NetUtil

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


public class NetUtil {


    public static String getDefaultHostName() throws SocketException {
        Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces();
        while (en.hasMoreElements()) {
            NetworkInterface nif = en.nextElement();
            Enumeration<InetAddress> addresses = nif.getInetAddresses();
            while (addresses.hasMoreElements()) {
                InetAddress address = addresses.nextElement();
                if (!address.isLinkLocalAddress() && !address.isLoopbackAddress()) {
                    return address.getHostName();
                }
            }
        }
        return "localhost";
    }
    
    public static String getDefaultHostIp() throws SocketException {
        Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces();
        while (en.hasMoreElements()) {
            NetworkInterface nif = en.nextElement();
            Enumeration<InetAddress> addresses = nif.getInetAddresses();
            while (addresses.hasMoreElements()) {
                InetAddress address = addresses.nextElement();
                if (!address.isLinkLocalAddress() && !address.isLoopbackAddress()) {
                    return address.getHostAddress();
                }
            }
        }
        return "127.0.0.1";
    }
    
    public static String getEncodedServer(String server) throws UnknownHostException {
        StringTokenizer tokenizer = new StringTokenizer(server, ":");
        String hostName = tokenizer.nextToken();
        String port = tokenizer.nextToken();
        InetAddress inetAddress = InetAddress.getByName(hostName);
        byte[] rawIp = inetAddress.getAddress();
        StringBuilder builder = new StringBuilder(hostName);
        builder.append(":");
        builder.append(BASE64Encoder.get().encode(rawIp));
        builder.append(":");
        builder.append(port);
        return builder.toString();
    }

}

/*
 * BASE64Encoder.java
 *
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

import java.io.OutputStream;
import java.io.IOException;


/**
 * This class implements a BASE64 Character encoder as specified in RFC1521.
 * This RFC is part of the MIME specification as published by the Internet 
 * Engineering Task Force (IETF). Unlike some other encoding schemes there 
 * is nothing in this encoding that indicates
 * where a buffer starts or ends.
 *
 */


public class BASE64Encoder extends CharacterEncoder {
    
    private static final BASE64Encoder SINGLETON = new BASE64Encoder();
    
    public static BASE64Encoder get() {
        return SINGLETON;
    }

    /** this class encodes three bytes per atom. */
    protected int bytesPerAtom() {
return (3);
    }


    /** 
     * this class encodes 57 bytes per line. This results in a maximum
     * of 57/3 * 4 or 76 characters per output line. Not counting the
     * line termination.
     */
    protected int bytesPerLine() {
return (57);
    }


    /** This array maps the characters to their 6 bit values */
    private final static char pem_array[] = {
//       0   1   2   3   4   5   6   7
'A','B','C','D','E','F','G','H', // 0
'I','J','K','L','M','N','O','P', // 1
'Q','R','S','T','U','V','W','X', // 2
'Y','Z','a','b','c','d','e','f', // 3
'g','h','i','j','k','l','m','n', // 4
'o','p','q','r','s','t','u','v', // 5
'w','x','y','z','0','1','2','3', // 6
'4','5','6','7','8','9','+','/'  // 7
};


    /** 
     * encodeAtom - Take three bytes of input and encode it as 4
     * printable characters. Note that if the length in len is less
     * than three is encodes either one or two '=' signs to indicate
     * padding characters.
     */
    protected void encodeAtom(OutputStream outStream, byte data[], int offset, int len) 
throws IOException {
byte a, b, c;


if (len == 1) {
   a = data[offset];
   b = 0;
   c = 0;
   outStream.write(pem_array[(a >>> 2) & 0x3F]);
   outStream.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);
   outStream.write('=');
   outStream.write('=');
} else if (len == 2) {
   a = data[offset];
   b = data[offset+1];
   c = 0;
   outStream.write(pem_array[(a >>> 2) & 0x3F]);
   outStream.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);
   outStream.write(pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)]);
   outStream.write('=');
} else {
   a = data[offset];
   b = data[offset+1];
   c = data[offset+2];
   outStream.write(pem_array[(a >>> 2) & 0x3F]);
   outStream.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);
   outStream.write(pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)]);
   outStream.write(pem_array[c & 0x3F]);
}
    }
    
    public static void main(String[] args) throws Exception {
        BASE64Encoder encoder = get();
        System.out.println(encoder.encode("china".getBytes()));
        System.out.println(encoder.encode("usa".getBytes()));
        System.out.println(encoder.encode("russia".getBytes()));
        System.out.println(encoder.encode("japan".getBytes()));
    }
}