/src/ru/adv/util/UniqId.java

/* =================================================================
Copyright (C) 2009 ADV/web-engineering All rights reserved.

This file is part of Mozart.

Mozart is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Mozart is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Foobar.  If not, see <http://www.gnu.org/licenses/>.

Mozart
http://www.mozartcms.ru
================================================================= */
// -*- java -*-
// $Id: UniqId.java 1106 2009-06-03 07:32:17Z vic $
// $Name:  $

package ru.adv.util;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.net.InetAddress;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

/**
 * ????????? ?????????? ???????????????.
 * @version $Revision: 1.6 $
 */
public class UniqId {
	private UniqId() {
	}

	private static SecureRandom seeder;
	private static ByteBuffer midValue = new ByteBuffer();

	static {
		byte[] bytes;
		// get the internet address
		try {
			InetAddress inet = InetAddress.getLocalHost();
			bytes = inet.getAddress();
		}
		catch (java.net.UnknownHostException e) {
			bytes = new byte[4];
		}
		midValue.append(bytes);
		midValue.append(System.identityHashCode(new Object()));
		try {
			byte[] buff = new byte[10];
			BufferedInputStream is = new BufferedInputStream(new FileInputStream("/dev/urandom"));
			Stream.nonBlockRead(is, buff);
			is.close();
			seeder = new SecureRandom(buff);
		}
		catch (Exception e) {
			seeder = new SecureRandom();
		}
		seeder.nextInt();
	}

	private static ByteBuffer getByteBuffer() {
		long timeNow = System.currentTimeMillis();
		// get int value as unsigned int
		int timeLow = (int) (timeNow & 0xFFFFFFFFL);
		// get next random value
		int node = seeder.nextInt();
		return new ByteBuffer(16).append(timeLow).append(midValue).append(node);
	}

	public static String getUUID() {
		return getByteBuffer().toString(16);
	}

	public static String get() {
		try {
			MessageDigest md = MessageDigest.getInstance("MD5");
			return new ByteBuffer(md.digest(getByteBuffer().getBytes()), false).toString(16);
		}
		catch (NoSuchAlgorithmException e) {
			throw new Error(e.getMessage());
		}
	}

	public static void main(String[] argv) {
		long count = 1;
		if (argv.length > 0) {
			count = Long.parseLong(argv[0]);
		}
		for (long i = 0; i < count; i++) {
			System.out.println(get());
		}
	}
}