Bytes.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.cassandra.cql3.functions.types.utils;
import java.lang.reflect.Constructor;
import java.nio.ByteBuffer;
import java.util.Arrays;
/**
* Simple utility methods to make working with bytes (blob) easier.
*/
public final class Bytes
{
private Bytes()
{
}
private static final byte[] charToByte = new byte[256];
private static final char[] byteToChar = new char[16];
static
{
for (char c = 0; c < charToByte.length; ++c)
{
if (c >= '0' && c <= '9') charToByte[c] = (byte) (c - '0');
else if (c >= 'A' && c <= 'F') charToByte[c] = (byte) (c - 'A' + 10);
else if (c >= 'a' && c <= 'f') charToByte[c] = (byte) (c - 'a' + 10);
else charToByte[c] = (byte) -1;
}
for (int i = 0; i < 16; ++i)
{
byteToChar[i] = Integer.toHexString(i).charAt(0);
}
}
/*
* We use reflexion to get access to a String protected constructor
* (if available) so we can build avoid copy when creating hex strings.
* That's stolen from Cassandra's code.
*/
private static final Constructor<String> stringConstructor;
static
{
Constructor<String> c;
try
{
c = String.class.getDeclaredConstructor(int.class, int.class, char[].class);
c.setAccessible(true);
}
catch (Exception e)
{
c = null;
}
stringConstructor = c;
}
private static String wrapCharArray(char[] c)
{
if (c == null) return null;
String s = null;
if (stringConstructor != null)
{
try
{
s = stringConstructor.newInstance(0, c.length, c);
}
catch (Exception e)
{
// Swallowing as we'll just use a copying constructor
}
}
return s == null ? new String(c) : s;
}
/**
* Converts a blob to its CQL hex string representation.
*
* <p>A CQL blob string representation consist of the hexadecimal representation of the blob bytes
* prefixed by "0x".
*
* @param bytes the blob/bytes to convert to a string.
* @return the CQL string representation of {@code bytes}. If {@code bytes} is {@code null}, this
* method returns {@code null}.
*/
public static String toHexString(ByteBuffer bytes)
{
if (bytes == null) return null;
if (bytes.remaining() == 0) return "0x";
char[] array = new char[2 * (bytes.remaining() + 1)];
array[0] = '0';
array[1] = 'x';
return toRawHexString(bytes, array, 2);
}
/**
* Converts a blob to its CQL hex string representation.
*
* <p>A CQL blob string representation consist of the hexadecimal representation of the blob bytes
* prefixed by "0x".
*
* @param byteArray the blob/bytes array to convert to a string.
* @return the CQL string representation of {@code bytes}. If {@code bytes} is {@code null}, this
* method returns {@code null}.
*/
public static String toHexString(byte[] byteArray)
{
return toHexString(ByteBuffer.wrap(byteArray));
}
/**
* Parse an hex string representing a CQL blob.
*
* <p>The input should be a valid representation of a CQL blob, i.e. it must start by "0x"
* followed by the hexadecimal representation of the blob bytes.
*
* @param str the CQL blob string representation to parse.
* @return the bytes corresponding to {@code str}. If {@code str} is {@code null}, this method
* returns {@code null}.
* @throws IllegalArgumentException if {@code str} is not a valid CQL blob string.
*/
public static ByteBuffer fromHexString(String str)
{
if ((str.length() & 1) == 1)
throw new IllegalArgumentException(
"A CQL blob string must have an even length (since one byte is always 2 hexadecimal character)");
if (str.charAt(0) != '0' || str.charAt(1) != 'x')
throw new IllegalArgumentException("A CQL blob string must start with \"0x\"");
return ByteBuffer.wrap(fromRawHexString(str, 2));
}
/**
* Extract the content of the provided {@code ByteBuffer} as a byte array.
*
* <p>This method work with any type of {@code ByteBuffer} (direct and non-direct ones), but when
* the {@code ByteBuffer} is backed by an array, this method will try to avoid copy when possible.
* As a consequence, changes to the returned byte array may or may not reflect into the initial
* {@code ByteBuffer}.
*
* @param bytes the buffer whose content to extract.
* @return a byte array with the content of {@code bytes}. That array may be the array backing
* {@code bytes} if this can avoid a copy.
*/
public static byte[] getArray(ByteBuffer bytes)
{
int length = bytes.remaining();
if (bytes.hasArray())
{
int boff = bytes.arrayOffset() + bytes.position();
if (boff == 0 && length == bytes.array().length) return bytes.array();
else return Arrays.copyOfRange(bytes.array(), boff, boff + length);
}
// else, DirectByteBuffer.get() is the fastest route
byte[] array = new byte[length];
bytes.duplicate().get(array);
return array;
}
private static String toRawHexString(ByteBuffer bytes, char[] array, int offset)
{
int size = bytes.remaining();
int bytesOffset = bytes.position();
assert array.length >= offset + 2 * size;
for (int i = 0; i < size; i++)
{
int bint = bytes.get(i + bytesOffset);
array[offset + i * 2] = byteToChar[(bint & 0xf0) >> 4];
array[offset + 1 + i * 2] = byteToChar[bint & 0x0f];
}
return wrapCharArray(array);
}
/**
* Converts a CQL hex string representation into a byte array.
*
* <p>A CQL blob string representation consist of the hexadecimal representation of the blob
* bytes.
*
* @param str the string converted in hex representation.
* @param strOffset he offset for starting the string conversion
* @return the byte array which the String was representing.
*/
private static byte[] fromRawHexString(String str, int strOffset)
{
byte[] bytes = new byte[(str.length() - strOffset) / 2];
for (int i = 0; i < bytes.length; i++)
{
byte halfByte1 = charToByte[str.charAt(strOffset + i * 2)];
byte halfByte2 = charToByte[str.charAt(strOffset + i * 2 + 1)];
if (halfByte1 == -1 || halfByte2 == -1)
throw new IllegalArgumentException("Non-hex characters in " + str);
bytes[i] = (byte) ((halfByte1 << 4) | halfByte2);
}
return bytes;
}
}