Interception
All HandlerMapping
implementations support handler interceptors that are useful when
you want to apply specific functionality to certain requests — for example, checking for
a principal. Interceptors must implement HandlerInterceptor
from the
infra.web.mockApi
package with three methods that should provide enough
flexibility to do all kinds of pre-processing and post-processing:
-
preHandle(..)
: Before the actual handler is run -
postHandle(..)
: After the handler is run -
afterCompletion(..)
: After the complete request has finished
The preHandle(..)
method returns a boolean value. You can use this method to break or
continue the processing of the execution chain. When this method returns true
, the
handler execution chain continues. When it returns false, the MockDispatcher
assumes the interceptor itself has taken care of requests (and, for example, rendered an
appropriate view) and does not continue executing the other interceptors and the actual
handler in the execution chain.
See Interceptors in the section on MVC configuration for examples of how to
configure interceptors. You can also register them directly by using setters on individual
HandlerMapping
implementations.
postHandle
method is less useful with @ResponseBody
and ResponseEntity
methods for
which the response is written and committed within the HandlerAdapter
and before
postHandle
. That means it is too late to make any changes to the response, such as adding
an extra header. For such scenarios, you can implement ResponseBodyAdvice
and either
declare it as an Controller Advice bean or configure it directly on
RequestMappingHandlerAdapter
.