Hex.java
/*
* 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 java.nio.charset.StandardCharsets;
import org.apache.commons.codec.BinaryDecoder;
import org.apache.commons.codec.BinaryEncoder;
import org.apache.commons.codec.CharEncoding;
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
*/
public class Hex implements BinaryEncoder, BinaryDecoder {
/**
* Default charset is {@link StandardCharsets#UTF_8}.
*
* @since 1.7
*/
public static final Charset DEFAULT_CHARSET = StandardCharsets.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 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 of characters or illegal characters are supplied
*/
public static byte[] decodeHex(final char[] data) throws DecoderException {
final byte[] out = new byte[data.length >> 1];
decodeHex(data, out, 0);
return out;
}
/**
* 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
* @param out A byte array to contain the binary data decoded from the supplied char array.
* @param outOffset The position within {@code out} to start writing the decoded bytes.
* @return the number of bytes written to {@code out}.
* @throws DecoderException Thrown if an odd number of characters or illegal characters are supplied
* @since 1.15
*/
public static int decodeHex(final char[] data, final byte[] out, final int outOffset) throws DecoderException {
final int len = data.length;
if ((len & 0x01) != 0) {
throw new DecoderException("Odd number of characters.");
}
final int outLen = len >> 1;
if (out.length - outOffset < outLen) {
throw new DecoderException("Output array is not large enough to accommodate decoded data.");
}
// two characters form the hex value.
for (int i = outOffset, j = 0; j < len; i++) {
int f = toDigit(data[j], j) << 4;
j++;
f |= toDigit(data[j], j);
j++;
out[i] = (byte) (f & 0xFF);
}
return outLen;
}
/**
* 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 of characters or illegal characters are supplied
* @since 1.11
*/
public static byte[] decodeHex(final String data) throws DecoderException {
return decodeHex(data.toCharArray());
}
/**
* 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 hexadecimal characters
* @return A char[] containing lower-case hexadecimal characters
*/
public static char[] encodeHex(final byte[] 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 {@code true} converts to lowercase, {@code 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, toAlphabet(toLowerCase));
}
/**
* 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 hexadecimal 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 dataLength = data.length;
return encodeHex(data, 0, dataLength, toDigits, new char[dataLength << 1], 0);
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
*
* @param data a byte[] to convert to hexadecimal characters
* @param dataOffset the position in {@code data} to start encoding from
* @param dataLen the number of bytes from {@code dataOffset} to encode
* @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
* @return A char[] containing the appropriate characters from the alphabet For best results, this should be either
* upper- or lower-case hex.
* @since 1.15
*/
public static char[] encodeHex(final byte[] data, final int dataOffset, final int dataLen, final boolean toLowerCase) {
return encodeHex(data, dataOffset, dataLen, toAlphabet(toLowerCase), new char[dataLen << 1], 0);
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
*
* @param data a byte[] to convert to hexadecimal characters
* @param dataOffset the position in {@code data} to start encoding from
* @param dataLen the number of bytes from {@code dataOffset} to encode
* @param toLowerCase {@code true} converts to lowercase, {@code false} to uppercase
* @param out a char[] which will hold the resultant appropriate characters from the alphabet.
* @param outOffset the position within {@code out} at which to start writing the encoded characters.
* @since 1.15
*/
public static void encodeHex(final byte[] data, final int dataOffset, final int dataLen, final boolean toLowerCase, final char[] out, final int outOffset) {
encodeHex(data, dataOffset, dataLen, toAlphabet(toLowerCase), out, outOffset);
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
*
* @param data a byte[] to convert to hexadecimal characters
* @param dataOffset the position in {@code data} to start encoding from
* @param dataLen the number of bytes from {@code dataOffset} to encode
* @param toDigits the output alphabet (must contain at least 16 chars)
* @param out a char[] which will hold the resultant appropriate characters from the alphabet.
* @param outOffset the position within {@code out} at which to start writing the encoded characters.
* @return the given {@code out}.
*/
private static char[] encodeHex(final byte[] data, final int dataOffset, final int dataLen, final char[] toDigits, final char[] out, final int outOffset) {
// two characters form the hex value.
for (int i = dataOffset, j = outOffset; i < dataOffset + dataLen; 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.
*
* <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
* the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
*
* @param data a byte buffer to convert to hexadecimal characters
* @return A char[] containing lower-case hexadecimal characters
* @since 1.11
*/
public static char[] encodeHex(final ByteBuffer 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.
*
* <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
* the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
*
* @param data a byte buffer to convert to hexadecimal characters
* @param toLowerCase {@code true} converts to lowercase, {@code 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, toAlphabet(toLowerCase));
}
/**
* 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.
*
* <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
* the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
*
* @param byteBuffer a byte buffer to convert to hexadecimal 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 byteBuffer, final char[] toDigits) {
return encodeHex(toByteArray(byteBuffer), 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 hexadecimal 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 hexadecimal characters
* @param toLowerCase {@code true} converts to lowercase, {@code 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.
*
* <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
* the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
*
* @param data a byte buffer to convert to hexadecimal 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.
*
* <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
* the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
*
* @param data a byte buffer to convert to hexadecimal characters
* @param toLowerCase {@code true} converts to lowercase, {@code 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 boolean to an alphabet.
*
* @param toLowerCase true for lowercase, false for uppercase.
* @return an alphabet.
*/
private static char[] toAlphabet(final boolean toLowerCase) {
return toLowerCase ? DIGITS_LOWER : DIGITS_UPPER;
}
/**
* Convert the byte buffer to a byte array. All bytes identified by
* {@link ByteBuffer#remaining()} will be used.
*
* @param byteBuffer the byte buffer
* @return the byte[]
*/
private static byte[] toByteArray(final ByteBuffer byteBuffer) {
final int remaining = byteBuffer.remaining();
// Use the underlying buffer if possible
if (byteBuffer.hasArray()) {
final byte[] byteArray = byteBuffer.array();
if (remaining == byteArray.length) {
byteBuffer.position(remaining);
return byteArray;
}
}
// Copy the bytes
final byte[] byteArray = new byte[remaining];
byteBuffer.get(byteArray);
return byteArray;
}
/**
* 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 hexadecimal 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.
*
* <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
* the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
*
* @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(toByteArray(buffer), 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());
}
if (object instanceof byte[]) {
return decode((byte[]) object);
}
if (object instanceof ByteBuffer) {
return decode((ByteBuffer) object);
}
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.
* <p>
* The conversion from hexadecimal characters to the returned bytes is performed with the charset named by
* {@link #getCharset()}.
* </p>
*
* @param array a byte[] to convert to hexadecimal 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.
*
* <p>The conversion from hexadecimal characters to the returned bytes is performed with the charset named by
* {@link #getCharset()}.</p>
*
* <p>All bytes identified by {@link ByteBuffer#remaining()} will be used; after this method
* the value {@link ByteBuffer#remaining() remaining()} will be zero.</p>
*
* @param array a byte buffer to convert to hexadecimal 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.
* <p>
* The conversion from hexadecimal characters to bytes to be encoded to performed with the charset named by
* {@link #getCharset()}.
* </p>
*
* @param object a String, ByteBuffer, or byte[] to convert to hexadecimal 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 {
final byte[] byteArray;
if (object instanceof String) {
byteArray = ((String) object).getBytes(this.getCharset());
} else if (object instanceof ByteBuffer) {
byteArray = toByteArray((ByteBuffer) object);
} 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 + "]";
}
}