Mega Code Archive
Convert hexadecimal digits into byte array by encoding each two hexadecimal digits as a byte
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/*
* 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.
*/
import java.io.ByteArrayOutputStream;
/**
* Library of utility methods useful in dealing with converting byte arrays to
* and from strings of hexadecimal digits.
*
* @author Craig R. McClanahan
*/
public class Utils {
/**
* Convert a String of hexadecimal digits into the corresponding byte array by
* encoding each two hexadecimal digits as a byte.
*
* @param digits
* Hexadecimal digits representation
*
* @exception IllegalArgumentException
* if an invalid hexadecimal digit is found, or the input string
* contains an odd number of hexadecimal digits
*/
public static byte[] convert(String digits) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
for (int i = 0; i < digits.length(); i += 2) {
char c1 = digits.charAt(i);
if ((i + 1) >= digits.length())
throw new IllegalArgumentException("hexUtil.odd");
char c2 = digits.charAt(i + 1);
byte b = 0;
if ((c1 >= '0') && (c1 <= '9'))
b += ((c1 - '0') * 16);
else if ((c1 >= 'a') && (c1 <= 'f'))
b += ((c1 - 'a' + 10) * 16);
else if ((c1 >= 'A') && (c1 <= 'F'))
b += ((c1 - 'A' + 10) * 16);
else
throw new IllegalArgumentException("hexUtil.bad");
if ((c2 >= '0') && (c2 <= '9'))
b += (c2 - '0');
else if ((c2 >= 'a') && (c2 <= 'f'))
b += (c2 - 'a' + 10);
else if ((c2 >= 'A') && (c2 <= 'F'))
b += (c2 - 'A' + 10);
else
throw new IllegalArgumentException("hexUtil.bad");
baos.write(b);
}
return (baos.toByteArray());
}
}
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