@ResponseBody does not produce json

@ResponseBody does not produce json

I have the Controller class which gets executred. But I don't get any
response.
I am using <mvc:annotation-driven /> and have jackson-core-asl-1.9.13.jar
and jackson-mapper-asl-1.9.13.jar in \WEB-INF\lib.
@RequestMapping(value = "/persons.htm", method = RequestMethod.GET,
produces={"application/json"})
public @ResponseBody List<Person> getPersons() {
Collection<Person> persons = personService.findPersons("Smith"); //
requesr comes here
System.out.println("persons " + persons);
}