org.springframework.web.servlet.mvc

Class AbstractController

java.lang.Object

org.springframework.context.support.ApplicationObjectSupport

org.springframework.web.context.support.WebApplicationObjectSupport

org.springframework.web.servlet.support.WebContentGenerator

org.springframework.web.servlet.mvc.AbstractController

All Implemented Interfaces:

Aware, ApplicationContextAware, ServletContextAware, Controller

Direct Known Subclasses:

AbstractUrlViewController, ParameterizableViewController, ServletForwardingController, ServletWrappingController

public abstract class AbstractController
extends WebContentGenerator
implements Controller

Convenient superclass for controller implementations, using the Template Method design pattern.

Workflow (and that defined by interface):

1. handleRequest() will be called by the DispatcherServlet
2. Inspection of supported methods (ServletException if request method is not support)
3. If session is required, try to get it (ServletException if not found)
4. Set caching headers if needed according to the cacheSeconds property
5. Call abstract method handleRequestInternal() (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.

Author:

Rod Johnson, Juergen Hoeller, Rossen Stoyanchev

See Also:

WebContentInterceptor

Field Summary

Fields inherited from class org.springframework.web.servlet.support.WebContentGenerator

HEADER_CACHE_CONTROL, METHOD_GET, METHOD_HEAD, METHOD_POST

Fields inherited from class org.springframework.context.support.ApplicationObjectSupport

logger

Constructor Summary

Constructors

Constructor and Description
AbstractController() Create a new AbstractController which supports HTTP methods GET, HEAD and POST by default.
AbstractController(boolean restrictDefaultSupportedMethods) Create a new AbstractController.

Method Summary

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.

Methods inherited from class org.springframework.web.servlet.support.WebContentGenerator

applyCacheControl, applyCacheSeconds, applyCacheSeconds, cacheForSeconds, cacheForSeconds, checkAndPrepare, checkAndPrepare, checkRequest, getAllowHeader, getCacheControl, getCacheSeconds, getSupportedMethods, getVaryByRequestHeaders, isAlwaysMustRevalidate, isRequireSession, isUseCacheControlHeader, isUseCacheControlNoStore, isUseExpiresHeader, prepareResponse, preventCaching, setAlwaysMustRevalidate, setCacheControl, setCacheSeconds, setRequireSession, setSupportedMethods, setUseCacheControlHeader, setUseCacheControlNoStore, setUseExpiresHeader, setVaryByRequestHeaders

Methods inherited from class org.springframework.web.context.support.WebApplicationObjectSupport

getServletContext, getTempDir, getWebApplicationContext, initApplicationContext, initServletContext, isContextRequired, setServletContext

Methods inherited from class org.springframework.context.support.ApplicationObjectSupport

getApplicationContext, getMessageSourceAccessor, initApplicationContext, obtainApplicationContext, requiredContextClass, setApplicationContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AbstractController

public AbstractController()

Create a new AbstractController which supports HTTP methods GET, HEAD and POST by default.

AbstractController

public AbstractController(boolean restrictDefaultSupportedMethods)

Create a new AbstractController.

Parameters:

restrictDefaultSupportedMethods - true if this controller should support HTTP methods GET, HEAD and POST by default, or false if it should be unrestricted

Since:

4.3

Method Detail

setSynchronizeOnSession

public final void setSynchronizeOnSession(boolean synchronizeOnSession)

Set if controller execution should be synchronized on the session, to serialize parallel invocations from the same client.

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.

See Also:

handleRequestInternal(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse), HttpSessionMutexListener, WebUtils.getSessionMutex(javax.servlet.http.HttpSession)

isSynchronizeOnSession

public final boolean isSynchronizeOnSession()

Return whether controller execution should be synchronized on the session.

handleRequest

@Nullable
public ModelAndView handleRequest(HttpServletRequest request,
                                            HttpServletResponse response)
                                     throws java.lang.Exception

Description copied from interface: Controller

Process the request and return a ModelAndView object which the DispatcherServlet will render. A null return value is not an error: it indicates that this object completed request processing itself and that there is therefore no ModelAndView to render.

Specified by:

handleRequest in interface Controller

Parameters:

request - current HTTP request

response - current HTTP response

Returns:

a ModelAndView to render, or null if handled directly

Throws:

java.lang.Exception - in case of errors

handleRequestInternal

@Nullable
protected abstract ModelAndView handleRequestInternal(HttpServletRequest request,
                                                                HttpServletResponse response)
                                                         throws java.lang.Exception

Template method. Subclasses must implement this. The contract is the same as for handleRequest.

Throws:

java.lang.Exception

See Also:

handleRequest(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)