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Spring's CachingConnectionFactory uses the amqp-client ConnectionFactory. See "Configuring the Underlying Client Connection Factory" [1].
You can use Spring's RabbitConnectionFactoryBean to create the amqp-client connection factory (call setUseNio(true)) .
You can then pass it into the CachingConnectionFactory via a constructor. Or you can use
cachingConnectionFactory.getRabbitConnectionFactory().useNio();
to reconfigure the underlying factory before opening a connection.