import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.Charset;
import java.io.Reader;
 
public class ServeurTCP
{
  private final static char[] hexArray = "0123456789ABCDEF".toCharArray();
  public static String bytesToHex(byte[] bytes, int numCharsRead) {
    char[] hexChars = new char[numCharsRead * 3];
    for ( int j = 0; j < numCharsRead; j++ ) {
      int v = bytes[j] & 0xFF;
      hexChars[j * 3] = hexArray[v >>> 4];
      hexChars[j * 3 + 1] = hexArray[v & 0x0F];
      hexChars[j * 3 + 2] = ' ';
    }
    return new String(hexChars);
  }

  public static Integer tryParse(String text) {
    try {
      return Integer.parseInt(text);
    } catch (NumberFormatException e) {
      return null;
    }
  }
  
  public static void main (String[] args)
  {
    if (args.length != 1)
    {
      System.out.println("utilisation : ServeurTCP port");
      return;
    }
    Integer port = tryParse(args[0]);
    if (port == null)
    {
      System.out.println("Numéro de port incorrect");
      return;
    }
    try (ServerSocket server = new ServerSocket (port);)
    {
      System.out.println ("en attente de connexion");
      while (true)
      {
        // Attente du client
        Socket client = server.accept ();
        client.setTcpNoDelay(true);
        try (
            InputStream stream = client.getInputStream ())
        {
          System.out.println ("connexion étalie avec " + client.getInetAddress ());
          
          byte[] charArray = new byte[8 * 1024];
 
          while (true)
          {
            System.out.println ("Lecture...");
            // Lecture du message du client
            int numCharsRead = stream.read(charArray, 0, charArray.length);
            if (numCharsRead == -1)
            {
              break;
            }
            System.out.println (bytesToHex(charArray, numCharsRead));
           }
        }
        catch (java.net.SocketException e)
        {
            System.out.println ("Fin rapide avec " + client.getInetAddress ());
        }
      }
    }
    catch (Exception e)
    {
      e.printStackTrace();
      return;
    }
  }
}