com.cedarsoftware.util.ByteUtilities Maven / Gradle / Ivy
/*
* Copyright (c) Cedar Software, LLC
*
* 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
*
* License
*
* 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.cedarsoftware.util;
public final class ByteUtilities
{
private static final char[] _hex =
{
'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};
/**
*
* {@code StringUtilities} instances should NOT be constructed in standard
* programming. Instead, the class should be used statically as
* {@code StringUtilities.trim();}.
*
*/
private ByteUtilities() {
super();
}
// Turn hex String into byte[]
// If string is not even length, return null.
public static byte[] decode(final String s)
{
final int len = s.length();
if (len % 2 != 0)
{
return null;
}
byte[] bytes = new byte[len / 2];
int pos = 0;
for (int i = 0; i < len; i += 2)
{
byte hi = (byte)Character.digit(s.charAt(i), 16);
byte lo = (byte)Character.digit(s.charAt(i + 1), 16);
bytes[pos++] = (byte)(hi * 16 + lo);
}
return bytes;
}
/**
* Convert a byte array into a printable format containing a String of hex
* digit characters (two per byte).
*
* @param bytes array representation
* @return String hex digits
*/
public static String encode(final byte[] bytes)
{
StringBuilder sb = new StringBuilder(bytes.length << 1);
for (byte aByte : bytes)
{
sb.append(convertDigit(aByte >> 4));
sb.append(convertDigit(aByte & 0x0f));
}
return sb.toString();
}
/**
* Convert the specified value (0 .. 15) to the corresponding hex digit.
*
* @param value
* to be converted
* @return '0'..'F' in char format.
*/
private static char convertDigit(final int value)
{
return _hex[value & 0x0f];
}
/**
* @param bytes byte[] of bytes to test
* @return true if bytes are gzip compressed, false otherwise.
*/
public static boolean isGzipped(byte[] bytes)
{
return bytes[0] == (byte)0x1f && bytes[1] == (byte)0x8b;
}
}