Java nio在reactor模式下的使用示例

Java NIO在Reactor模式下的使用示例可以参考下面的代码：

import java.io.IOException;
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 Reactor implements Runnable {
    private final ServerSocketChannel serverSocket;
    private final Selector selector;

    public Reactor(int port) throws IOException {
        selector = Selector.open();
        serverSocket = ServerSocketChannel.open();
        serverSocket.bind(new InetSocketAddress(port));
        serverSocket.configureBlocking(false);
        SelectionKey sk = serverSocket.register(selector, SelectionKey.OP_ACCEPT);
        sk.attach(new Acceptor());
    }

    @Override
    public void run() {
        try {
            while (!Thread.interrupted()) {
                selector.select();
                Set<SelectionKey> selected = selector.selectedKeys();
                Iterator<SelectionKey> it = selected.iterator();
                while (it.hasNext()) {
                    SelectionKey sk = it.next();
                    dispatch(sk);
                }
                selected.clear();
            }
        } catch (IOException ex) {
            // handle exception
        }
    }

    private void dispatch(SelectionKey sk) {
        Runnable r = (Runnable) sk.attachment();
        if (r != null) {
            r.run();
        }
    }

    private class Acceptor implements Runnable {
        @Override
        public void run() {
            try {
                SocketChannel channel = serverSocket.accept();
                if (channel != null) {
                    new Handler(selector, channel);
                }
            } catch (IOException ex) {
                // handle exception
            }
        }
    }

    private class Handler implements Runnable {
        private final SocketChannel channel;
        private final SelectionKey sk;

        private ByteBuffer buffer = ByteBuffer.allocate(1024);

        public Handler(Selector selector, SocketChannel channel) throws IOException {
            this.channel = channel;
            channel.configureBlocking(false);
            sk = channel.register(selector, SelectionKey.OP_READ);
            sk.attach(this);
        }

        @Override
        public void run() {
            try {
                int len = channel.read(buffer);
                if (len < 0) {
                    channel.close();
                    return;
                }
                buffer.flip();
                byte[] bytes = new byte[buffer.remaining()];
                buffer.get(bytes);
                String request = new String(bytes);
                // process request
                // ...
                buffer.clear();
            } catch (IOException ex) {
                // handle exception
            }
        }
    }
}

这是一个简单的Reactor模式的示例，它使用Java NIO实现了一个基于事件驱动的服务器。在这个示例中，Reactor对象作为主线程运行，它负责监听客户端连接事件，并将事件分发给对应的Handler对象处理。Acceptor对象负责接受客户端连接，并将新连接注册到Selector对象中。Handler对象负责处理客户端请求，它在接收到客户端数据后进行处理，并将响应发送回客户端。这个示例中的Handler对象是单线程处理请求的，如果需要支持并发处理请求，可以将Handler对象改为线程池模式。