org.apache.openjpa.lib.util.Bytes Maven / Gradle / Ivy
/*
* 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.openjpa.lib.util;
/**
* This class came from the Apache Commons Id sandbox project in support
* of the UUIDGenerator implementation.
*
* Static methods for managing byte arrays (all methods follow Big
* Endian order where most significant bits are in front).
*/
public final class Bytes {
/**
* Hide constructor in utility class.
*/
private Bytes() {
}
/**
* Appends two bytes array into one.
*
* @param a A byte[].
* @param b A byte[].
* @return A byte[].
*/
public static byte[] append(byte[] a, byte[] b) {
byte[] z = new byte[a.length + b.length];
System.arraycopy(a, 0, z, 0, a.length);
System.arraycopy(b, 0, z, a.length, b.length);
return z;
}
/**
* Returns a 8-byte array built from a long.
*
* @param n The number to convert.
* @return A byte[].
*/
public static byte[] toBytes(long n) {
return toBytes(n, new byte[8]);
}
/**
* Build a 8-byte array from a long. No check is performed on the
* array length.
*
* @param n The number to convert.
* @param b The array to fill.
* @return A byte[].
*/
public static byte[] toBytes(long n, byte[] b) {
b[7] = (byte) (n);
n >>>= 8;
b[6] = (byte) (n);
n >>>= 8;
b[5] = (byte) (n);
n >>>= 8;
b[4] = (byte) (n);
n >>>= 8;
b[3] = (byte) (n);
n >>>= 8;
b[2] = (byte) (n);
n >>>= 8;
b[1] = (byte) (n);
n >>>= 8;
b[0] = (byte) (n);
return b;
}
/**
* Build a long from first 8 bytes of the array.
*
* @param b The byte[] to convert.
* @return A long.
*/
public static long toLong(byte[] b) {
return ((((long) b[7]) & 0xFF)
+ ((((long) b[6]) & 0xFF) << 8)
+ ((((long) b[5]) & 0xFF) << 16)
+ ((((long) b[4]) & 0xFF) << 24)
+ ((((long) b[3]) & 0xFF) << 32)
+ ((((long) b[2]) & 0xFF) << 40)
+ ((((long) b[1]) & 0xFF) << 48)
+ ((((long) b[0]) & 0xFF) << 56));
}
/**
* Compares two byte arrays for equality.
*
* @param a A byte[].
* @param b A byte[].
* @return True if the arrays have identical contents.
*/
public static boolean areEqual(byte[] a, byte[] b) {
int aLength = a.length;
if (aLength != b.length) {
return false;
}
for (int i = 0; i < aLength; i++) {
if (a[i] != b[i]) {
return false;
}
}
return true;
}
/**
* Compares two byte arrays as specified by Comparable.
*
* @param lhs - left hand value in the comparison operation.
* @param rhs - right hand value in the comparison operation.
* @return a negative integer, zero, or a positive integer as
* lhs is less than, equal to, or greater than
* rhs.
*/
public static int compareTo(byte[] lhs, byte[] rhs) {
if (lhs == rhs) {
return 0;
}
if (lhs == null) {
return -1;
}
if (rhs == null) {
return +1;
}
if (lhs.length != rhs.length) {
return ((lhs.length < rhs.length) ? -1 : +1);
}
for (int i = 0; i < lhs.length; i++) {
if (lhs[i] < rhs[i]) {
return -1;
} else if (lhs[i] > rhs[i]) {
return 1;
}
}
return 0;
}
/**
* Build a short from first 2 bytes of the array.
*
* @param b The byte[] to convert.
* @return A short.
*/
public static short toShort(byte[] b) {
return (short) ((b[1] & 0xFF) + ((b[0] & 0xFF) << 8));
}
}