package com.cloudhopper.commons.util;
/*
* #%L
* ch-commons-util
* %%
* Copyright (C) 2012 Cloudhopper by Twitter
* %%
* 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
*
* 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.
* #L%
*/
/**
* Utility class for encoding or decoding objects to a hexidecimal format.
*
* @author joelauer (twitter: @jjlauer or <a href="http://twitter.com/jjlauer" target=window>http://twitter.com/jjlauer</a>)
*/
public class HexUtil {
public static char[] HEX_TABLE = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};
/**
* Creates a String from a byte array with each byte in a "Big Endian"
* hexidecimal format. For example, a byte 0x34 will return a
* String "34". A byte array of { 0x34, 035 } would return "3435".
* @param buffer The StringBuilder the byte array in hexidecimal format
* will be appended to. If the buffer is null, this method will throw
* a NullPointerException.
* @param bytes The byte array that will be converted to a hexidecimal String.
* If the byte array is null, this method will append nothing (a noop)
*/
public static String toHexString(byte[] bytes) {
if (bytes == null) {
return "";
}
return toHexString(bytes, 0, bytes.length);
}
/**
* Creates a String from a byte array with each byte in a "Big Endian"
* hexidecimal format. For example, a byte 0x34 will return a
* String "34". A byte array of { 0x34, 035 } would return "3435".
* @param buffer The StringBuilder the byte array in hexidecimal format
* will be appended to. If the buffer is null, this method will throw
* a NullPointerException.
* @param bytes The byte array that will be converted to a hexidecimal String.
* If the byte array is null, this method will append nothing (a noop)
* @param offset The offset in the byte array to start from. If the offset
* or length combination is invalid, this method will throw an IllegalArgumentException.
* @param length The length (from the offset) to conver the bytes. If the offset
* or length combination is invalid, this method will throw an IllegalArgumentException.
*/
public static String toHexString(byte[] bytes, int offset, int length) {
if (bytes == null) {
return "";
}
assertOffsetLengthValid(offset, length, bytes.length);
// each byte is 2 chars in string
StringBuilder buffer = new StringBuilder(length * 2);
appendHexString(buffer, bytes, offset, length);
return buffer.toString();
}
/**
* Appends a byte array to a StringBuilder with each byte in a "Big Endian"
* hexidecimal format. For example, a byte 0x34 will be appended as a
* String in format "34". A byte array of { 0x34, 035 } would append "3435".
* @param buffer The StringBuilder the byte array in hexidecimal format
* will be appended to. If the buffer is null, this method will throw
* a NullPointerException.
* @param bytes The byte array that will be converted to a hexidecimal String.
* If the byte array is null, this method will append nothing (a noop)
*/
public static void appendHexString(StringBuilder buffer, byte[] bytes) {
assertNotNull(buffer);
if (bytes == null) {
return; // do nothing (a noop)
}
appendHexString(buffer, bytes, 0, bytes.length);
}
/**
* Appends a byte array to a StringBuilder with each byte in a "Big Endian"
* hexidecimal format. For example, a byte 0x34 will be appended as a
* String in format "34". A byte array of { 0x34, 035 } would append "3435".
* @param buffer The StringBuilder the byte array in hexidecimal format
* will be appended to. If the buffer is null, this method will throw
* a NullPointerException.
* @param bytes The byte array that will be converted to a hexidecimal String.
* If the byte array is null, this method will append nothing (a noop)
* @param offset The offset in the byte array to start from. If the offset
* or length combination is invalid, this method will throw an IllegalArgumentException.
* @param length The length (from the offset) to conver the bytes. If the offset
* or length combination is invalid, this method will throw an IllegalArgumentException.
*/
static public void appendHexString(StringBuilder buffer, byte[] bytes, int offset, int length) {
assertNotNull(buffer);
if (bytes == null) {
return; // do nothing (a noop)
}
assertOffsetLengthValid(offset, length, bytes.length);
int end = offset + length;
for (int i = offset; i < end; i++) {
int nibble1 = (bytes[i] & 0xF0) >>> 4;
int nibble0 = (bytes[i] & 0x0F);
buffer.append(HEX_TABLE[nibble1]);
buffer.append(HEX_TABLE[nibble0]);
}
}
/**
* Creates a 2 character hex String from a byte with the byte in a "Big Endian"
* hexidecimal format. For example, a byte 0x34 will be returned as a
* String in format "34". A byte of value 0 will be returned as "00".
* @param value The byte value that will be converted to a hexidecimal String.
*/
static public String toHexString(byte value) {
StringBuilder buffer = new StringBuilder(2);
appendHexString(buffer, value);
return buffer.toString();
}
/**
* Appends 2 characters to a StringBuilder with the byte in a "Big Endian"
* hexidecimal format. For example, a byte 0x34 will be appended as a
* String in format "34". A byte of value 0 will be appended as "00".
* @param buffer The StringBuilder the byte value in hexidecimal format
* will be appended to. If the buffer is null, this method will throw
* a NullPointerException.
* @param value The byte value that will be converted to a hexidecimal String.
*/
static public void appendHexString(StringBuilder buffer, byte value) {
assertNotNull(buffer);
int nibble = (value & 0xF0) >>> 4;
buffer.append(HEX_TABLE[nibble]);
nibble = (value & 0x0F);
buffer.append(HEX_TABLE[nibble]);
}
/**
* Creates a 4 character hex String from a short with the short in a "Big Endian"
* hexidecimal format. For example, a short 0x1234 will be returned as a
* String in format "1234". A short of value 0 will be returned as "0000".
* @param value The short value that will be converted to a hexidecimal String.
*/
static public String toHexString(short value) {
StringBuilder buffer = new StringBuilder(4);
appendHexString(buffer, value);
return buffer.toString();
}
/**
* Appends 4 characters to a StringBuilder with the short in a "Big Endian"
* hexidecimal format. For example, a short 0x1234 will be appended as a
* String in format "1234". A short of value 0 will be appended as "0000".
* @param buffer The StringBuilder the short value in hexidecimal format
* will be appended to. If the buffer is null, this method will throw
* a NullPointerException.
* @param value The short value that will be converted to a hexidecimal String.
*/
static public void appendHexString(StringBuilder buffer, short value) {
assertNotNull(buffer);
int nibble = (value & 0xF000) >>> 12;
buffer.append(HEX_TABLE[nibble]);
nibble = (value & 0x0F00) >>> 8;
buffer.append(HEX_TABLE[nibble]);
nibble = (value & 0x00F0) >>> 4;
buffer.append(HEX_TABLE[nibble]);
nibble = (value & 0x000F);
buffer.append(HEX_TABLE[nibble]);
}
/**
* Creates an 8 character hex String from an int twith the int in a "Big Endian"
* hexidecimal format. For example, an int 0xFFAA1234 will be returned as a
* String in format "FFAA1234". A int of value 0 will be returned as "00000000".
* @param value The int value that will be converted to a hexidecimal String.
*/
static public String toHexString(int value) {
StringBuilder buffer = new StringBuilder(8);
appendHexString(buffer, value);
return buffer.toString();
}
/**
* Appends 8 characters to a StringBuilder with the int in a "Big Endian"
* hexidecimal format. For example, a int 0xFFAA1234 will be appended as a
* String in format "FFAA1234". A int of value 0 will be appended as "00000000".
* @param buffer The StringBuilder the int value in hexidecimal format
* will be appended to. If the buffer is null, this method will throw
* a NullPointerException.
* @param value The int value that will be converted to a hexidecimal String.
*/
static public void appendHexString(StringBuilder buffer, int value) {
assertNotNull(buffer);
int nibble = (value & 0xF0000000) >>> 28;
buffer.append(HEX_TABLE[nibble]);
nibble = (value & 0x0F000000) >>> 24;
buffer.append(HEX_TABLE[nibble]);
nibble = (value & 0x00F00000) >>> 20;
buffer.append(HEX_TABLE[nibble]);
nibble = (value & 0x000F0000) >>> 16;
buffer.append(HEX_TABLE[nibble]);
nibble = (value & 0x0000F000) >>> 12;
buffer.append(HEX_TABLE[nibble]);
nibble = (value & 0x00000F00) >>> 8;
buffer.append(HEX_TABLE[nibble]);
nibble = (value & 0x000000F0) >>> 4;
buffer.append(HEX_TABLE[nibble]);
nibble = (value & 0x0000000F);
buffer.append(HEX_TABLE[nibble]);
}
/**
* Creates a 16 character hex String from a long with the long in a "Big Endian"
* hexidecimal format. For example, a long 0xAABBCCDDEE123456 will be returned as a
* String in format "AABBCCDDEE123456". A long of value 0 will be returned as "0000000000000000".
* @param value The long value that will be converted to a hexidecimal String.
*/
static public String toHexString(long value) {
StringBuilder buffer = new StringBuilder(16);
appendHexString(buffer, value);
return buffer.toString();
}
/**
* Appends 16 characters to a StringBuilder with the long in a "Big Endian"
* hexidecimal format. For example, a long 0xAABBCCDDEE123456 will be appended as a
* String in format "AABBCCDDEE123456". A long of value 0 will be appended as "0000000000000000".
* @param buffer The StringBuilder the long value in hexidecimal format
* will be appended to. If the buffer is null, this method will throw
* a NullPointerException.
* @param value The long value that will be converted to a hexidecimal String.
*/
static public void appendHexString(StringBuilder buffer, long value) {
appendHexString(buffer, (int)((value & 0xFFFFFFFF00000000L) >>> 32));
appendHexString(buffer, (int)(value & 0x00000000FFFFFFFFL));
}
static private void assertNotNull(StringBuilder buffer) {
if (buffer == null) {
throw new NullPointerException("The buffer cannot be null");
}
}
static private void assertOffsetLengthValid(int offset, int length, int arrayLength) {
if (offset < 0) {
throw new IllegalArgumentException("The array offset was negative");
}
if (length < 0) {
throw new IllegalArgumentException("The array length was negative");
}
if (offset+length > arrayLength) {
throw new ArrayIndexOutOfBoundsException("The array offset+length would access past end of array");
}
}
/**
* Converts a hexidecimal character such as '0' or 'A' or 'a' to its integer
* value such as 0 or 10. Used to decode hexidecimal Strings to integer values.
* @param c The hexidecimal character
* @return The integer value the character represents
* @throws IllegalArgumentException Thrown if a character that does not
* represent a hexidecimal character is used.
*/
static public int hexCharToIntValue(char c) {
if (c == '0') {
return 0;
} else if (c == '1') {
return 1;
} else if (c == '2') {
return 2;
} else if (c == '3') {
return 3;
} else if (c == '4') {
return 4;
} else if (c == '5') {
return 5;
} else if (c == '6') {
return 6;
} else if (c == '7') {
return 7;
} else if (c == '8') {
return 8;
} else if (c == '9') {
return 9;
} else if (c == 'A' || c == 'a') {
return 10;
} else if (c == 'B' || c == 'b') {
return 11;
} else if (c == 'C' || c == 'c') {
return 12;
} else if (c == 'D' || c == 'd') {
return 13;
} else if (c == 'E' || c == 'e') {
return 14;
} else if (c == 'F' || c == 'f') {
return 15;
} else {
throw new IllegalArgumentException("The character [" + c + "] does not represent a valid hex digit");
}
}
/**
* Creates a byte array from a CharSequence (String, StringBuilder, etc.)
* containing only valid hexidecimal formatted characters.
* Each grouping of 2 characters represent a byte in "Big Endian" format.
* The hex CharSequence must be an even length of characters. For example, a String
* of "1234" would return the byte array { 0x12, 0x34 }.
* @param hexString The String, StringBuilder, etc. that contains the
* sequence of hexidecimal character values.
* @return A new byte array representing the sequence of bytes created from
* the sequence of hexidecimal characters. If the hexString is null,
* then this method will return null.
*/
public static byte[] toByteArray(CharSequence hexString) {
if (hexString == null) {
return null;
}
return toByteArray(hexString, 0, hexString.length());
}
/**
* Creates a byte array from a CharSequence (String, StringBuilder, etc.)
* containing only valid hexidecimal formatted characters.
* Each grouping of 2 characters represent a byte in "Big Endian" format.
* The hex CharSequence must be an even length of characters. For example, a String
* of "1234" would return the byte array { 0x12, 0x34 }.
* @param hexString The String, StringBuilder, etc. that contains the
* sequence of hexidecimal character values.
* @param offset The offset within the sequence to start from. If the offset
* is invalid, will cause an IllegalArgumentException.
* @param length The length from the offset to convert. If the length
* is invalid, will cause an IllegalArgumentException.
* @return A new byte array representing the sequence of bytes created from
* the sequence of hexidecimal characters. If the hexString is null,
* then this method will return null.
*/
public static byte[] toByteArray(CharSequence hexString, int offset, int length) {
if (hexString == null) {
return null;
}
assertOffsetLengthValid(offset, length, hexString.length());
// a hex string must be in increments of 2
if ((length % 2) != 0) {
throw new IllegalArgumentException("The hex string did not contain an even number of characters [actual=" + length + "]");
}
// convert hex string to byte array
byte[] bytes = new byte[length/2];
int j = 0;
int end = offset+length;
for (int i = offset; i < end; i += 2) {
int highNibble = hexCharToIntValue(hexString.charAt(i));
int lowNibble = hexCharToIntValue(hexString.charAt(i+1));
bytes[j++] = (byte)(((highNibble << 4) & 0xF0) | (lowNibble & 0x0F));
}
return bytes;
}
}