Java IP Address Get getLocalIP()

Description

Retrieves the IP address of the local computer: - If there exists an interface different from "loopback" it will never return "127.0.0.1" - If there exists multiple network interfaces, the first one will be returned

License

Open Source License

Declaration

public static InetAddress getLocalIP() 

Method Source Code

//package com.java2s;
/*******************************************************************************
 *   /*from  www  .j ava 2s. co  m*/
 *   Copyright 2008 Mytech Ingenieria Aplicada <http://www.mytechia.com>, Gervasio Varela, Alejandro Paz
 *   Victor Sonora
 * 
 *   This file is part of Mytechia Commons.
 *
 *   Mytechia Commons is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   Mytechia Commons 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 Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with Mytechia Commons.  If not, see <http://www.gnu.org/licenses/>.
 * 
 ******************************************************************************/

import java.net.InetAddress;
import java.net.InterfaceAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;

public class Main {
    /**
     * Retrieves the IP address of the local computer:
     * - If there exists an interface different from "loopback" it will never return "127.0.0.1"
     * - If there exists multiple network interfaces, the first one will be returned
     */
    public static InetAddress getLocalIP() {
        try {
            Collection<InterfaceAddress> ips = getAllIPAddresses();
            if (ips.size() > 0) {
                return (InetAddress) ips.iterator().next().getAddress();
            } else {
                return null;
            }
        } catch (Exception e) {
            return null;
        }
    }

    /**
     * Retrieves all the IP addresses of the local computer.
     * The loopback address (127.0.0.1) will not be included.
     */
    public static Collection<InterfaceAddress> getAllIPAddresses() throws SocketException {
        ArrayList<InterfaceAddress> direcciones = new ArrayList();
        InterfaceAddress ipLoopback = null;

        try {
            Enumeration ifaces = NetworkInterface.getNetworkInterfaces();
            while (ifaces.hasMoreElements()) {
                NetworkInterface iface = (NetworkInterface) ifaces.nextElement();
                for (InterfaceAddress ips : iface.getInterfaceAddresses()) {
                    InetAddress ia = ips.getAddress();
                    if (!ia.getHostAddress().contains(":")) {
                        if (ia.isLoopbackAddress()) {
                            ipLoopback = ips;
                        } else {
                            direcciones.add(ips);
                        }
                    }
                }
            }

            if ((direcciones.isEmpty()) && (ipLoopback != null)) {
                direcciones.add(ipLoopback);
            }
        } catch (SocketException e) {
            throw e;
        }

        return direcciones;
    }
}

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