자바에서 nio는 무엇을 의미합니까?

<code class="java">import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

public class EchoServer {

    public static void main(String[] args) throws Exception {
        ServerSocketChannel serverChannel = ServerSocketChannel.open();
        Selector selector = Selector.open();

        serverChannel.configureBlocking(false);
        serverChannel.register(selector, SelectionKey.OP_ACCEPT);

        while (true) {
            selector.select();
            Set<SelectionKey> selectedKeys = selector.selectedKeys();
            Iterator<SelectionKey> iterator = selectedKeys.iterator();

            while (iterator.hasNext()) {
                SelectionKey key = iterator.next();

                if (key.isAcceptable()) {
                    SocketChannel clientChannel = serverChannel.accept();
                    clientChannel.configureBlocking(false);
                    clientChannel.register(selector, SelectionKey.OP_READ);
                }
                else if (key.isReadable()) {
                    // 处理客户端请求...
                }

                iterator.remove();
            }
        }
    }
}</code>