Java Host Name Get getHostGateway()

Description

get Host Gateway

License

Apache License

Declaration

public static InetAddress getHostGateway() 

Method Source Code

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

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

public class Main {
    public static InetAddress getHostGateway() {
        @SuppressWarnings("unused")
        String _gateway = null, _ip = null;
        if (System.getProperty("os.name").startsWith("Windows")) {
            return parseWindows();
        }/*from  w  w w .  jav  a2s .c o  m*/

        try {
            BufferedReader reader = new BufferedReader(new FileReader("/proc/net/route"));

            String line;
            while ((line = reader.readLine()) != null) {
                line = line.trim();
                String[] tokens = line.split(" ");
                if (tokens.length > 1 && tokens[1].equals("00000000")) {
                    String gateway = tokens[2]; //0102A8C0
                    if (gateway.length() == 8) {
                        String[] s4 = new String[4];
                        s4[3] = String.valueOf(Integer.parseInt(gateway.substring(0, 2), 16));
                        s4[2] = String.valueOf(Integer.parseInt(gateway.substring(2, 4), 16));
                        s4[1] = String.valueOf(Integer.parseInt(gateway.substring(4, 6), 16));
                        s4[0] = String.valueOf(Integer.parseInt(gateway.substring(6, 8), 16));
                        _gateway = s4[0] + "." + s4[1] + "." + s4[2] + "." + s4[3];
                    }

                    String iface = tokens[0];
                    NetworkInterface nif = NetworkInterface.getByName(iface);
                    Enumeration<InetAddress> addrs = nif.getInetAddresses();
                    while (addrs.hasMoreElements()) {
                        Object obj = addrs.nextElement();
                        if (obj instanceof Inet4Address) {
                            _ip = obj.toString();
                            if (_ip.startsWith("/"))
                                _ip = _ip.substring(1);
                        }
                    }
                }
            }
            reader.close();
            return InetAddress.getByName(_ip);
        } catch (Exception ex) {
        }

        return null;
    }

    private static InetAddress parseWindows() {
        try {
            @SuppressWarnings("unused")
            String _gateway = null, _ip = null;
            Process pro = Runtime.getRuntime().exec("route print");
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(pro.getInputStream()));

            String line;
            while ((line = bufferedReader.readLine()) != null) {
                line = line.trim();
                String[] tokens = line.split(" ");
                List<String> args = new ArrayList<>();
                for (String l : tokens) {
                    if (!(l.equals("") || l.equalsIgnoreCase(" ") || l.startsWith(" "))) {
                        args.add(l);
                    }
                }

                tokens = args.toArray(new String[args.size()]);
                if (tokens.length == 5 && tokens[0].equals("0.0.0.0")) {
                    _gateway = tokens[2];
                    _ip = tokens[3];
                    return InetAddress.getByName(tokens[2]);
                }
            }
        } catch (IOException ex) {
        }

        return null;
    }
}

Related

1. getHost()
2. getHost(String host)
3. getHost(String link)
4. getHost(String s)
5. getHostCore(final String quadGraph)
6. getHostInformation()
7. getHostMac(String host)
8. getHostName()
9. getHostName()