很诡异的nio非阻塞通信

我先把代码贴出来吧

public class AServer {
	public static void main(String[] args) throws Exception {
		ServerSocketChannel server = ServerSocketChannel.open();
		server.configureBlocking(false);
		server.socket().bind(new InetSocketAddress(8080));
		Selector selector = Selector.open();
		server.register(selector, SelectionKey.OP_ACCEPT);
		
		while (true) {
			selector.select();
			System.out.println("selector.select()---------" + selector.select());
			//readKeys集合
			Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
			while (iter.hasNext()) {
				SelectionKey key = iter.next();
				iter.remove();
				
				if (key.isAcceptable()) {
					System.out.println("acceptable");
//					ServerSocketChannel ssc = (ServerSocketChannel) key.channel();
					SocketChannel client = server.accept();
					client.configureBlocking(false);
					client.register(selector, SelectionKey.OP_READ);
				} else if (key.isReadable()) {
					System.out.println("this server is readable");
				}
			}
		}
	}
}

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public class AClient {
	public static void main(String[] args) throws Exception {
		SocketChannel client = SocketChannel.open();
		client.configureBlocking(false);
		Selector selector = Selector.open();
		client.register(selector, SelectionKey.OP_CONNECT);
		client.connect(new InetSocketAddress("localhost", 8080));
		
		while (true) {
			selector.select();
			//readKeys
			Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
			while (iter.hasNext()) {
				SelectionKey key = iter.next();
				iter.remove();
				
				if (key.isConnectable()) {
//					System.out.println("connnect");
					SocketChannel socket = (SocketChannel) key.channel();
					socket.configureBlocking(false);
//					socket.register(selector, SelectionKey.OP_READ);
//					System.out.println("client is connected");
				} else if (key.isReadable()) {
					System.out.println("client is read");
				}
			}
		}
	}
}

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我注释掉AServer中的System.out.println("acceptable")和AClient中的System.out.println("connnect")，在AServer中就不能打印System.out.println("this server is readable")这句了。

还有两个问题就是我没有注掉System.out.println("acceptable")和System.out.println("connnect")时，AServer中一直会执行System.out.println("this server is readable");AClient也会一直执行System.out.println("connnect")，我感到疑惑的是执行了

SelectionKey key = iter.next();
				iter.remove();

这个之后，key不是被删除了么，不应该出现很多次

if (key.isConnectable()) {
//					System.out.println("connnect");
					SocketChannel socket = (SocketChannel) key.channel();
					socket.configureBlocking(false);
//					socket.register(selector, SelectionKey.OP_READ);
//					System.out.println("client is connected");
				} 

这里面打印的内容呀

还有个疑惑就是在AServer中

SocketChannel client = server.accept();
					client.configureBlocking(false);
					client.register(selector, SelectionKey.OP_READ);

执行了这段代码，client注册SelectionKey.OP_READ为可读的操作，是服务器端和客户端的key都是Readable可读的？如果是可读的为什么在AClient中没有打印

System.out.println("client is read");

这句呀。

由于才接触到nio这块，不是很熟悉，大家可以帮我看看么，感谢ing