public abstract class AbstractController extends WebContentGenerator implements Controller
Convenient superclass for controller implementations, using the Template Method design pattern.
As stated in the Controller
interface, a lot of functionality is already provided by certain abstract
base controllers. The AbstractController is one of the most important
abstract base controller providing basic features such as the generation
of caching headers and the enabling or disabling of
supported methods (GET/POST).
Workflow
(and that defined by interface):
handleRequest()
will be called by the DispatcherServlethandleRequestInternal()
(optionally synchronizing around the call on the HttpSession),
which should be implemented by extending classes to provide actual
functionality to return ModelAndView objects.Exposed configuration properties
(and those defined by interface):
| name | default | description |
| supportedMethods | GET,POST | comma-separated (CSV) list of methods supported by this controller, such as GET, POST and PUT |
| requireSession | false | whether a session should be required for requests to be able to be handled by this controller. This ensures that derived controller can - without fear of null pointers - call request.getSession() to retrieve a session. If no session can be found while processing the request, a ServletException will be thrown |
| cacheSeconds | -1 | indicates the amount of seconds to include in the cache header for the response following on this request. 0 (zero) will include headers for no caching at all, -1 (the default) will not generate any headers and any positive number will generate headers that state the amount indicated as seconds to cache the content |
| synchronizeOnSession | false | whether the call to handleRequestInternal should be
synchronized around the HttpSession, to serialize invocations
from the same client. No effect if there is no HttpSession.
|
WebContentInterceptorMETHOD_GET, METHOD_HEAD, METHOD_POSTlogger| Constructor and Description |
|---|
AbstractController() |
| Modifier and Type | Method and Description |
|---|---|
ModelAndView |
handleRequest(HttpServletRequest request,
HttpServletResponse response)
Process the request and return a ModelAndView object which the DispatcherServlet
will render.
|
protected abstract ModelAndView |
handleRequestInternal(HttpServletRequest request,
HttpServletResponse response)
Template method.
|
boolean |
isSynchronizeOnSession()
Return whether controller execution should be synchronized on the session.
|
void |
setSynchronizeOnSession(boolean synchronizeOnSession)
Set if controller execution should be synchronized on the session,
to serialize parallel invocations from the same client.
|
applyCacheSeconds, applyCacheSeconds, cacheForSeconds, cacheForSeconds, checkAndPrepare, checkAndPrepare, getCacheSeconds, getSupportedMethods, isAlwaysMustRevalidate, isRequireSession, isUseCacheControlHeader, isUseCacheControlNoStore, isUseExpiresHeader, preventCaching, setAlwaysMustRevalidate, setCacheSeconds, setRequireSession, setSupportedMethods, setUseCacheControlHeader, setUseCacheControlNoStore, setUseExpiresHeadergetServletContext, getTempDir, getWebApplicationContext, initApplicationContext, initServletContext, isContextRequired, setServletContextgetApplicationContext, getMessageSourceAccessor, initApplicationContext, requiredContextClass, setApplicationContextpublic final void setSynchronizeOnSession(boolean synchronizeOnSession)
More specifically, the execution of the handleRequestInternal
method will get synchronized if this flag is "true". The best available
session mutex will be used for the synchronization; ideally, this will
be a mutex exposed by HttpSessionMutexListener.
The session mutex is guaranteed to be the same object during
the entire lifetime of the session, available under the key defined
by the SESSION_MUTEX_ATTRIBUTE constant. It serves as a
safe reference to synchronize on for locking on the current session.
In many cases, the HttpSession reference itself is a safe mutex as well, since it will always be the same object reference for the same active logical session. However, this is not guaranteed across different servlet containers; the only 100% safe way is a session mutex.
public final boolean isSynchronizeOnSession()
public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception
Controllernull return value is not an error: It indicates that
this object completed request processing itself, thus there is no ModelAndView
to render.handleRequest in interface Controllerrequest - current HTTP requestresponse - current HTTP responsenull if handled directlyException - in case of errorsprotected abstract ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws Exception
handleRequest.