<code java>
package nslookup;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.util.HashMap;
import java.util.Map;

public class ServerThread extends Thread {

        Map<String,InetAddress> cache = null;
        Socket s = null; 

        public ServerThread(Map<String,InetAddress> c, Socket ts) {
                cache = c;
                s = ts; 
        }

        public void run() {
                try {
                        System.out.println("ServerThread started");
                        ObjectInputStream ois = new ObjectInputStream(s.getInputStream());
                        Object o = ois.readObject();
                        if(o instanceof NameQuery) {
                                // trattamento della richiesta
                                NameQuery nq = (NameQuery) o;
                                String hostName = nq.getHostname();
                                System.out.println("Looking up "+hostName);
                                if(cache.containsKey(hostName) && nq.getCached()) {
                                        System.out.println(hostName+" gia' in cache con indirizzo "+cache.get(host
Name));
                                } else { // host non in cache o cached false
                                        if(cache.containsKey(hostName)) { // se c'era, cancellalo prima di reineri
rlo
                                                InetAddress ia = cache.get(hostName);
                                                cache.remove(hostName);
                                                System.out.println("Cancellata entry cache <"+hostName+","+ia+">")
;
                                        }
                                        InetAddress ia = InetAddress.getByName(hostName);
                                        cache.put(hostName, ia);
                                        System.out.println("Aggiunto in cache: <"+hostName+","+ia+">");
                                }
                                // adesso invia la risposta
                                ObjectOutputStream oos = new ObjectOutputStream(s.getOutputStream());
                                QueryAnswer qa = new QueryAnswer(hostName,cache.get(hostName));
                                oos.writeObject(qa);
                                return;
                        } else {
                                // tipo non previsto, restituisce un messaggio di errore
                                ObjectOutputStream oos = new ObjectOutputStream(s.getOutputStream());
                                System.out.println("Tipo imprevisto per l'oggetto letto");
                                QueryAnswer qa = new QueryAnswer();
                                oos.writeObject(qa);
                                return;
                        }
                } catch (IOException e) {
                        e.printStackTrace();
                } catch (ClassNotFoundException e) {
                        System.out.println("Non trovo la class per l'oggetto letto");
                        return;
                }
        }

}
</code>