ID.java

/*
    GNU GENERAL LICENSE
    Copyright (C) 2006 The Lobo Project. Copyright (C) 2014 - 2017 Lobo Evolution

    This program 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
    verion 3 of the License, or (at your option) any later version.

    This program 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 License for more details.

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

    Contact info: lobochief@users.sourceforge.net; ivan.difrancesco@yahoo.it
 */
/*
 * Created on Jun 7, 2005
 */
package org.lobobrowser.util;

import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.net.InetAddress;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Random;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

/**
 * The Class ID.
 *
 * @author J. H. S.
 */
public class ID {
    /** The Constant RANDOM1. */
    private static final Random RANDOM1;
    /** The Constant RANDOM2. */
    private static final Random RANDOM2;
    /** The Constant RANDOM3. */
    private static final Random RANDOM3;
    /** The Constant globalProcessID. */
    private static final long globalProcessID;
    /** The Constant logger. */
    private static final Logger logger = LogManager.getLogger(ID.class);
    
    static {
        long time = System.currentTimeMillis();
        long nanoTime = System.nanoTime();
        long freeMemory = Runtime.getRuntime().freeMemory();
        long addressHashCode;
        try {
            InetAddress inetAddress;
            inetAddress = InetAddress.getLocalHost();
            addressHashCode = inetAddress.getHostName().hashCode()
                    ^ inetAddress.getHostAddress().hashCode();
        } catch (Exception err) {
            logger.error("Unable to get local host information.",
                    err);
            addressHashCode = ID.class.hashCode();
        }
        globalProcessID = time ^ nanoTime ^ freeMemory ^ addressHashCode;
        RANDOM1 = new Random(time);
        RANDOM2 = new Random(nanoTime);
        RANDOM3 = new Random(addressHashCode ^ freeMemory);
    }
    
    /**
     * Instantiates a new id.
     */
    private ID() {
    }
    
    /**
     * Generate long.
     *
     * @return the long
     */
    public static long generateLong() {
        return Math.abs(
                RANDOM1.nextLong() ^ RANDOM2.nextLong() ^ RANDOM3.nextLong());
    }
    
    /**
     * Generate int.
     *
     * @return the int
     */
    public static int generateInt() {
        return (int) generateLong();
    }
    
    /**
     * Gets the m d5 bytes.
     *
     * @param content
     *            the content
     * @return the m d5 bytes
     */
    public static byte[] getMD5Bytes(String content) {
        try {
            MessageDigest digest = MessageDigest.getInstance("MD5");
            return digest.digest(content.getBytes("UTF-8"));
        } catch (NoSuchAlgorithmException e) {
            throw new IllegalStateException(e);
        } catch (UnsupportedEncodingException uee) {
            throw new IllegalStateException(uee);
        }
    }
    
    /**
     * Gets the hex string.
     *
     * @param bytes
     *            the bytes
     * @return the hex string
     */
    public static String getHexString(byte[] bytes) {
        // This method cannot change even if it's wrong.
        BigInteger bigInteger = BigInteger.ZERO;
        int shift = 0;
        for (int i = bytes.length; --i >= 0;) {
            BigInteger contrib = BigInteger.valueOf(bytes[i] & 0xFF);
            contrib = contrib.shiftLeft(shift);
            bigInteger = bigInteger.add(contrib);
            shift += 8;
        }
        return bigInteger.toString(16).toUpperCase();
    }
    
    /** Gets the Constant globalProcessID.
	 *
	 * @return the Constant globalProcessID
	 */
    public static long getGlobalProcessID() {
        return globalProcessID;
    }
    
    /**
     * Random.
     *
     * @param min
     *            the min
     * @param max
     *            the max
     * @return the int
     */
    public static int random(int min, int max) {
        if (max <= min) {
            return min;
        }
        return (Math.abs(RANDOM1.nextInt()) % (max - min)) + min;
    }
}