A HandlerInterceptor gets called before the appropriate HandlerAdapter triggers the execution of the handler itself. This mechanism can be used for a large field of preprocessing aspects, e.g. for authorization checks, or common handler behavior like locale or theme changes. Its main purpose is to allow for factoring out repetitive handler code.
In an asynchronous processing scenario, the handler may be executed in a
separate thread while the main thread exits without rendering or invoking the
postHandle and afterCompletion callbacks. When concurrent
handler execution completes, the request is dispatched back in order to
proceed with rendering the model and all methods of this contract are invoked
again. For further options and details see
org.springframework.web.servlet.AsyncHandlerInterceptor
Typically an interceptor chain is defined per HandlerMapping bean, sharing its granularity. To be able to apply a certain interceptor chain to a group of handlers, one needs to map the desired handlers via one HandlerMapping bean. The interceptors themselves are defined as beans in the application context, referenced by the mapping bean definition via its "interceptors" property (in XML: a <list> of <ref>).
HandlerInterceptor is basically similar to a Servlet Filter, but in contrast to the latter it just allows custom pre-processing with the option of prohibiting the execution of the handler itself, and custom post-processing. Filters are more powerful, for example they allow for exchanging the request and response objects that are handed down the chain. Note that a filter gets configured in web.xml, a HandlerInterceptor in the application context.
As a basic guideline, fine-grained handler-related preprocessing tasks are candidates for HandlerInterceptor implementations, especially factored-out common handler code and authorization checks. On the other hand, a Filter is well-suited for request content and view content handling, like multipart forms and GZIP compression. This typically shows when one needs to map the filter to certain content types (e.g. images), or to all requests.
HandlerExecutionChain#getInterceptors, org.springframework.web.servlet.handler.AbstractHandlerMapping#setInterceptors , org.springframework.web.servlet.handler.UserRoleAuthorizationInterceptor , org.springframework.web.servlet.i18n.LocaleChangeInterceptor , org.springframework.web.servlet.theme.ThemeChangeInterceptor , jakarta.servlet.Filter
| Modifier and Type | Method and Description |
|---|---|
| public default void | afterCompletion(HttpServletRequest
current HTTP request request, HttpServletResponse current HTTP response response, Object the handler (or handler, Exception HandlerMethod) that started asynchronous
execution, for type and/or instance examinationany exception thrown on handler execution, if any; this does not
include exceptions that have been handled through an exception resolver ex)Callback after completion of request processing, that is, after rendering the view. |
| public default void | postHandle(HttpServletRequest
current HTTP request request, HttpServletResponse current HTTP response response, Object the handler (or handler, ModelAndView HandlerMethod) that started asynchronous
execution, for type and/or instance examinationthe modelAndView)ModelAndView that the handler returned
(can also be null)Interception point after successful execution of a handler. |
| public default boolean | Returns: true if the execution chain should proceed with the
next interceptor or the handler itself. Else, DispatcherServlet assumes
that this interceptor has already dealt with the response itself.current HTTP request request, HttpServletResponse current HTTP response response, Object chosen handler to execute, for type and/or instance evaluation handler)Interception point before the execution of a handler. |
| afterCompletion | back to summary |
|---|---|
| public default void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception Callback after completion of request processing, that is, after rendering the view. Will be called on any outcome of handler execution, thus allows for proper resource cleanup. Note Will only be called if this interceptor's As with the Note special considerations apply for asynchronous
request processing. For more details see
The default implementation is empty.
| |
| postHandle | back to summary |
|---|---|
| public default void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception Interception point after successful execution of a handler. Called after HandlerAdapter actually invoked the handler, but before the DispatcherServlet renders the view. Can expose additional model objects to the view via the given ModelAndView. DispatcherServlet processes a handler in an execution chain, consisting of any number of interceptors, with the handler itself at the end. With this method, each interceptor can post-process an execution, getting applied in inverse order of the execution chain. Note special considerations apply for asynchronous
request processing. For more details see
The default implementation is empty.
| |
| preHandle | back to summary |
|---|---|
| public default boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception Interception point before the execution of a handler. Called after HandlerMapping determined an appropriate handler object, but before HandlerAdapter invokes the handler. DispatcherServlet processes a handler in an execution chain, consisting of any number of interceptors, with the handler itself at the end. With this method, each interceptor can decide to abort the execution chain, typically sending an HTTP error or writing a custom response. Note special considerations apply for asynchronous
request processing. For more details see
The default implementation returns
| |