package common;

import java.net.InetAddress;

import java.net.UnknownHostException;

/**

* Build key value used to identify this view-controller/client to the

* model/server as hex representation of last 3 bytes (least significant

* bytes) of IP address giving a six character key. This is a static class

* and cannot be instantiated. Instead use IpDtaQKey.getDqKey().

* @author Bill Blalock

*

*/

public class IpDtaQKey {

private static IpDtaQKey INSTANCE;

private static String dqKey;

/**

* Private constructor. Constructor only invoked by DtaQKey.getDqKey().

* <p>

* Build key value used to identify this view-controller/client to the

* model/server as hex representation of last 3 bytes (least significant

* bytes) of IP address giving a six character key.

* @return Six character key used to identify this view-controller/client

* to the model/server.

*/

private IpDtaQKey() {

try {

InetAddress addr = InetAddress.getLocalHost();

// Get IP Address

byte[] ipAddr = addr.getAddress();

// Convert to hex

StringBuffer sb = new StringBuffer();

for (int i = 0; i < ipAddr.length; i++) {

if( ipAddr[i]>= 0 & ipAddr[i] < 16 )

sb.append("0");

sb.append(Integer.toHexString(((int) ipAddr[i]) & 0xFF));

}

String hexIpAddr = sb.toString();

// return least 3 significant bytes, 6 character hex

dqKey = hexIpAddr.toUpperCase().substring(2);

} catch (UnknownHostException e) {

dqKey = "FFFFFF";

}

}

/**

* Get key used to identify this view-controller/client to the model/server.

* @return Key used to identify this view-controller/client to the model/server.

* "FFFFFF" indicate that class was unable to build a key from the IP address.

*/

public static String getDqKey() {

if( INSTANCE == null )

INSTANCE = new IpDtaQKey();

return dqKey;

}

}