Java Network Interface Get enumerateInterfaces()

Description

We must use -Djava.net.preferIPv4Stack=true to get expected results for broadcast address and prefix length.

License

Open Source License

Exception

Parameter	Description
SocketException	an exception

Declaration

public static void enumerateInterfaces() throws SocketException 

Method Source Code

//package com.java2s;
// it under the terms of the GNU General Public License as published by

import java.net.InterfaceAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.Enumeration;

public class Main {
    /**********************************************************************************************
     * We must use -Djava.net.preferIPv4Stack=true to get expected results
     * for broadcast address and prefix length.
     *//from w  ww.ja v  a2 s .co m
     * @throws SocketException
     */

    public static void enumerateInterfaces() throws SocketException {
        final Enumeration<NetworkInterface> interfaces;

        // Returns all the interfaces on this machine.
        // Returns null if no network interfaces could be found on this machine.
        for (interfaces = NetworkInterface.getNetworkInterfaces(); interfaces.hasMoreElements();) {
            final NetworkInterface networkInterface;

            networkInterface = interfaces.nextElement();

            if ((networkInterface.isUp()) && (!networkInterface.isVirtual())) {
                // Begin with no indent
                reportInterface(networkInterface, "");
            }
        }
    }

    /***********************************************************************************************
     * Show all details of a Network Interface.
     * May be called recursively.
     *
     * @param networkinterface
     * @param indent
     *
     * @throws SocketException
     */

    private static void reportInterface(final NetworkInterface networkinterface, String indent)
            throws SocketException {
        final byte[] arrayMAC;
        final Enumeration<NetworkInterface> interfaces;

        // Get a List of all or a subset of the InterfaceAddresses of this network interface
        // Get an Enumeration with all the subinterfaces (also known as virtual interfaces) attached to this network interface
        if ((networkinterface.getInterfaceAddresses().isEmpty())
                && (!networkinterface.getSubInterfaces().hasMoreElements())) {
            return; // has no addresses or child interfaces
        }

        System.out.print(indent);
        System.out.print("/");
        System.out.print(networkinterface.getDisplayName());
        System.out.print("/");

        // Returns whether a network interface is a loopback interface
        if (networkinterface.isLoopback()) {
            System.out.print(" [loopback]");
        }

        // Returns whether a network interface is a point to point interface
        if (networkinterface.isPointToPoint()) {
            System.out.print(" [ptp]");
        }

        // Returns the hardware address (usually MAC) of the interface if it has one
        // and if it can be accessed given the current privileges
        arrayMAC = networkinterface.getHardwareAddress();

        if ((arrayMAC != null) && (arrayMAC.length > 0)) {
            System.out.print(", hardware=");

            for (final byte byteMAC : arrayMAC) {
                System.out.print(':');
                System.out.print(Integer.toHexString(byteMAC & 0xff));
            }
        }

        System.out.println();
        indent = indent + "  ";

        // Now the InterfaceAddress information
        for (final InterfaceAddress interfaceAddress : networkinterface.getInterfaceAddresses()) {
            System.out.print(indent);
            System.out.print(interfaceAddress.getAddress());

            // Returns an InetAddress for this address
            if (interfaceAddress.getAddress().isLoopbackAddress()) {
                System.out.print(" [loopback]");
            }

            System.out.print(", broadcast=");
            System.out.print(interfaceAddress.getBroadcast());

            System.out.print(", prefixLength=");
            System.out.print(interfaceAddress.getNetworkPrefixLength());

            //System.out.print(", searchedBroadcast=");
            //System.out.print(BroadcastAddress.instance().getBroadcastAddress(addr.getAddress()));

            try {
                final String strHostname;

                strHostname = interfaceAddress.getAddress().getCanonicalHostName();

                if (strHostname != null) {
                    System.out.print(", host=");
                    System.out.print(strHostname);
                }
            }

            catch (Exception exception) {
                // Just ignore any Exceptions
            }

            System.out.println();
        }

        // Now recurse down through the subinterfaces

        for (interfaces = networkinterface.getSubInterfaces(); interfaces.hasMoreElements();) {
            final NetworkInterface childInterface;

            childInterface = interfaces.nextElement();

            if (childInterface.isUp()) {
                reportInterface(childInterface, indent);
            }
        }
    }
}

Related

1. getAllAvailableInterfaces()
2. getAllAvailableInterfaces()
3. getAllAvailableInterfaces()
4. getAllInterfaces()