4.1springmvc返回json问题

用的hibernate+springmvc+spring 都是4.0+的，用了jackson-annotation,jack-core,jackson-databind,都是2.6.0版本，开启了mvc:annotation-driven,然而返回json总是报406：The resource identified by this request is only capable of generating responses with characteristics not acceptable according to the request "accept" headers.