public void selector() throws IOException {
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        Selector selector = Selector.open();
        ServerSocketChannel ssc = ServerSocketChannel.open();
        ssc.configureBlocking(false);
        ssc.socket().bind(new InetSocketAddress(8080));
        ssc.register(selector, SelectionKey.OP_ACCEPT);
        while (true) {
            Set selectedKeys = selector.selectedKeys();
            Iterator it = selectedKeys.iterator();
            while (it.hasNext()) {
                SelectionKey key = (SelectionKey) it.next();
                if ((key.readyOps() & SelectionKey.OP_ACCEPT) == SelectionKey.OP_ACCEPT) {
                    ServerSocketChannel ssChannel = (ServerSocketChannel) key.channel();
                    SocketChannel sc = ssChannel.accept();
                    sc.configureBlocking(false);
                    sc.register(selector, SelectionKey.OP_READ);
                }
                else if ((key.readyOps() & SelectionKey.OP_READ) == SelectionKey.OP_READ) {
                    SocketChannel sc = (SocketChannel) key.channel();
                    while (true) {
                        buffer.clear();
                        int n = sc.read(buffer);
                        if (n <= 0) {
                            break;
                        }
                        buffer.flip();
                    }
                }
                it.remove();
            }
        }
    }