siuap

import java.io.*;
import java.net.*;
import java.io.IOException;

class Odbior extends Thread {
    Socket sock;
    BufferedReader sockReader;
    PrintWriter sockWriter;

    public Odbior(Socket sock) throws IOException {
        this.sock = sock;
        this.sockReader = new BufferedReader(new InputStreamReader(sock.getInputStream()));
    }

    public void run() {
        try {
            String str;
            while(true) {
                if (sockReader.ready()) {
                    str = this.sockReader.readLine();
                    if (str.equalsIgnoreCase("koniec")) {
                        sock.shutdownOutput();
                        break;
                    }
                    System.out.println(str);
                }
                else if (sock.isInputShutdown()) {
                    break;
                }
            }
        }
        catch  (Exception e) {
            e.printStackTrace();;
        }
    }
}

class Nadaj extends Thread
{
    Socket sock;
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    PrintWriter sockWriter;
    String nick;

    public Nadaj(Socket sock, String nick) throws IOException
    {
        this.sock = sock;
        this.nick = nick;
        this.sockWriter = new PrintWriter(sock.getOutputStream());
    }

    public void run() {
        try {
            PrintWriter out = this.sockWriter;
            String str;
            while (true) {
                if(in.ready()) {
                    str = in.readLine();
                    if (str.equalsIgnoreCase("koniec")) {
                        out.println(str);
                        sock.shutdownInput();
                        in.close();
                        break;
                    }
                    out.println(this.nick + " " + str);
                } else if (sock.isOutputShutdown()) break;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

public class Klient
{
    public static final int PORT=50007;
    public static final String HOST = "155.158.131.155";

    public static void main(String[] args) throws IOException
    {
        //nawiazanie polaczenia z serwerem
        Socket sock;
        sock=new Socket(HOST, PORT);
        System.out.println("Nawiazalem polaczenie: "+sock);

        //tworzenie watka odbierajacego
        Odbior odbior = new Odbior(sock);
        Nadaj nadaj = new Nadaj(sock, "Gaspar");
        odbior.start();
        nadaj.start();
        while(true) {
            if (!nadaj.isAlive() | !odbior.isAlive()) {
                break;
            }
        }

        System.out.println("Koniec poloczenia");

        //zamykanie polaczenia
        sock.close();
    }
}


*********************************************************************************************************************

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

public class SerwerMulti {
    public static final int PORT=5007;
    private static Set<String>names = new HashSet<>();
    private  static Set<PrintWriter>senders = new HashSet<>();

    public static void main(String args[]) throws IOException {
        ServerSocket server = new ServerSocket(PORT);
        Socket client;

        System.out.println("Waiting for connection to: " + server);
        while(true) {
            client = server.accept();
            new ClientHandler(client).start();
        }
    }

    private static class ClientHandler extends Thread {
        private String name;
        private Socket client;

        private BufferedReader clientReceiver;
        private PrintWriter clientSender;
        public ClientHandler(Socket client) {
            this.client = client;
        }

        public void run() {
            try {
                this.clientReceiver = new BufferedReader(new InputStreamReader(this.client.getInputStream()));
                this.clientSender = new PrintWriter(this.client.getOutputStream());

                this.clientSender.println("Your name?");
                this.clientSender.flush();

                while(true) {
                    if (this.clientReceiver.ready()) {
                        this.name = this.clientReceiver.readLine();
                        synchronized (names) {
                            if (!this.name.trim().isEmpty() && !names.contains(name)) {
                                names.add(this.name);

                                this.clientSender.println("Welcome "+this.name+"!");
                                this.clientSender.flush();
                                break;
                            } else {
                                this.clientSender.println("Name: "+this.name+" is already in use!\n"+"Your name?");
                                this.clientSender.flush();
                            }
                        }
                    }
                }
                for (PrintWriter sender: senders) {
                    sender.println(this.name + "has joined");
                    sender.flush();
                }
                senders.add(this.clientSender);
                String message = "";
                boolean exit = false;

                while(!exit) {
                    if (this.clientReceiver.ready()) {
                        message = this.clientReceiver.readLine();

                        if(!message.equalsIgnoreCase("end")) {
                            message = "<" + this.name + ">:" + message;
                        } else {
                            message = this.name + "has left";
                            exit = true;
                        }
                        for (PrintWriter sender: senders) {
                            if(sender != this.clientSender) {
                                sender.println(message);
                                sender.flush();
                            }
                        }
                    }
                }
                senders.remove(this.clientSender);
                names.remove(this.name);

                this.clientReceiver.close();
                this.clientSender.close();
                this.client.close();
            }

            catch (IOException e) {
                System.out.println(e);
            }
        }
    }
}