Convert a TCP/IP address string into a byte array : Byte Array « File Input Output « Java

Convert a TCP/IP address string into a byte array

 * Copyright (C) 2006-2008 Alfresco Software Limited.
 * 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 version 2
 * 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
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 * As a special exception to the terms and conditions of version 2.0 of 
 * the GPL, you may redistribute this Program in connection with Free/Libre 
 * and Open Source Software ("FLOSS") applications as described in Alfresco's 
 * FLOSS exception.  You should have recieved a copy of the text describing 
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//package net.gqu.utils;

import java.util.StringTokenizer;

 * TCP/IP Address Utility Class
 * @author gkspencer
public class IPAddress {

     * Convert a TCP/IP address string into a byte array
     * @param addr String
     * @return byte[]
    public final static byte[] asBytes(String addr) {
      // Convert the TCP/IP address string to an integer value
      int ipInt = parseNumericAddress(addr);
      if ( ipInt == 0)
        return null;
      // Convert to bytes
      byte[] ipByts = new byte[4];
      ipByts[3] = (byte) (ipInt & 0xFF);
      ipByts[2] = (byte) ((ipInt >> 8) & 0xFF);
      ipByts[1] = (byte) ((ipInt >> 16) & 0xFF);
      ipByts[0] = (byte) ((ipInt >> 24) & 0xFF);
      // Return the TCP/IP bytes
      return ipByts;
   * Check if the specified address is a valid numeric TCP/IP address and return as an integer value
   * @param ipaddr String
   * @return int
  public final static int parseNumericAddress(String ipaddr) {
    //  Check if the string is valid
    if ( ipaddr == null || ipaddr.length() < 7 || ipaddr.length() > 15)
      return 0;
    //  Check the address string, should be n.n.n.n format
    StringTokenizer token = new StringTokenizer(ipaddr,".");
    if ( token.countTokens() != 4)
      return 0;

    int ipInt = 0;
    while ( token.hasMoreTokens()) {
      //  Get the current token and convert to an integer value
      String ipNum = token.nextToken();
      try {
        //  Validate the current address part
        int ipVal = Integer.valueOf(ipNum).intValue();
        if ( ipVal < 0 || ipVal > 255)
          return 0;
        //  Add to the integer address
        ipInt = (ipInt << 8) + ipVal;
      catch (NumberFormatException ex) {
        return 0;
    //  Return the integer address
    return ipInt;



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