netty aio 实现：

public class AIOServer {
    public static void main(String[] args) throws Exception {
        final AsynchronousServerSocketChannel serverChannel =
                AsynchronousServerSocketChannel.open().bind(new InetSocketAddress(9000));

        serverChannel.accept(null, new CompletionHandler<AsynchronousSocketChannel, Object>() {
            @Override
            public void completed(AsynchronousSocketChannel socketChannel, Object attachment) {
                try {
                    // 再此接收客户端连接，如果不写这行代码后面的客户端连接连不上服务端
                    serverChannel.accept(attachment, this);
                    System.out.println(socketChannel.getRemoteAddress());
                    ByteBuffer buffer = ByteBuffer.allocate(1024);
                    socketChannel.read(buffer, buffer, new CompletionHandler<Integer, ByteBuffer>() {
                        @Override
                        public void completed(Integer result, ByteBuffer buffer) {
                            buffer.flip();
                            System.out.println(new String(buffer.array(), 0, result));
                            socketChannel.write(ByteBuffer.wrap("HelloClient".getBytes()));
                        }

                        @Override
                        public void failed(Throwable exc, ByteBuffer buffer) {
                            exc.printStackTrace();
                        }
                    });
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void failed(Throwable exc, Object attachment) {
                exc.printStackTrace();
            }
        });

        Thread.sleep(Integer.MAX_VALUE);
    }
}

client  客户端:

public class AIOClient {

    public static void main(String... args) throws Exception {
        AsynchronousSocketChannel socketChannel = AsynchronousSocketChannel.open();
        socketChannel.connect(new InetSocketAddress("127.0.0.1", 9000)).get();
        socketChannel.write(ByteBuffer.wrap("HelloServer".getBytes()));
        ByteBuffer buffer = ByteBuffer.allocate(512);
        Integer len = socketChannel.read(buffer).get();
        if (len != -1) {
            System.out.println("客户端收到信息：" + new String(buffer.array(), 0, len));
        }
    }
}

serverMultiThread:

public class ServerMultiThread {
    public static void main(String[] args) throws Exception {

        ExecutorService executorService = Executors.newCachedThreadPool();
        //initialSize代表使用几个线程池处理
        AsynchronousChannelGroup threadGroup = AsynchronousChannelGroup.withCachedThreadPool(executorService, 2);

        final AsynchronousServerSocketChannel serverChannel = AsynchronousServerSocketChannel.open(threadGroup)
                .bind(new InetSocketAddress(9000));

        serverChannel.accept(null, new CompletionHandler<AsynchronousSocketChannel, Object>() {
            @Override
            public void completed(AsynchronousSocketChannel socketChannel, Object attachment) {
                try {
                    serverChannel.accep  t(attachment, this);
                    System.out.println(socketChannel.getRemoteAddress());
                    ByteBuffer buffer = ByteBuffer.allocate(1024);
                    socketChannel.read(buffer, buffer, new CompletionHandler<Integer, ByteBuffer>() {
                        @Override
                        public void completed(Integer result, ByteBuffer attachment) {
                            attachment.flip();
                            System.out.println(new String(attachment.array(), 0, result));
                            socketChannel.write(ByteBuffer.wrap("HelloClient".getBytes()));
                        }

                        @Override
                        public void failed(Throwable exc, ByteBuffer attachment) {
                            exc.printStackTrace();
                        }
                    });


                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void failed(Throwable exc, Object attachment) {
                exc.printStackTrace();
            }
        });

        Thread.sleep(Integer.MAX_VALUE);

    }
}