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:

ApplicationContextAware, Controller

Direct Known Subclasses:

AbstractUrlViewController, BaseCommandController, MultiActionController, ParameterizableViewController, ServletForwardingController, ServletWrappingController

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):

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 cacheSeconds propery
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, derived controller can - without fear of Nullpointers - 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

See Also:

WebContentInterceptor

Field Summary

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

HEADER_CACHE_CONTROL, HEADER_EXPIRES, HEADER_PRAGMA, METHOD_GET, METHOD_HEAD, METHOD_POST

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

logger

Constructor Summary

AbstractController()

Method Summary

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

applyCacheSeconds, applyCacheSeconds, cacheForSeconds, cacheForSeconds, checkAndPrepare, checkAndPrepare, getCacheSeconds, getSupportedMethods, isRequireSession, isUseCacheControlHeader, isUseExpiresHeader, preventCaching, setCacheSeconds, setRequireSession, setSupportedMethods, setUseCacheControlHeader, setUseExpiresHeader

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

getServletContext, getTempDir, getWebApplicationContext, isContextRequired

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

getApplicationContext, getMessageSourceAccessor, initApplicationContext, 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()

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

public final ModelAndView handleRequest(HttpServletRequest request,
                                        HttpServletResponse response)
                                 throws 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, thus there is 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:

Exception - in case of errors

handleRequestInternal

protected abstract ModelAndView handleRequestInternal(HttpServletRequest request,
                                                      HttpServletResponse response)
                                               throws Exception

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

Throws:

Exception

See Also:

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