public class Acceptor implements Runnable {
    private Selector selector;

    private ServerSocketChannel serverSocketChannel;

    public Acceptor(Selector selector, ServerSocketChannel serverSocketChannel) {
        this.selector = selector;
        this.serverSocketChannel = serverSocketChannel;
    }

    @Override
    public void run() {
        try {
            SocketChannel socketChannel = serverSocketChannel.accept();
            System.out.println("有客户端连接上来了," + socketChannel.getRemoteAddress());
            socketChannel.configureBlocking(false);
            SelectionKey selectionKey = socketChannel.register(selector, SelectionKey.OP_READ);
            // 修改此处就可以切换成多线程模型了
            selectionKey.attach(new WorkerHandlerThreadPool(socketChannel));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public class WorkerHandlerThreadPool implements Runnable {

    static ExecutorService pool = Executors.newFixedThreadPool(2);

    private SocketChannel socketChannel;

    public WorkerHandlerThreadPool(SocketChannel socketChannel) {
        this.socketChannel = socketChannel;
    }

    @Override
    public void run() {
        try {
            System.out.println("WorkerHandlerThreadPool thread :" + Thread.currentThread().getName());
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            socketChannel.read(buffer);
            pool.execute(new Process(socketChannel, buffer));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public class Process implements Runnable {

    private SocketChannel socketChannel;

    private ByteBuffer byteBuffer;

    public Process(SocketChannel socketChannel, ByteBuffer byteBuffer) {
        this.byteBuffer = byteBuffer;
        this.socketChannel = socketChannel;
    }

    @Override
    public void run() {
        try {
            System.out.println("sleep 10s");
            Thread.sleep(10000);
            System.out.println("process thread:" + Thread.currentThread().getName());
            String message = new String(byteBuffer.array(), StandardCharsets.UTF_8);
            System.out.println(socketChannel.getRemoteAddress() + "发来的消息是:" + message);
            socketChannel.write(ByteBuffer.wrap("你的消息我收到了".getBytes(StandardCharsets.UTF_8)));
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

/**
    有客户端连接上来了,/127.0.0.1:64797
    有客户端连接上来了,/127.0.0.1:64800
    WorkerHandlerThreadPool thread :main
    sleep 10s
    process thread:pool-1-thread-1
    /127.0.0.1:64797发来的消息是:I am one
    WorkerHandlerThreadPool thread :main
    sleep 10s
    WorkerHandlerThreadPool thread :main
    sleep 10s
    process thread:pool-1-thread-2
    /127.0.0.1:64800发来的消息是:I am two
    process thread:pool-1-thread-1
    /127.0.0.1:64797发来的消息是:hah
*/