AbstractController (Spring Framework 3.2.1.RELEASE API)
Date: 2013-01-24

org.springframework.web.portlet.mvc

## Class AbstractController

- java.lang.Object
- - org.springframework.context.support.ApplicationObjectSupport
  - - org.springframework.web.portlet.context.PortletApplicationObjectSupport
    - - org.springframework.web.portlet.handler.PortletContentGenerator
      - - org.springframework.web.portlet.mvc.AbstractController

- All Implemented Interfaces:
    Aware, ApplicationContextAware, PortletContextAware, Controller
  Direct Known Subclasses:
    BaseCommandController, ParameterizableViewController, PortletWrappingController

      public abstract class AbstractController
      extends PortletContentGenerator
      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 controlling if a session is required and render caching.

  Workflow (and that defined by interface):

  1. If this is an action request, `handleActionRequest` will be called by the DispatcherPortlet once to perform the action defined by this controller.
  2. If a session is required, try to get it (PortletException if not found).
  3. Call method `handleActionRequestInternal`, (optionally synchronizing around the call on the PortletSession), which should be overridden by extending classes to provide actual functionality to perform the desired action of the controller. This will be executed only once.
  4. For a straight render request, or the render phase of an action request (assuming the same controller is called for the render phase -- see tip below), `handleRenderRequest` will be called by the DispatcherPortlet repeatedly to render the display defined by this controller.
  5. If a session is required, try to get it (PortletException if none found).
  6. It will control caching as defined by the cacheSeconds property.
  7. Call method `handleRenderRequestInternal`, (optionally synchronizing around the call on the PortletSession), which should be overridden by extending classes to provide actual functionality to return `ModelAndView` objects. This will be executed repeatedly as the portal updates the current displayed page.

  Exposed configuration properties (and those defined by interface):

  name | default | description
  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 PortletException will be thrown
  synchronizeOnSession | false | whether the calls to `handleRenderRequestInternal` and `handleRenderRequestInternal` should be synchronized around the PortletSession, to serialize invocations from the same client. No effect if there is no PortletSession.
  cacheSeconds | -1 | indicates the amount of seconds to specify caching is allowed in the render response generatedby this request. 0 (zero) will indicate no caching is allowed at all, -1 (the default) will not override the portlet configuration and any positive number will cause the render response to declare the amount indicated as seconds to cache the content
  renderWhenMinimized | false | whether should be rendered when the portlet is in a minimized state -- will return null for the ModelandView when the portlet is minimized and this is false

  TIP: The controller mapping will be run twice by the PortletDispatcher for action requests -- once for the action phase and again for the render phase. You can reach the render phase of a different controller by simply changing the values for the criteria your mapping is using, such as portlet mode or a request parameter, during the action phase of your controller. This is very handy since redirects within the portlet are apparently impossible. Before doing this, it is usually wise to call `clearAllRenderParameters` and then explicitly set all the parameters that you want the new controller to see. This avoids unexpected parameters from being passed to the render phase of the second controller, such as the parameter indicating a form submit ocurred in an `AbstractFormController`.

  Thanks to Rainer Schmitz and Nick Lothian for their suggestions!

  Since:
    2.0
  Author:
    John A. Lewis, Juergen Hoeller
  See Also:
    `ResourceAwareController`, `EventAwareController`

- - ### Field Summary

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

      `logger`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `AbstractController()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `handleActionRequest(ActionRequest request, ActionResponse response)` Process the action request.
    `protected void` | `handleActionRequestInternal(ActionRequest request, ActionResponse response)` Subclasses are meant to override this method if the controller is expected to handle action requests.
    `ModelAndView` | `handleRenderRequest(RenderRequest request, RenderResponse response)` Process the render request and return a ModelAndView object which the DispatcherPortlet will render.
    `protected ModelAndView` | `handleRenderRequestInternal(RenderRequest request, RenderResponse response)` Subclasses are meant to override this method if the controller is expected to handle render requests.
    `boolean` | `isRenderWhenMinimized()` Return whether controller will render when portlet is minimized.
    `boolean` | `isSynchronizeOnSession()` Return whether controller execution should be synchronized on the session.
    `void` | `setRenderWhenMinimized(boolean renderWhenMinimized)` Set if the controller should render an view when the portlet is in a minimized window.
    `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.portlet.handler.PortletContentGenerator

      `applyCacheSeconds, cacheForSeconds, check, checkAndPrepare, checkAndPrepare, getCacheSeconds, isRequireSession, preventCaching, setCacheSeconds, setRequireSession`

    - ### Methods inherited from class org.springframework.web.portlet.context.PortletApplicationObjectSupport

      `getPortletContext, getTempDir, isContextRequired, setPortletContext`

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

      `getApplicationContext, getMessageSourceAccessor, initApplicationContext, 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 `handleActionRequestInternal` 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 PortletSession 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:
        `handleActionRequestInternal(javax.portlet.ActionRequest, javax.portlet.ActionResponse)`, `HttpSessionMutexListener`, `PortletUtils.getSessionMutex(javax.portlet.PortletSession)`

    - #### isSynchronizeOnSession

          public final boolean isSynchronizeOnSession()

      Return whether controller execution should be synchronized on the session.

    - #### setRenderWhenMinimized

          public final void setRenderWhenMinimized(boolean renderWhenMinimized)

      Set if the controller should render an view when the portlet is in a minimized window. The default is false.
      See Also:
        `PortletRequest.getWindowState()`, `WindowState.MINIMIZED`

    - #### isRenderWhenMinimized

          public final boolean isRenderWhenMinimized()

      Return whether controller will render when portlet is minimized.

    - #### handleActionRequest

          public void handleActionRequest(ActionRequest request,
                                 ActionResponse response)
                                   throws Exception

      Description copied from interface: `Controller`
      Process the action request. There is nothing to return.
      Specified by:
        `handleActionRequest` in interface `Controller`
      Parameters:
        `request` - current portlet action request
        `response` - current portlet action response
      Throws:
        `Exception` - in case of errors

    - #### handleRenderRequest

          public ModelAndView handleRenderRequest(RenderRequest request,
                                         RenderResponse response)
                                           throws Exception

      Description copied from interface: `Controller`
      Process the render request and return a ModelAndView object which the DispatcherPortlet 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:
        `handleRenderRequest` in interface `Controller`
      Parameters:
        `request` - current portlet render request
        `response` - current portlet render response
      Returns:
        a ModelAndView to render, or null if handled directly
      Throws:
        `Exception` - in case of errors

    - #### handleActionRequestInternal

          protected void handleActionRequestInternal(ActionRequest request,
                                         ActionResponse response)
                                              throws Exception

      Subclasses are meant to override this method if the controller is expected to handle action requests. The contract is the same as for `handleActionRequest`.

      The default implementation throws a PortletException.

      Throws:
        `Exception`
      See Also:
        `handleActionRequest(javax.portlet.ActionRequest, javax.portlet.ActionResponse)`, `handleRenderRequestInternal(javax.portlet.RenderRequest, javax.portlet.RenderResponse)`

    - #### handleRenderRequestInternal

          protected ModelAndView handleRenderRequestInternal(RenderRequest request,
                                                 RenderResponse response)
                                                      throws Exception

      Subclasses are meant to override this method if the controller is expected to handle render requests. The contract is the same as for `handleRenderRequest`.

      The default implementation throws a PortletException.

      Throws:
        `Exception`
      See Also:
        `handleRenderRequest(javax.portlet.RenderRequest, javax.portlet.RenderResponse)`, `handleActionRequestInternal(javax.portlet.ActionRequest, javax.portlet.ActionResponse)`