NIO DiscardServer

DiscardServer.java

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Set;

class Server implements Runnable {
    private int port;
    private final Selector selector;
    private final ServerSocketChannel serverChannel;

    Server(int port) throws IOException {
        this.port = port;
        selector = Selector.open();
        serverChannel = ServerSocketChannel.open();
        serverChannel.configureBlocking(false);
        SelectionKey selectionKey = serverChannel.bind(new InetSocketAddress(port)).register(
                selector, SelectionKey.OP_ACCEPT);
        selectionKey.attach(new Acceptor());
    }

    @Override
    public void run() {
        try {
            while (!Thread.interrupted()) {
                selector.select();
                Set<SelectionKey> selectedKeys = selector.selectedKeys();
                for (SelectionKey key : selectedKeys) {
                    dispatch(key);
                }
                selectedKeys.clear();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void dispatch(SelectionKey key) {
        Runnable r = (Runnable) key.attachment();
        if (r != null) {
            r.run();
        }
    }

    private class Acceptor implements Runnable{
        @Override
        public void run() {
            try {
                SocketChannel channel = serverChannel.accept();
                if (channel != null) {
                    new Handler(selector, channel);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

class Handler implements Runnable{
    private SocketChannel channel;
    private SelectionKey selectionKey;
    private ByteBuffer in = ByteBuffer.allocate(2048);

    Handler(Selector selector, SocketChannel channel) throws IOException {
        this.channel = channel;
        channel.configureBlocking(false);
        selectionKey = channel.register(selector, SelectionKey.OP_READ);
        selectionKey.attach(this);
        selector.wakeup();
    }

    @Override
    public void run() {
        byte[] bytes = new byte[1024];
        int len;
        try {
            channel.read(in);
            in.flip();
            while ((len = in.remaining()) > 0) {
                in.get(bytes, 0, Math.min(len, 1024));
                System.out.print("received: " + new String(bytes));
            }
            in.clear();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public class DiscardServer {

    private static Thread thread;

    public static void main(String[] args) throws IOException, InterruptedException {
        int port;
        if (args.length == 1) {
            port = Integer.valueOf(args[0]);
        } else {
            port = 8888;
        }
        thread = new Thread(new Server(port));
        thread.start();
        thread.join();
    }
}