If the "ref" is a reference to a subclass of AbstractMessageRouter, this should resolve automatically (e.g. PayloadTypeRouter).
Otherwise, the method should be resolved if there is a single method annotated with @Router, or finally, if there is a single public method. This is consistent with Splitter and Service Activator - both of which have had this functionality added recently.
This will require a RouterFactoryBean (similar to SplitterFactoryBean).
See discussion on the forum here: http://forum.springframework.org/showthread.php?t=61772