[Ch15] Server simplification and cleanup

import java.nio.channels.ServerSocketChannel;

import java.nio.channels.SocketChannel;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

  public void run() {

    ByteBuffer buffer = ByteBuffer.allocate(32);

    buffer.clear();

    System.out.println("running");

    try {

      while (clientSocket.isOpen()) {

        System.out.println("clientSocket = " + clientSocket.isOpen());

        clientSocket.read(buffer);

        String message = new String(buffer.array()).trim();

        System.out.println("read " + message);

        buffer.flip();

  }

  public void tellEveryone(ByteBuffer message) {

    Iterator<SocketChannel> it = clientOutputStreams.iterator();

    while (it.hasNext()) {

      SocketChannel next = it.next();

      System.out.println("Telling: " + next);

    for (SocketChannel channel : clientOutputStreams) {

      try {

        next.write(message);

        channel.write(message);

        message.rewind();

      } catch (Exception ex) {

        ex.printStackTrace();