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With inspiration from other libraries
/*
* 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.commons.codec.binary;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import org.apache.commons.codec.BinaryDecoder;
import org.apache.commons.codec.BinaryEncoder;
import org.apache.commons.codec.CharEncoding;
import org.apache.commons.codec.Charsets;
import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.EncoderException;
/**
* Converts hexadecimal Strings. The charset used for certain operation can be set, the default is set in
* {@link #DEFAULT_CHARSET_NAME}
*
* This class is thread-safe.
*
* @since 1.1
* @version $Id$
*/
public class Hex implements BinaryEncoder, BinaryDecoder {
/**
* Default charset is {@link Charsets#UTF_8}
*
* @since 1.7
*/
public static final Charset DEFAULT_CHARSET = Charsets.UTF_8;
/**
* Default charset name is {@link CharEncoding#UTF_8}
*
* @since 1.4
*/
public static final String DEFAULT_CHARSET_NAME = CharEncoding.UTF_8;
/**
* Used to build output as Hex
*/
private static final char[] DIGITS_LOWER =
{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
/**
* Used to build output as Hex
*/
private static final char[] DIGITS_UPPER =
{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
/**
* Converts a String representing hexadecimal values into an array of bytes of those same values. The
* returned array will be half the length of the passed String, as it takes two characters to represent any given
* byte. An exception is thrown if the passed String has an odd number of elements.
*
* @param data
* A String containing hexadecimal digits
* @return A byte array containing binary data decoded from the supplied char array.
* @throws DecoderException
* Thrown if an odd number or illegal of characters is supplied
* @since 1.11
*/
public static byte[] decodeHex(final String data) throws DecoderException {
return decodeHex(data.toCharArray());
}
/**
* Converts an array of characters representing hexadecimal values into an array of bytes of those same values. The
* returned array will be half the length of the passed array, as it takes two characters to represent any given
* byte. An exception is thrown if the passed char array has an odd number of elements.
*
* @param data
* An array of characters containing hexadecimal digits
* @return A byte array containing binary data decoded from the supplied char array.
* @throws DecoderException
* Thrown if an odd number or illegal of characters is supplied
*/
public static byte[] decodeHex(final char[] data) throws DecoderException {
final int len = data.length;
if ((len & 0x01) != 0) {
throw new DecoderException("Odd number of characters.");
}
final byte[] out = new byte[len >> 1];
// two characters form the hex value.
for (int i = 0, j = 0; j < len; i++) {
int f = toDigit(data[j], j) << 4;
j++;
f = f | toDigit(data[j], j);
j++;
out[i] = (byte) (f & 0xFF);
}
return out;
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
* The returned array will be double the length of the passed array, as it takes two characters to represent any
* given byte.
*
* @param data
* a byte[] to convert to Hex characters
* @return A char[] containing lower-case hexadecimal characters
*/
public static char[] encodeHex(final byte[] data) {
return encodeHex(data, true);
}
/**
* Converts a byte buffer into an array of characters representing the hexadecimal values of each byte in order.
* The returned array will be double the length of the passed array, as it takes two characters to represent any
* given byte.
*
* @param data
* a byte buffer to convert to Hex characters
* @return A char[] containing lower-case hexadecimal characters
* @since 1.11
*/
public static char[] encodeHex(final ByteBuffer data) {
return encodeHex(data, true);
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
* The returned array will be double the length of the passed array, as it takes two characters to represent any
* given byte.
*
* @param data
* a byte[] to convert to Hex characters
* @param toLowerCase
* true converts to lowercase, false to uppercase
* @return A char[] containing hexadecimal characters in the selected case
* @since 1.4
*/
public static char[] encodeHex(final byte[] data, final boolean toLowerCase) {
return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
}
/**
* Converts a byte buffer into an array of characters representing the hexadecimal values of each byte in order.
* The returned array will be double the length of the passed array, as it takes two characters to represent any
* given byte.
*
* @param data
* a byte buffer to convert to Hex characters
* @param toLowerCase
* true converts to lowercase, false to uppercase
* @return A char[] containing hexadecimal characters in the selected case
* @since 1.11
*/
public static char[] encodeHex(final ByteBuffer data, final boolean toLowerCase) {
return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
* The returned array will be double the length of the passed array, as it takes two characters to represent any
* given byte.
*
* @param data
* a byte[] to convert to Hex characters
* @param toDigits
* the output alphabet (must contain at least 16 chars)
* @return A char[] containing the appropriate characters from the alphabet
* For best results, this should be either upper- or lower-case hex.
* @since 1.4
*/
protected static char[] encodeHex(final byte[] data, final char[] toDigits) {
final int l = data.length;
final char[] out = new char[l << 1];
// two characters form the hex value.
for (int i = 0, j = 0; i < l; i++) {
out[j++] = toDigits[(0xF0 & data[i]) >>> 4];
out[j++] = toDigits[0x0F & data[i]];
}
return out;
}
/**
* Converts a byte buffer into an array of characters representing the hexadecimal values of each byte in order.
* The returned array will be double the length of the passed array, as it takes two characters to represent any
* given byte.
*
* @param data
* a byte buffer to convert to Hex characters
* @param toDigits
* the output alphabet (must be at least 16 characters)
* @return A char[] containing the appropriate characters from the alphabet
* For best results, this should be either upper- or lower-case hex.
* @since 1.11
*/
protected static char[] encodeHex(final ByteBuffer data, final char[] toDigits) {
return encodeHex(data.array(), toDigits);
}
/**
* Converts an array of bytes into a String representing the hexadecimal values of each byte in order. The returned
* String will be double the length of the passed array, as it takes two characters to represent any given byte.
*
* @param data
* a byte[] to convert to Hex characters
* @return A String containing lower-case hexadecimal characters
* @since 1.4
*/
public static String encodeHexString(final byte[] data) {
return new String(encodeHex(data));
}
/**
* Converts an array of bytes into a String representing the hexadecimal values of each byte in order. The returned
* String will be double the length of the passed array, as it takes two characters to represent any given byte.
*
* @param data
* a byte[] to convert to Hex characters
* @param toLowerCase
* true converts to lowercase, false to uppercase
* @return A String containing lower-case hexadecimal characters
* @since 1.11
*/
public static String encodeHexString(final byte[] data, final boolean toLowerCase) {
return new String(encodeHex(data, toLowerCase));
}
/**
* Converts a byte buffer into a String representing the hexadecimal values of each byte in order. The returned
* String will be double the length of the passed array, as it takes two characters to represent any given byte.
*
* @param data
* a byte buffer to convert to Hex characters
* @return A String containing lower-case hexadecimal characters
* @since 1.11
*/
public static String encodeHexString(final ByteBuffer data) {
return new String(encodeHex(data));
}
/**
* Converts a byte buffer into a String representing the hexadecimal values of each byte in order. The returned
* String will be double the length of the passed array, as it takes two characters to represent any given byte.
*
* @param data
* a byte buffer to convert to Hex characters
* @param toLowerCase
* true converts to lowercase, false to uppercase
* @return A String containing lower-case hexadecimal characters
* @since 1.11
*/
public static String encodeHexString(final ByteBuffer data, final boolean toLowerCase) {
return new String(encodeHex(data, toLowerCase));
}
/**
* Converts a hexadecimal character to an integer.
*
* @param ch
* A character to convert to an integer digit
* @param index
* The index of the character in the source
* @return An integer
* @throws DecoderException
* Thrown if ch is an illegal hex character
*/
protected static int toDigit(final char ch, final int index) throws DecoderException {
final int digit = Character.digit(ch, 16);
if (digit == -1) {
throw new DecoderException("Illegal hexadecimal character " + ch + " at index " + index);
}
return digit;
}
private final Charset charset;
/**
* Creates a new codec with the default charset name {@link #DEFAULT_CHARSET}
*/
public Hex() {
// use default encoding
this.charset = DEFAULT_CHARSET;
}
/**
* Creates a new codec with the given Charset.
*
* @param charset
* the charset.
* @since 1.7
*/
public Hex(final Charset charset) {
this.charset = charset;
}
/**
* Creates a new codec with the given charset name.
*
* @param charsetName
* the charset name.
* @throws java.nio.charset.UnsupportedCharsetException
* If the named charset is unavailable
* @since 1.4
* @since 1.7 throws UnsupportedCharsetException if the named charset is unavailable
*/
public Hex(final String charsetName) {
this(Charset.forName(charsetName));
}
/**
* Converts an array of character bytes representing hexadecimal values into an array of bytes of those same values.
* The returned array will be half the length of the passed array, as it takes two characters to represent any given
* byte. An exception is thrown if the passed char array has an odd number of elements.
*
* @param array
* An array of character bytes containing hexadecimal digits
* @return A byte array containing binary data decoded from the supplied byte array (representing characters).
* @throws DecoderException
* Thrown if an odd number of characters is supplied to this function
* @see #decodeHex(char[])
*/
@Override
public byte[] decode(final byte[] array) throws DecoderException {
return decodeHex(new String(array, getCharset()).toCharArray());
}
/**
* Converts a buffer of character bytes representing hexadecimal values into an array of bytes of those same values.
* The returned array will be half the length of the passed array, as it takes two characters to represent any given
* byte. An exception is thrown if the passed char array has an odd number of elements.
*
* @param buffer
* An array of character bytes containing hexadecimal digits
* @return A byte array containing binary data decoded from the supplied byte array (representing characters).
* @throws DecoderException
* Thrown if an odd number of characters is supplied to this function
* @see #decodeHex(char[])
* @since 1.11
*/
public byte[] decode(final ByteBuffer buffer) throws DecoderException {
return decodeHex(new String(buffer.array(), getCharset()).toCharArray());
}
/**
* Converts a String or an array of character bytes representing hexadecimal values into an array of bytes of those
* same values. The returned array will be half the length of the passed String or array, as it takes two characters
* to represent any given byte. An exception is thrown if the passed char array has an odd number of elements.
*
* @param object
* A String, ByteBuffer, byte[], or an array of character bytes containing hexadecimal digits
* @return A byte array containing binary data decoded from the supplied byte array (representing characters).
* @throws DecoderException
* Thrown if an odd number of characters is supplied to this function or the object is not a String or
* char[]
* @see #decodeHex(char[])
*/
@Override
public Object decode(final Object object) throws DecoderException {
if (object instanceof String) {
return decode(((String) object).toCharArray());
} else if (object instanceof byte[]) {
return decode((byte[]) object);
} else if (object instanceof ByteBuffer) {
return decode((ByteBuffer) object);
} else {
try {
return decodeHex((char[]) object);
} catch (final ClassCastException e) {
throw new DecoderException(e.getMessage(), e);
}
}
}
/**
* Converts an array of bytes into an array of bytes for the characters representing the hexadecimal values of each
* byte in order. The returned array will be double the length of the passed array, as it takes two characters to
* represent any given byte.
*
* The conversion from hexadecimal characters to the returned bytes is performed with the charset named by
* {@link #getCharset()}.
*
*
* @param array
* a byte[] to convert to Hex characters
* @return A byte[] containing the bytes of the lower-case hexadecimal characters
* @since 1.7 No longer throws IllegalStateException if the charsetName is invalid.
* @see #encodeHex(byte[])
*/
@Override
public byte[] encode(final byte[] array) {
return encodeHexString(array).getBytes(this.getCharset());
}
/**
* Converts byte buffer into an array of bytes for the characters representing the hexadecimal values of each
* byte in order. The returned array will be double the length of the passed array, as it takes two characters to
* represent any given byte.
*
* The conversion from hexadecimal characters to the returned bytes is performed with the charset named by
* {@link #getCharset()}.
*
*
* @param array
* a byte buffer to convert to Hex characters
* @return A byte[] containing the bytes of the lower-case hexadecimal characters
* @see #encodeHex(byte[])
* @since 1.11
*/
public byte[] encode(final ByteBuffer array) {
return encodeHexString(array).getBytes(this.getCharset());
}
/**
* Converts a String or an array of bytes into an array of characters representing the hexadecimal values of each
* byte in order. The returned array will be double the length of the passed String or array, as it takes two
* characters to represent any given byte.
*
* The conversion from hexadecimal characters to bytes to be encoded to performed with the charset named by
* {@link #getCharset()}.
*
*
* @param object
* a String, ByteBuffer, or byte[] to convert to Hex characters
* @return A char[] containing lower-case hexadecimal characters
* @throws EncoderException
* Thrown if the given object is not a String or byte[]
* @see #encodeHex(byte[])
*/
@Override
public Object encode(final Object object) throws EncoderException {
byte[] byteArray;
if (object instanceof String) {
byteArray = ((String) object).getBytes(this.getCharset());
} else if (object instanceof ByteBuffer) {
byteArray = ((ByteBuffer) object).array();
} else {
try {
byteArray = (byte[]) object;
} catch (final ClassCastException e) {
throw new EncoderException(e.getMessage(), e);
}
}
return encodeHex(byteArray);
}
/**
* Gets the charset.
*
* @return the charset.
* @since 1.7
*/
public Charset getCharset() {
return this.charset;
}
/**
* Gets the charset name.
*
* @return the charset name.
* @since 1.4
*/
public String getCharsetName() {
return this.charset.name();
}
/**
* Returns a string representation of the object, which includes the charset name.
*
* @return a string representation of the object.
*/
@Override
public String toString() {
return super.toString() + "[charsetName=" + this.charset + "]";
}
}