputChars[2*i + 1]); if (upperNibble < 0 || lowerNibble < 0) { // Non hex character throw new IllegalArgumentException(sm.getString("hexUtils.fromHex.nonHex")); } result[i] = (byte) ((upperNibble << 4) + lowerNibble); } return result; } }