Java IP Address Get getIPFromNetworkInterface()

Description

Returns the IP address determined from the network interfaces (using the IP address of the one with a proper host name).

License

Open Source License

Return

the IP address

Declaration

public static synchronized String getIPFromNetworkInterface() 

Method Source Code

//package com.java2s;
/*/*from   w  w  w. j ava 2s .c o  m*/
 *   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 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 Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

public class Main {
    /** IP (from network intf) for faster access. */
    protected static String m_IPNetworkInterface;

    /**
     * Returns the IP address determined from the network interfaces (using
     * the IP address of the one with a proper host name).
     *
     * @return       the IP address
     */
    public static synchronized String getIPFromNetworkInterface() {
        String result;
        List<String> list;
        Enumeration<NetworkInterface> enmI;
        NetworkInterface intf;
        Enumeration<InetAddress> enmA;
        InetAddress addr;
        boolean found;

        result = null;

        if (m_IPNetworkInterface == null) {
            list = new ArrayList<>();
            found = false;
            try {
                enmI = NetworkInterface.getNetworkInterfaces();
                while (enmI.hasMoreElements()) {
                    intf = enmI.nextElement();
                    // skip non-active ones
                    if (!intf.isUp())
                        continue;
                    enmA = intf.getInetAddresses();
                    while (enmA.hasMoreElements()) {
                        addr = enmA.nextElement();
                        list.add(addr.getHostAddress());
                        if (addr.getHostName().indexOf(':') == -1) {
                            result = addr.getHostAddress();
                            found = true;
                            break;
                        }
                    }
                    if (found)
                        break;
                }
            } catch (Exception e) {
                // ignored
            }

            if (result == null) {
                if (list.size() > 0)
                    result = list.get(0);
                else
                    result = "<unknown>";
            }

            m_IPNetworkInterface = result;
        } else {
            result = m_IPNetworkInterface;
        }

        return result;
    }
}

Related

1. getIPByInterfaceName(String name)
2. getIpByName(String name)
3. getIpByNetworkInterfaceName(String name)
4. getIPFromHash(final long ipHash)
5. getIPFromInterface(String ni)
6. getIpHostnameLocal()
7. getIPList(String address)
8. getIPList(String s, String s1)
9. getIPs()