Java socket + HTML5 websocket

// Server.java <=== Server
package webSocket;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.StringTokenizer;

public class Server {

    ArrayList<NewClient> clientArray = new ArrayList<NewClient>();

    int PORT = 4447;

    private ServerSocket serverSocket;
    private Socket clientSocket;

    public Server() throws IOException, Exception {
        serverSocket = new ServerSocket(PORT);
        System.out.println("Server Connected...");

        while (true) {
            clientSocket = serverSocket.accept(); //accept new client
            NewClient newClient = new NewClient(this, clientSocket);
            newClient.start();

            // clientArray will be added after receiving message from client
            clientArray.add(newClient);
        }
    }

//    public void broadcast(String msgFromClient) throws IOException {
//        // send message to all connected usersArray
//        synchronized (clientArray) {
//            for (NewClient newClient : clientArray) {
//                newClient.sendToMe(msgFromClient.getBytes());
//            }
//        }
//    }

    public static void main(String[] args) throws IOException, InterruptedException, NoSuchAlgorithmException, Exception {
        new Server();
    }
}


//NewClient.java  <=== Server
package webSocket;

import java.io.*;
import java.net.*;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.StringTokenizer;
import sun.misc.BASE64Encoder;

public class NewClient extends Thread {

    Socket clientSocket;
    Server server;

    String loginName = "";
    String loginIP = "";

    BufferedReader in;
    PrintWriter out;

    public static final int MASK_SIZE = 4;
    public static final int SINGLE_FRAME_UNMASKED = 0x81;

    public NewClient(Server server, Socket client) throws IOException {

        this.clientSocket = client;
        this.server = server;

        in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        out = new PrintWriter(clientSocket.getOutputStream());

        if (handshake()) {

            try {
                // LOGIN
                String loginInfo = receiveMessage();  //first data from client
                // userName@/127.0.0.1 => (userName, userIP)
                StringTokenizer tok = new StringTokenizer(loginInfo, "@");

                loginName = tok.nextToken();

                String tempLogin = "Welcome " + loginName;
                sendToMe(tempLogin.getBytes());

                // new user
                if (server.clientArray.size() > 0) {
                    String temp = "";
                    for (NewClient newClient : server.clientArray) {
                        temp += (newClient.loginName) + "@";
                    }
                    // send other's login info to me
                    String tempUserlist = "USERLIST@" + server.clientArray.size() + "@" + temp;
                    sendToMe(tempUserlist.getBytes());
                }

                // old user
                for (NewClient newClient : server.clientArray) {
                    // send my login info to other
                    String tempAdd = "ADD@" + loginName;
                    newClient.sendToMe(tempAdd.getBytes());
                }
            } // try
            catch (Exception e) {
                System.out.println(e.getMessage());
            }
        }
    }

    public void run() {
        String msgFromClient = null;
        // msgFromClient = username@ALL@hello world
        while (true) {
            try {
                msgFromClient = receiveMessage();

                if (msgFromClient.equals("CLOSE")) {

                    for (NewClient newClient : server.clientArray) {
                        String tempDelete = "DELETE@" + loginName;
                        newClient.sendToMe(tempDelete.getBytes());
                    }

                    server.clientArray.remove(this);

                    in.close();
                    out.close();
                    clientSocket.close();
                    return;  // or break;

                    //break;
                } else {

                    // msgFromClient = username@ALL@hello world
                    StringTokenizer token = new StringTokenizer(msgFromClient, "@");

                    String sender = token.nextToken();
                    String receiver = token.nextToken();
                    String content = token.nextToken();

                    for (NewClient newClient : server.clientArray) {
                        if (receiver.equals("ALL")) {
                            if (!sender.equals(newClient.getUserName())) {
                                msgFromClient = sender + ": " + content;
                                newClient.sendToMe(msgFromClient.getBytes());
                            } else {
                                msgFromClient = "Me" + ": " + content;
                                sendToMe(msgFromClient.getBytes());
                            }
                        } else if (!receiver.equals("ALL")) {
                            if (newClient.getUserName().equals(receiver)) {
                                msgFromClient = sender + ": " + content;
                                newClient.sendToMe(msgFromClient.getBytes());
                            }
                        }
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }// end of while
    }

    private boolean handshake() throws IOException {
        //PrintWriter out = new PrintWriter(clientSocket.getOutputStream());
        //BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

        HashMap<String, String> keys = new HashMap<>();
        String str;

        //Reading clientSocket handshake / request from clientSocket
        while (!(str = in.readLine()).equals("")) {
            String[] s = str.split(": ");
            if (s.length == 2) {
                keys.put(s[0], s[1]);
            }
        }

        String respondingHash;
        try {
            respondingHash = new BASE64Encoder().encode(MessageDigest.getInstance("SHA-1")
                    .digest((keys.get("Sec-WebSocket-Key")
                            + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11").getBytes()));

        } catch (NoSuchAlgorithmException ex) {
            ex.printStackTrace();
            return false;
        }

        //Write handshake / response to clientSocket
        out.write("HTTP/1.1 101 Switching Protocols\r\n"
                + "Upgrade: websocket\r\n"
                + "Connection: Upgrade\r\n"
                + "Sec-WebSocket-Accept: " + respondingHash + "\r\n"
                + "\r\n");
        out.flush();

        return true;
    }

    public void sendToMe(byte[] msg) throws IOException {
        //System.out.println("Sending to clientSocket");

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        BufferedOutputStream os = new BufferedOutputStream(clientSocket.getOutputStream());

        baos.write(SINGLE_FRAME_UNMASKED);  //fisrt byte(0x81): text type
        baos.write(msg.length); //frame in second byte: text length
        baos.write(msg);  //0x81 + msg length + msg
        baos.flush();
        baos.close();

        os.write(baos.toByteArray(), 0, baos.size());  //send message in bytes
        os.flush();
    }

    public String receiveMessage() throws IOException {

        byte[] buf = readBytes(2); //reading two bytes from clientSocket

        int opcode = buf[0] & 0x0F;  //first byte(0x81) & 0x0F(00001111)

        if (opcode == 8) { //opcode 8 is close connection
            System.out.println("Client left!");

            for (NewClient newClient : server.clientArray) {
                String tempDelete = "DELETE@" + loginName;
                newClient.sendToMe(tempDelete.getBytes());
            }

            server.clientArray.remove(this);

//            in.close();
//            out.close();
//            clientSocket.close();
            closeCon();

            return null;  // error without "return"

        } else {  // opcode == 1 / first byte => text type

            //length of message text
            final int msgLength = getSizeOfMessage(buf[1]);

            buf = readBytes(MASK_SIZE + msgLength); //MASK_SIZE = 4 bytes

            // convert message(byte) to string  // 4 ==> mask size 4 bytes
            buf = unMask(Arrays.copyOfRange(buf, 0, 4), Arrays.copyOfRange(buf, 4, buf.length));
            String message = new String(buf); // message in byte to String
            return message;
        }
    }

    private byte[] readBytes(int numOfBytes) throws IOException {
        byte[] b = new byte[numOfBytes];
        clientSocket.getInputStream().read(b);  //message from clientSocket
        return b;
    }

    // get the length of text message
    private int getSizeOfMessage(byte b) {
        //Must subtract 0x80 from masked frames
        return ((b & 0xFF) - 0x80);
    }

    // extract only text message removing mask 4 bytes
    private byte[] unMask(byte[] mask, byte[] data) {  // mask = 4 bytes
        for (int i = 0; i < data.length; i++) {
            data[i] = (byte) (data[i] ^ mask[i % mask.length]);
        }
        return data;
    }

    public String getUserName() {
        return loginName;
    }

    public void closeCon() throws IOException {
        in.close();
        out.close();
        clientSocket.close();
        return;  // or break;
    }
}

//websocket.html <=== Client
<!DOCTYPE HTML>
<html>
<body>

Instruction;<br><br>

LOGIN: username@ <br>
* from server: <br>
* welcome username<br>
* USERLISTf@numOfUser@user, or<br>
* ADDf@user<br><br>

MESSAGE: username@ALL@hello wolrd <br>
MESSAGE to receiver: username@receiver@hello receiver <br>
* from server: <br>
* username: hello world<br><br>

<button type="button" onclick="connect();">Connect</button>
<button type="button" onclick="connection.close()">Close</button>

<form>
<input type="text" id="msg" />

<button type="button" onclick="sendMsg();">Send message!</button>

<script>
var connection;

function connect() {
    console.log("connection");
    connection = new WebSocket("ws://localhost:4447/");
    // Log errors
connection.onerror = function (error) {
  console.log('WebSocket Error ');
  console.log(error);

};

// Log messages from the server
connection.onmessage = function (e) {
  console.log('Server: ' + e.data);
  alert(e.data);
};

connection.onopen = function (e) {
console.log("Connection open...");
alert("Connection open...");
}

connection.onclose = function (e) {
console.log("Connection closed...");
alert("Connection closed...");
}
}
// end of Log messages from the server

function sendMsg() {
    connection.send(document.getElementById("msg").value);
}

function close() {
    console.log("Closing...");
    connection.close();
}
</script>
</body>

</html>