Uzyskiwanie adresu IP bieżącej maszyny za pomocą Java

To może być trochę trudne w najbardziej ogólnym przypadku.

Na pierwszy rzut oka, InetAddress.getLocalHost() powinien podać adres IP tego hosta. Problem polega na tym, że host może mieć wiele interfejsów sieciowych, a interfejs może być związany z więcej niż jednym adresem IP. Co więcej, nie wszystkie adresy IP będą dostępne poza Twoim komputerem lub siecią LAN. Mogą to być na przykład adresy IP dla wirtualnych urządzeń sieciowych, adresy IP sieci prywatnej itd.

Co to oznacza to, że adres IP zwracany przez InetAddress.getLocalHost() może nie być odpowiedni do użycia.

• jednym z sposobów jest użycie NetworkInterface.getNetworkInterfaces(), aby uzyskać wszystkie znane interfejsy sieciowe na hoście, a następnie iterację nad każdym adresem NI.
• innym podejściem jest (w jakiś sposób) uzyskanie zewnętrznie reklamowanego FQDN dla hosta i użycie InetAddress.getByName() do wyszukania głównego adresu IP. (Ale jak to uzyskać i jak radzić sobie z obciążeniem opartym na DNS balancer?)
• odmianą poprzedniej jest pobranie preferowanego FQDN z pliku konfiguracyjnego lub parametru wiersza poleceń.
• inną odmianą jest pobranie preferowanego adresu IP z pliku konfiguracyjnego lub parametru wiersza poleceń.

Podsumowując, InetAddress.getLocalHost() Zazwyczaj będzie działać, ale być może będziesz musiał podać alternatywną metodę w przypadkach, gdy twój kod jest uruchamiany w środowisku o "skomplikowanej" sieci.

Jestem w stanie uzyskać wszystkie adresy IP kojarzy wszystkie interfejsy sieciowe, ale jak je odróżnić?

• dowolny adres z zakresu 127.xxx. xxx. xxx To Adres "loopback". Jest widoczny tylko dla" tego " gospodarza.
• dowolny adres z zakresu 192.168.xxx. xxx to prywatny (aka lokalny) adres IP. Są one zarezerwowane do użytku w organizacji. To samo dotyczy 10.adresy xxx. xxx. xxx oraz 172.16.xxx. xxx do 172.31xxx. xxx.
• adresy z zakresu 169.254.xxx. xxx to link lokalny Adresy IP. Są one zarezerwowane do użytku w jednym segmencie sieci.
• adresy z zakresu 224.xxx. xxx. XXX do 239.xxx. xxx. xxx to adresy multicastowe.
• adres 255.255.255.255 jest adresem nadawcy.
• cokolwiek innegopowinno być poprawnym publicznym adresem IPv4 typu point-to-point.

W rzeczywistości, InetAddress API dostarcza metody do testowania dla loopback, link local, site local, multicast i broadcast adresów. Możesz użyć tych aby uporządkować, który z adresów IP otrzymasz z powrotem, jest najbardziej odpowiedni.

Zamieszczanie tutaj sprawdzonego kodu obejścia niejasności IP z https://issues.apache.org/jira/browse/JCS-40 (InetAddress.getLocalHost () na systemach Linux):

/**
 * Returns an <code>InetAddress</code> object encapsulating what is most likely the machine's LAN IP address.
 * <p/>
 * This method is intended for use as a replacement of JDK method <code>InetAddress.getLocalHost</code>, because
 * that method is ambiguous on Linux systems. Linux systems enumerate the loopback network interface the same
 * way as regular LAN network interfaces, but the JDK <code>InetAddress.getLocalHost</code> method does not
 * specify the algorithm used to select the address returned under such circumstances, and will often return the
 * loopback address, which is not valid for network communication. Details
 * <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4665037">here</a>.
 * <p/>
 * This method will scan all IP addresses on all network interfaces on the host machine to determine the IP address
 * most likely to be the machine's LAN address. If the machine has multiple IP addresses, this method will prefer
 * a site-local IP address (e.g. 192.168.x.x or 10.10.x.x, usually IPv4) if the machine has one (and will return the
 * first site-local address if the machine has more than one), but if the machine does not hold a site-local
 * address, this method will return simply the first non-loopback address found (IPv4 or IPv6).
 * <p/>
 * If this method cannot find a non-loopback address using this selection algorithm, it will fall back to
 * calling and returning the result of JDK method <code>InetAddress.getLocalHost</code>.
 * <p/>
 *
 * @throws UnknownHostException If the LAN address of the machine cannot be found.
 */
private static InetAddress getLocalHostLANAddress() throws UnknownHostException {
    try {
        InetAddress candidateAddress = null;
        // Iterate all NICs (network interface cards)...
        for (Enumeration ifaces = NetworkInterface.getNetworkInterfaces(); ifaces.hasMoreElements();) {
            NetworkInterface iface = (NetworkInterface) ifaces.nextElement();
            // Iterate all IP addresses assigned to each card...
            for (Enumeration inetAddrs = iface.getInetAddresses(); inetAddrs.hasMoreElements();) {
                InetAddress inetAddr = (InetAddress) inetAddrs.nextElement();
                if (!inetAddr.isLoopbackAddress()) {

                    if (inetAddr.isSiteLocalAddress()) {
                        // Found non-loopback site-local address. Return it immediately...
                        return inetAddr;
                    }
                    else if (candidateAddress == null) {
                        // Found non-loopback address, but not necessarily site-local.
                        // Store it as a candidate to be returned if site-local address is not subsequently found...
                        candidateAddress = inetAddr;
                        // Note that we don't repeatedly assign non-loopback non-site-local addresses as candidates,
                        // only the first. For subsequent iterations, candidate will be non-null.
                    }
                }
            }
        }
        if (candidateAddress != null) {
            // We did not find a site-local address, but we found some other non-loopback address.
            // Server might have a non-site-local address assigned to its NIC (or it might be running
            // IPv6 which deprecates the "site-local" concept).
            // Return this non-loopback candidate address...
            return candidateAddress;
        }
        // At this point, we did not find a non-loopback address.
        // Fall back to returning whatever InetAddress.getLocalHost() returns...
        InetAddress jdkSuppliedAddress = InetAddress.getLocalHost();
        if (jdkSuppliedAddress == null) {
            throw new UnknownHostException("The JDK InetAddress.getLocalHost() method unexpectedly returned null.");
        }
        return jdkSuppliedAddress;
    }
    catch (Exception e) {
        UnknownHostException unknownHostException = new UnknownHostException("Failed to determine LAN address: " + e);
        unknownHostException.initCause(e);
        throw unknownHostException;
    }
}

Możesz użyć w tym celu klasy java InetAddress.

InetAddress IP=InetAddress.getLocalHost();
System.out.println("IP of my system is := "+IP.getHostAddress());

Wyjście dla mojego systemu = IP of my system is := 10.100.98.228

GetHostAddress () zwraca

Zwraca łańcuch adresu IP w prezentacji tekstowej.

Lub możesz też zrobić

InetAddress IP=InetAddress.getLocalHost();
System.out.println(IP.toString());

Output = IP of my system is := RanRag-PC/10.100.98.228

Przykład w Scali (przydatny w pliku sbt):

  import collection.JavaConverters._
  import java.net._

  def getIpAddress: String = {

    val enumeration = NetworkInterface.getNetworkInterfaces.asScala.toSeq

    val ipAddresses = enumeration.flatMap(p =>
      p.getInetAddresses.asScala.toSeq
    )

    val address = ipAddresses.find { address =>
      val host = address.getHostAddress
      host.contains(".") && !address.isLoopbackAddress
    }.getOrElse(InetAddress.getLocalHost)

    address.getHostAddress
  }

Kiedy szukasz swojego "lokalnego" adresu, powinieneś zauważyć, że każda maszyna ma nie tylko jeden interfejs sieciowy, a każdy interfejs może mieć swój własny adres lokalny. Co oznacza, że Twoja maszyna zawsze posiada kilka "lokalnych" adresów.

Różne "lokalne" adresy będą automatycznie wybierane do użycia podczas łączenia się z różnymi punktami końcowymi. Na przykład, gdy łączysz się z google.com, używasz" zewnętrznego " adresu lokalnego; ale gdy łączysz się z localhost, adres lokalny jest zawsze localhost, ponieważ localhost jest tylko pętlą zwrotną.

Poniżej pokazuję, jak dowiedzieć się, jaki jest Twój lokalny adres podczas komunikacji z google.com:

Socket socket = new Socket();
socket.connect(new InetSocketAddress("google.com", 80));
System.out.println(socket.getLocalAddress());

EDIT 1: zaktualizowany Kod, od poprzedniego linku, nie istnieje już

import java.io.*;
import java.net.*;

public class GetMyIP {
    public static void main(String[] args) {
        URL url = null;
        BufferedReader in = null;
        String ipAddress = "";
        try {
            url = new URL("http://bot.whatismyipaddress.com");
            in = new BufferedReader(new InputStreamReader(url.openStream()));
            ipAddress = in.readLine().trim();
            /* IF not connected to internet, then
             * the above code will return one empty
             * String, we can check it's length and
             * if length is not greater than zero, 
             * then we can go for LAN IP or Local IP
             * or PRIVATE IP
             */
            if (!(ipAddress.length() > 0)) {
                try {
                    InetAddress ip = InetAddress.getLocalHost();
                    System.out.println((ip.getHostAddress()).trim());
                    ipAddress = (ip.getHostAddress()).trim();
                } catch(Exception exp) {
                    ipAddress = "ERROR";
                }
            }
        } catch (Exception ex) {
            // This try will give the Private IP of the Host.
            try {
                InetAddress ip = InetAddress.getLocalHost();
                System.out.println((ip.getHostAddress()).trim());
                ipAddress = (ip.getHostAddress()).trim();
            } catch(Exception exp) {
                ipAddress = "ERROR";
            }
            //ex.printStackTrace();
        }
        System.out.println("IP Address: " + ipAddress);
    }
}

Aktualna wersja: to przestało działać

Mam nadzieję, że ten fragment pomoże Ci to osiągnąć:

// Method to get the IP Address of the Host.
private String getIP()
{
    // This try will give the Public IP Address of the Host.
    try
    {
        URL url = new URL("http://automation.whatismyip.com/n09230945.asp");
        BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
        String ipAddress = new String();
        ipAddress = (in.readLine()).trim();
        /* IF not connected to internet, then
         * the above code will return one empty
         * String, we can check it's length and
         * if length is not greater than zero, 
         * then we can go for LAN IP or Local IP
         * or PRIVATE IP
         */
        if (!(ipAddress.length() > 0))
        {
            try
            {
                InetAddress ip = InetAddress.getLocalHost();
                System.out.println((ip.getHostAddress()).trim());
                return ((ip.getHostAddress()).trim());
            }
            catch(Exception ex)
            {
                return "ERROR";
            }
        }
        System.out.println("IP Address is : " + ipAddress);

        return (ipAddress);
    }
    catch(Exception e)
    {
        // This try will give the Private IP of the Host.
        try
        {
            InetAddress ip = InetAddress.getLocalHost();
            System.out.println((ip.getHostAddress()).trim());
            return ((ip.getHostAddress()).trim());
        }
        catch(Exception ex)
        {
            return "ERROR";
        }
    }
}

Najpierw zaimportuj klasę

import java.net.InetAddress;

W klasie

  InetAddress iAddress = InetAddress.getLocalHost();
  String currentIp = iAddress.getHostAddress();
  System.out.println("Current IP address : " +currentIp); //gives only host address

private static InetAddress getLocalAddress(){
        try {
            Enumeration<NetworkInterface> b = NetworkInterface.getNetworkInterfaces();
            while( b.hasMoreElements()){
                for ( InterfaceAddress f : b.nextElement().getInterfaceAddresses())
                    if ( f.getAddress().isSiteLocalAddress())
                        return f.getAddress();
            }
        } catch (SocketException e) {
            e.printStackTrace();
        }
        return null;
    }

Możesz użyć java.net.InetAddress API. Spróbuj tego:

InetAddress.getLocalHost().getHostAddress();

To jest roboczy przykład zaakceptowanej odpowiedzi powyżej! Ta klasa NetIdentity będzie przechowywać zarówno wewnętrzny adres IP hosta, jak i lokalny loopback. Jeśli korzystasz z serwera opartego na DNS, Jak wspomniano powyżej, może być konieczne dodanie kilku dodatkowych kontroli lub przejście do trasy pliku konfiguracyjnego.

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Enumeration;

/**
 * Class that allows a device to identify itself on the INTRANET.
 * 
 * @author Decoded4620 2016
 */
public class NetIdentity {

    private String loopbackHost = "";
    private String host = "";

    private String loopbackIp = "";
    private String ip = "";
    public NetIdentity(){

        try{
            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();

            while(interfaces.hasMoreElements()){
                NetworkInterface i = interfaces.nextElement();
                if(i != null){
                    Enumeration<InetAddress> addresses = i.getInetAddresses();
                    System.out.println(i.getDisplayName());
                    while(addresses.hasMoreElements()){
                        InetAddress address = addresses.nextElement();
                        String hostAddr = address.getHostAddress();

                        // local loopback
                        if(hostAddr.indexOf("127.") == 0 ){
                            this.loopbackIp = address.getHostAddress();
                            this.loopbackHost = address.getHostName();
                        }

                        // internal ip addresses (behind this router)
                        if( hostAddr.indexOf("192.168") == 0 || 
                                hostAddr.indexOf("10.") == 0 || 
                                hostAddr.indexOf("172.16") == 0 ){
                            this.host = address.getHostName();
                            this.ip = address.getHostAddress();
                        }


                        System.out.println("\t\t-" + address.getHostName() + ":" + address.getHostAddress() + " - "+ address.getAddress());
                    }
                }
            }
        }
        catch(SocketException e){

        }
        try{
            InetAddress loopbackIpAddress = InetAddress.getLocalHost();
            this.loopbackIp = loopbackIpAddress.getHostName();
            System.out.println("LOCALHOST: " + loopbackIp);
        }
        catch(UnknownHostException e){
            System.err.println("ERR: " + e.toString());
        }
    }

    public String getLoopbackHost(){
        return loopbackHost;
    }

    public String getHost(){
        return host;
    }
    public String getIp(){
        return ip;
    }
    public String getLoopbackIp(){
        return loopbackIp;
    }
}

Kiedy uruchamiam ten kod, w rzeczywistości otrzymuję wydruk w ten sposób:

    Software Loopback Interface 1
        -127.0.0.1:127.0.0.1 - [B@19e1023e
        -0:0:0:0:0:0:0:1:0:0:0:0:0:0:0:1 - [B@7cef4e59
Broadcom 802.11ac Network Adapter
        -VIKING.yourisp.com:192.168.1.142 - [B@64b8f8f4
        -fe80:0:0:0:81fa:31d:21c9:85cd%wlan0:fe80:0:0:0:81fa:31d:21c9:85cd%wlan0 - [B@2db0f6b2
Microsoft Kernel Debug Network Adapter
Intel Edison USB RNDIS Device
Driver for user-mode network applications
Cisco Systems VPN Adapter for 64-bit Windows
VirtualBox Host-Only Ethernet Adapter
        -VIKING:192.168.56.1 - [B@3cd1f1c8
        -VIKING:fe80:0:0:0:d599:3cf0:5462:cb7%eth4 - [B@3a4afd8d
LogMeIn Hamachi Virtual Ethernet Adapter
        -VIKING:25.113.118.39 - [B@1996cd68
        -VIKING:2620:9b:0:0:0:0:1971:7627 - [B@3339ad8e
        -VIKING:fe80:0:0:0:51bf:994d:4656:8486%eth5 - [B@555590
Bluetooth Device (Personal Area Network)
        -fe80:0:0:0:4c56:8009:2bca:e16b%eth6:fe80:0:0:0:4c56:8009:2bca:e16b%eth6 - [B@3c679bde
Bluetooth Device (RFCOMM Protocol TDI)
Intel(R) Ethernet Connection (2) I218-V
        -fe80:0:0:0:4093:d169:536c:7c7c%eth7:fe80:0:0:0:4093:d169:536c:7c7c%eth7 - [B@16b4a017
Microsoft Wi-Fi Direct Virtual Adapter
        -fe80:0:0:0:103e:cdf0:c0ac:1751%wlan1:fe80:0:0:0:103e:cdf0:c0ac:1751%wlan1 - [B@8807e25
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0000
VirtualBox Host-Only Ethernet Adapter-WFP Native MAC Layer LightWeight Filter-0000
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0001
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0002
VirtualBox Host-Only Ethernet Adapter-VirtualBox NDIS Light-Weight Filter-0000
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0003
VirtualBox Host-Only Ethernet Adapter-QoS Packet Scheduler-0000
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0004
VirtualBox Host-Only Ethernet Adapter-WFP 802.3 MAC Layer LightWeight Filter-0000
VirtualBox Host-Only Ethernet Adapter-HHD Software NDIS 6.0 Filter Driver-0005
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0000
Intel(R) Ethernet Connection (2) I218-V-WFP Native MAC Layer LightWeight Filter-0000
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0001
Intel(R) Ethernet Connection (2) I218-V-Shrew Soft Lightweight Filter-0000
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0002
Intel(R) Ethernet Connection (2) I218-V-VirtualBox NDIS Light-Weight Filter-0000
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0003
Intel(R) Ethernet Connection (2) I218-V-QoS Packet Scheduler-0000
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0004
Intel(R) Ethernet Connection (2) I218-V-WFP 802.3 MAC Layer LightWeight Filter-0000
Intel(R) Ethernet Connection (2) I218-V-HHD Software NDIS 6.0 Filter Driver-0005
Broadcom 802.11ac Network Adapter-WFP Native MAC Layer LightWeight Filter-0000
Broadcom 802.11ac Network Adapter-Virtual WiFi Filter Driver-0000
Broadcom 802.11ac Network Adapter-Native WiFi Filter Driver-0000
Broadcom 802.11ac Network Adapter-HHD Software NDIS 6.0 Filter Driver-0003
Broadcom 802.11ac Network Adapter-Shrew Soft Lightweight Filter-0000
Broadcom 802.11ac Network Adapter-HHD Software NDIS 6.0 Filter Driver-0004
Broadcom 802.11ac Network Adapter-VirtualBox NDIS Light-Weight Filter-0000
Broadcom 802.11ac Network Adapter-HHD Software NDIS 6.0 Filter Driver-0005
Broadcom 802.11ac Network Adapter-QoS Packet Scheduler-0000
Broadcom 802.11ac Network Adapter-HHD Software NDIS 6.0 Filter Driver-0006
Broadcom 802.11ac Network Adapter-WFP 802.3 MAC Layer LightWeight Filter-0000
Broadcom 802.11ac Network Adapter-HHD Software NDIS 6.0 Filter Driver-0007
Microsoft Wi-Fi Direct Virtual Adapter-WFP Native MAC Layer LightWeight Filter-0000
Microsoft Wi-Fi Direct Virtual Adapter-Native WiFi Filter Driver-0000
Microsoft Wi-Fi Direct Virtual Adapter-HHD Software NDIS 6.0 Filter Driver-0002
Microsoft Wi-Fi Direct Virtual Adapter-Shrew Soft Lightweight Filter-0000
Microsoft Wi-Fi Direct Virtual Adapter-HHD Software NDIS 6.0 Filter Driver-0003
Microsoft Wi-Fi Direct Virtual Adapter-VirtualBox NDIS Light-Weight Filter-0000
Microsoft Wi-Fi Direct Virtual Adapter-HHD Software NDIS 6.0 Filter Driver-0004
Microsoft Wi-Fi Direct Virtual Adapter-QoS Packet Scheduler-0000
Microsoft Wi-Fi Direct Virtual Adapter-HHD Software NDIS 6.0 Filter Driver-0005
Microsoft Wi-Fi Direct Virtual Adapter-WFP 802.3 MAC Layer LightWeight Filter-0000
Microsoft Wi-Fi Direct Virtual Adapter-HHD Software NDIS 6.0 Filter Driver-0006

Do mojego użytku konfiguruję serwer Upnp, pomogło to zrozumieć "wzór" , którego szukałem. Niektóre z zwracane obiekty to Karty sieciowe Ethernet, karty sieciowe, karty sieci wirtualnych, sterowniki i Karty Klienta VPN. Nie wszystko ma adres. Więc będziesz chciał pominąć obiekty interfejsu, które tego nie robią.

Możesz również dodać to do pętli dla bieżącego NetworkInterface i

while(interfaces.hasMoreElements()){
    Enumeration<InetAddress> addresses = i.getInetAddresses();
    System.out.println(i.getDisplayName());
    System.out.println("\t- name:" + i.getName());
    System.out.println("\t- idx:" + i.getIndex());
    System.out.println("\t- max trans unit (MTU):" + i.getMTU());
    System.out.println("\t- is loopback:" + i.isLoopback());
    System.out.println("\t- is PPP:" + i.isPointToPoint());
    System.out.println("\t- isUp:" + i.isUp());
    System.out.println("\t- isVirtual:" + i.isVirtual());
    System.out.println("\t- supportsMulticast:" + i.supportsMulticast());
}

I zobaczysz informacje w swoim wyjściu mniej więcej tak:

Software Loopback Interface 1
    - name:lo
    - idx:1
    - max trans unit (MTU):-1
    - is loopback:true
    - is PPP:false
    - isUp:true
    - isVirtual:false
    - supportsMulticast:true
        -ADRESS: [127.0.0.1(VIKING-192.168.56.1)]127.0.0.1:127.0.0.1 - [B@19e1023e
        -ADRESS: [0:0:0:0:0:0:0:1(VIKING-192.168.56.1)]0:0:0:0:0:0:0:1:0:0:0:0:0:0:0:1 - [B@7cef4e59
Broadcom 802.11ac Network Adapter
    - name:wlan0
    - idx:2
    - max trans unit (MTU):1500
    - is loopback:false
    - is PPP:false
    - isUp:true
    - isVirtual:false
    - supportsMulticast:true
        -ADRESS: [VIKING.monkeybrains.net(VIKING-192.168.56.1)]VIKING.monkeybrains.net:192.168.1.142 - [B@64b8f8f4
        -ADRESS: [fe80:0:0:0:81fa:31d:21c9:85cd%wlan0(VIKING-192.168.56.1)]fe80:0:0:0:81fa:31d:21c9:85cd%wlan0:fe80:0:0:0:81fa:31d:21c9:85cd%wlan0 - [B@2db0f6b2
Microsoft Kernel Debug Network Adapter
    - name:eth0
    - idx:3
    - max trans unit (MTU):-1
    - is loopback:false
    - is PPP:false
    - isUp:false
    - isVirtual:false
    - supportsMulticast:true

Użyj InetAddress.getLocalHost () to get the local address

import java.net.InetAddress;

try {
  InetAddress addr = InetAddress.getLocalHost();            
  System.out.println(addr.getHostAddress());
} catch (UnknownHostException e) {
}

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

public class IpAddress {

NetworkInterface ifcfg;
Enumeration<InetAddress> addresses;
String address;

public String getIpAddress(String host) {
    try {
        ifcfg = NetworkInterface.getByName(host);
        addresses = ifcfg.getInetAddresses();
        while (addresses.hasMoreElements()) {
            address = addresses.nextElement().toString();
            address = address.replace("/", "");
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    return ifcfg.toString();
}
}

Dość uproszczone podejście, które wydaje się działać...

String getPublicIPv4() throws UnknownHostException, SocketException{
    Enumeration<NetworkInterface> e = NetworkInterface.getNetworkInterfaces();
    String ipToReturn = null;
    while(e.hasMoreElements())
    {
        NetworkInterface n = (NetworkInterface) e.nextElement();
        Enumeration<InetAddress> ee = n.getInetAddresses();
        while (ee.hasMoreElements())
        {
            InetAddress i = (InetAddress) ee.nextElement();
            String currentAddress = i.getHostAddress();
            logger.trace("IP address "+currentAddress+ " found");
            if(!i.isSiteLocalAddress()&&!i.isLoopbackAddress() && validate(currentAddress)){
                ipToReturn = currentAddress;    
            }else{
                System.out.println("Address not validated as public IPv4");
            }

        }
    }

    return ipToReturn;
}

private static final Pattern IPv4RegexPattern = Pattern.compile(
        "^(([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.){3}([01]?\\d\\d?|2[0-4]\\d|25[0-5])$");

public static boolean validate(final String ip) {
    return IPv4RegexPattern.matcher(ip).matches();
}

Zwykle, gdy próbuję znaleźć mój publiczny adres IP, jak cmyip.com lub www.iplocation.net , używam w ten sposób:

public static String myPublicIp() {

    /*nslookup myip.opendns.com resolver1.opendns.com*/
    String ipAdressDns  = "";
    try {
        String command = "nslookup myip.opendns.com resolver1.opendns.com";
        Process proc = Runtime.getRuntime().exec(command);

        BufferedReader stdInput = new BufferedReader(new InputStreamReader(proc.getInputStream()));

        String s;
        while ((s = stdInput.readLine()) != null) {
            ipAdressDns  += s + "\n";
        }
    } catch (IOException e) {
        e.printStackTrace();
    }

    return ipAdressDns ;
}

public static String getIpAddress() {

    String ipAddress = null;

    try {
        Enumeration<NetworkInterface> networkInterfaces = NetworkInterface.getNetworkInterfaces();

        while (networkInterfaces.hasMoreElements()) {

            NetworkInterface networkInterface = networkInterfaces.nextElement();

            byte[] hardwareAddress = networkInterface.getHardwareAddress();
            if (null == hardwareAddress || 0 == hardwareAddress.length || (0 == hardwareAddress[0] && 0 == hardwareAddress[1] && 0 == hardwareAddress[2])) continue;

            Enumeration<InetAddress> inetAddresses = networkInterface.getInetAddresses();

            if (inetAddresses.hasMoreElements()) ipAddress = inetAddresses.nextElement().toString();

            break;
        }
    } catch (SocketException e) {
        e.printStackTrace();
    }

    return ipAddress;
}