服务端

public class NioServer {
    public static void main(String[] args) {
        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
        try (ServerSocketChannel ssc = ServerSocketChannel.open()) {
            ArrayList<SocketChannel> socketChannels = new ArrayList<>();
            ssc.bind(new InetSocketAddress(8888));
            while (true) {
                ssc.configureBlocking(false);
                System.out.println("before accept");
                SocketChannel socketChannel = ssc.accept();
                if (socketChannel != null) {
                    socketChannels.add(socketChannel);
                }
                for (SocketChannel socketChannel1 : socketChannels) {
                    socketChannel1.configureBlocking(false);
                    System.out.println("before reading");
                    int read = socketChannel1.read(byteBuffer);
                    if (read > 0) {
                        byteBuffer.flip();
                        String s = StandardCharsets.UTF_8.decode(byteBuffer).toString();
                        byteBuffer.clear();
                        System.out.println(s);
                    }
                }
            }

        } catch (IOException e) {
        }
    }
}