/*! ******************************************************************************
*
* Pentaho Data Integration
*
* Copyright (C) 2002-2013 by Pentaho : http://www.pentaho.com
*
*******************************************************************************
*
* 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.
*
******************************************************************************/
package org.pentaho.di.core.util;
import java.security.SecureRandom;
import java.util.Random;
public class UUID4Util {
/** SecureRandom (or Random as failover) used to generate UUID's */
private static Random random;
/** Used to build output as hex. Adapted from org.apache.commons.id.Hex */
private static final char[] DIGITS = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
/**
* Constructor. Initializes random generator, attempting first to use SecureRandom, then failing over to Random.
*/
public UUID4Util() {
try {
random = SecureRandom.getInstance( "SHA1PRNG", "SUN" );
} catch ( Exception e ) {
random = new Random();
}
}
/**
* Generate byte array using random generator. Code adapted from org.apache.commons.id.uuid.VersionFourGenerator.java
*
* @return
*/
private byte[] getBytes() {
byte[] raw = new byte[16];
random.nextBytes( raw );
raw[6] &= 0x0F;
raw[6] |= ( 4 << 4 );
raw[8] &= 0x3F; // 0011 1111
raw[8] |= 0x80; // 1000 0000
return raw;
}
/**
* Turn a byte array into a version four UUID string. Adapted from org.apache.commons.id.uuid.UUID.java
*
* @param raw
* @return
*/
private String getUUIDString( byte[] raw ) {
StringBuilder buf = new StringBuilder( new String( encodeHex( raw ) ) );
while ( buf.length() != 32 ) {
buf.insert( 0, "0" );
}
buf.ensureCapacity( 32 );
buf.insert( 8, '-' );
buf.insert( 13, '-' );
buf.insert( 18, '-' );
buf.insert( 23, '-' );
return buf.toString();
}
/**
* Converts an array of bytes into an array of characters representing the hexidecimal 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.
*
* Adapted from org.apache.commons.id.Hex
*
* @param data
* a byte[] to convert to Hex characters
* @return A char[] containing hexidecimal characters
*/
private static char[] encodeHex( byte[] data ) {
int l = data.length;
char[] out = new char[l << 1];
for ( int i = 0, j = 0; i < l; i++ ) {
out[j++] = DIGITS[( 0xF0 & data[i] ) >>> 4];
out[j++] = DIGITS[0x0F & data[i]];
}
return out;
}
/**
* Generates a string representation of a version four UUID.
*
* @return
*/
public String getUUID4AsString() {
return getUUIDString( getBytes() );
}
}