Java I/O 스트림의 NIO API는 어떻게 작동합니까?

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.ArrayList;
import java.util.List;

public class NIOServer {

    private static final int PORT = 8080;
    private static List<SocketChannel> connectedSockets = new ArrayList<>();

    public static void main(String[] args) throws IOException {

        // 创建服务器套接字通道
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();

        // 将服务器通道绑定到端口
        serverSocketChannel.bind(new InetSocketAddress(PORT));

        // 设置非阻塞模式
        serverSocketChannel.configureBlocking(false);

        // 获取选择器
        Selector selector = Selector.open();

        // 将服务器通道注册到选择器，感兴趣的可接受事件
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

        // 事件循环
        while (true) {

            // 阻塞，直到至少有一个通道准备好
            int readyChannels = selector.select();

            // 如果没有准备好的通道，则继续
            if (readyChannels == 0) {
                continue;
            }

            // 处理准备好的通道
            for (SelectionKey key : selector.selectedKeys()) {

                // 可接受事件
                if (key.isAcceptable()) {

                    // 接受传入的连接
                    SocketChannel socketChannel = serverSocketChannel.accept();

                    // 设置非阻塞模式
                    socketChannel.configureBlocking(false);

                    // 将套接字通道注册到选择器，感兴趣的可读事件
                    socketChannel.register(selector, SelectionKey.OP_READ);

                    // 添加到已连接套接字列表
                    connectedSockets.add(socketChannel);
                }

                // 可读事件
                else if (key.isReadable()) {

                    SocketChannel socketChannel = (SocketChannel) key.channel();

                    // 读取数据
                    ByteBuffer buffer = ByteBuffer.allocate(1024);
                    int bytesRead = socketChannel.read(buffer);

                    // 如果读取到EOF，则关闭套接字
                    if (bytesRead == -1) {
                        socketChannel.close();
                        connectedSockets.remove(socketChannel);
                    }

                    // 处理读取到的数据
                    // ...

                }
            }

            // 清除已处理的键
            selector.selectedKeys().clear();
        }
    }
}