java.nio.channels.NotYetConnectedException: null

最近在学习Java AIO操作时，出现如下异常

比较奇怪的是，该异常仅仅在两个操作间隔非常短的时候，才会出现。根据调式与排查，发现问题出现在AsynchronousSocketChannel的connect方法调用上。

/**
     * Connects this channel.
     *
     * 
 This method initiates an operation to connect this channel. This
     * method behaves in exactly the same manner as the {@link
     * #connect(SocketAddress, Object, CompletionHandler)} method except that
     * instead of specifying a completion handler, this method returns a {@code
     * Future} representing the pending result. The {@code Future}'s {@link
     * Future#get() get} method returns {@code null} on successful completion.
     *
     * @param   remote
     *          The remote address to which this channel is to be connected
     *
     * @return  A {@code Future} object representing the pending result
     *
     * @throws  UnresolvedAddressException
     *          If the given remote address is not fully resolved
     * @throws  UnsupportedAddressTypeException
     *          If the type of the given remote address is not supported
     * @throws  AlreadyConnectedException
     *          If this channel is already connected
     * @throws  ConnectionPendingException
     *          If a connection operation is already in progress on this channel
     * @throws  SecurityException
     *          If a security manager has been installed
     *          and it does not permit access to the given remote endpoint
     */
    public abstract Future<Void> connect(SocketAddress remote);

此处connect为异步方法，调用connect时，可能并没有成功建立连接，从而导致出现上述异常。
解决措施：
1、显示调用get，通过阻塞的方式，获取连接。

2、通过如下connect方法，通过第三个参数，在完成连接连接时，进行后续操作。

public abstract <A> void connect(SocketAddress remote,
                                     A attachment,
                                     CompletionHandler<Void,? super A> handler);