Java Local Address Get getLocalAddressFromNetworkInterfacesListeningOnPort(int pPort)

Description

get Local Address From Network Interfaces Listening On Port

License

Apache License

Declaration

private static InetAddress getLocalAddressFromNetworkInterfacesListeningOnPort(int pPort) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.io.IOException;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.*;
import java.util.*;

public class Main {
    private static Method isUp;

    private static InetAddress getLocalAddressFromNetworkInterfacesListeningOnPort(int pPort) {
        try {/*from   ww w. ja  v  a 2 s  . c o m*/
            Enumeration<NetworkInterface> networkInterfaces;
            networkInterfaces = NetworkInterface.getNetworkInterfaces();
            while (networkInterfaces.hasMoreElements()) {
                NetworkInterface nif = networkInterfaces.nextElement();
                for (Enumeration<InetAddress> addrEnum = nif.getInetAddresses(); addrEnum.hasMoreElements();) {
                    InetAddress interfaceAddress = addrEnum.nextElement();
                    if (!interfaceAddress.isLoopbackAddress() && checkMethod(nif, isUp)
                            && isPortOpen(interfaceAddress, pPort)) {
                        return interfaceAddress;
                    }
                }
            }
        } catch (SocketException e) {
            return null;
        }
        return null;
    }

    private static Boolean checkMethod(NetworkInterface iface, Method toCheck) {
        if (toCheck != null) {
            try {
                return (Boolean) toCheck.invoke(iface, (Object[]) null);
            } catch (IllegalAccessException e) {
                return false;
            } catch (InvocationTargetException e) {
                return false;
            }
        }
        // Cannot check, hence we assume that is true
        return true;
    }

    private static boolean isPortOpen(InetAddress pAddress, int pPort) {
        Socket socket = null;
        try {
            socket = new Socket();
            socket.setReuseAddress(true);
            SocketAddress sa = new InetSocketAddress(pAddress, pPort);
            socket.connect(sa, 200);
            return socket.isConnected();
        } catch (IOException e) {
            return false;
        } finally {
            if (socket != null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    // Best effort. Hate that close throws an IOException, btw. Never saw a real use case for that.
                }
            }
        }
    }
}

Related

1. getLocalAddressAsString()
2. getLocalAddresses()
3. getLocalAddresses()
4. getLocalAddresses()
5. getLocalAddresses()
6. getLocalAddressStrings()
7. getLocalAddressWithMulticast()
8. getLocalAddrs()
9. getLocalInet4Address()