public interface AsyncHandlerInterceptor extends HandlerInterceptor
HandlerInterceptorwith a callback method invoked after the start of asynchronous request handling.
When a handler starts an asynchronous request, the DispatcherServlet
exits without invoking
afterCompletion as it
normally does since the results of request handling (e.g. ModelAndView)
is likely not yet ready and will be produced concurrently from another thread.
In such scenarios,
afterConcurrentHandlingStarted(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, java.lang.Object) is invoked instead
allowing implementations to perform tasks such as cleaning up thread bound
attributes before releasing the thread to the Servlet container.
When asynchronous handling completes, the request is dispatched to the
container for further processing. At this stage the DispatcherServlet invokes
To distinguish between the initial request and the subsequent dispatch
after asynchronous handling completes, interceptors can check whether the
is "REQUEST" or "ASYNC".
HandlerInterceptor implementations may be need to do work
when an async request times out or completes with a network error. For such
cases the Servlet container does not dispatch and therefore the
afterCompletion methods will not be invoked.
Instead interceptors can register to track an asynchronous request through
WebAsyncManager. This can be done proactively on every request from
preHandle regardless of whether async request processing will start.
|Modifier and Type||Method and Description|
Called instead of
void afterConcurrentHandlingStarted(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception
afterCompletion, when the a handler is being executed concurrently. Implementations may use the provided request and response but should avoid modifying them in ways that would conflict with the concurrent execution of the handler. A typical use of this method would be to clean thread local variables.