如何使用 Java NIO 优化 Java 函数的网络 I/O 性能？

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

public class NIOChatServer {

    public static void main(String[] args) throws IOException {
        // 创建 ServerSocketChannel
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.bind(new InetSocketAddress(9090));
        serverSocketChannel.configureBlocking(false);

        // 创建 Selector
        Selector selector = Selector.open();

        // 将 ServerSocketChannel 注册到 Selector 中
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

        while (true) {
            // 阻塞选择键
            selector.select();

            // 获取已就绪的 SelectionKey 集合
            Set<SelectionKey> selectionKeys = selector.selectedKeys();

            Iterator<SelectionKey> iterator = selectionKeys.iterator();

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

                if (selectionKey.isAcceptable()) {
                    // 新连接，接受并注册到 Selector 中
                    SocketChannel socketChannel = serverSocketChannel.accept();
                    socketChannel.configureBlocking(false);
                    socketChannel.register(selector, SelectionKey.OP_READ);
                } else if (selectionKey.isReadable()) {
                    // 已收到数据，读取并广播
                    SocketChannel socketChannel = (SocketChannel) selectionKey.channel();
                    ByteBuffer buffer = ByteBuffer.allocate(1024);
                    int read = socketChannel.read(buffer);
                    if (read > 0) {
                        String message = new String(buffer.array(), 0, read);
                        broadcast(selector, socketChannel, message);
                    }
                }

                // 移除处理过的 SelectionKey
                iterator.remove();
            }
        }
    }

    public static void broadcast(Selector selector, SocketChannel sourceChannel, String message)
            throws IOException {
        // 获取 Selector 中所有的已注册 Channel
        Set<SelectionKey> selectionKeys = selector.keys();

        for (SelectionKey selectionKey : selectionKeys) {
            // 排除源 Channel
            if (selectionKey.channel() instanceof SocketChannel
                    && selectionKey.channel() != sourceChannel) {
                SocketChannel socketChannel = (SocketChannel) selectionKey.channel();
                ByteBuffer buffer = ByteBuffer.wrap(message.getBytes());
                socketChannel.write(buffer);
            }
        }
    }
}