Content negotiation is a mechanism that makes it possible to serve different representations of the same resource. For example, so far we have shown our product detail page in a JSP representation. What if we want to represent the same content in an XML format. Similarly, what if we want the same content in a JSON format? Here comes Spring MVC's ContentNegotiatingViewResolver (org.springframework.web.servlet.view.ContentNegotiatingViewResolver) to help us.
The XML and JSON formats are popular data interchange formats that are heavily used in web service communications. Using ContentNegotiatingViewResolver, we can incorporate many Views such as MappingJacksonJsonView (for JSON) and MarshallingView (for XML) to represent the same product information in a XML or JSON format.