问如何断开客户端与NIO服务器套接字的连接

EN

public EchoServer(int port) throws IOException {
    this.port = port;
    hostAddress = InetAddress.getByName("127.0.0.1");
    selector = initSelector();
    loop();
}

private Selector initSelector() throws IOException {
    Selector socketSelector = SelectorProvider.provider().openSelector();

    ServerSocketChannel serverChannel = ServerSocketChannel.open();
    serverChannel.configureBlocking(false);

    InetSocketAddress isa = new InetSocketAddress(hostAddress, port);
    serverChannel.socket().bind(isa);
    serverChannel.register(socketSelector, SelectionKey.OP_ACCEPT);

    return socketSelector;
}

private void loop() {
    for (;true;) {
        try {
            selector.select();
            Iterator<SelectionKey> selectedKeys = selector.selectedKeys()
                    .iterator();
            while (selectedKeys.hasNext()) {
                SelectionKey key = selectedKeys.next();
                selectedKeys.remove();

                if (!key.isValid()) {
                    continue;
                }

                // Check what event is available and deal with it
                if (key.isAcceptable()) {
                    accept(key);
                } else if (key.isReadable()) {
                    read(key);
                } else if (key.isWritable()) {
                    write(key);
                }
            }
            Thread.sleep(1000);
            timestamp++;
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(1);
        }       
    }
}