The Spring Framework

## org.springframework.web.portlet.mvc
Interface Controller

All Known Implementing Classes:
  AbstractCommandController, AbstractController, AbstractFormController, AbstractWizardFormController, BaseCommandController, ParameterizableViewController, PortletModeNameViewController, PortletWrappingController, SimpleFormController

    public interface Controller

Base portlet Controller interface, representing a component that receives RenderRequest/RenderResponse and ActionRequest/ActionResponse like a `Portlet` but is able to participate in an MVC workflow.

Any implementation of the portlet Controller interface should be a reusable, threadsafe class, capable of handling multiple portlet requests throughout the lifecycle of an application. To be able to configure Controller(s) in an easy way, Controllers are usually JavaBeans.

Workflow:

After the DispatcherPortlet has received a request and has done its work to resolve locales, themes and suchlike, it tries to resolve a Controller to handle that request, using a `HandlerMapping`. When a Controller has been found, the `handleRenderRequest` or `handleActionRequest` method will be invoked, which is responsible for handling the actual request and - if applicable - returning an appropriate ModelAndView. So actually, these method are the main entrypoint for the `DispatcherPortlet` which delegates requests to controllers. These method - and also this interface - should preferrably not be implemented by custom controllers directly, since abstract controllers also provided by this package already provide a lot of functionality for typical use cases in portlet applications. A few examples of those controllers: `AbstractController`, `AbstractCommandController`, `AbstractFormController`, `SimpleFormController`.

So basically any direct implementation of the Controller interface just handles RenderRequests/ActionRequests and should return a ModelAndView, to be further used by the DispatcherPortlet. Any additional functionality such as optional validation, form handling, etc should be obtained through extending one of the abstract controller classes mentioned above.

Since:
  2.0
Author:
  William G. Thompson, Jr., John A. Lewis
See Also:
  `SimpleControllerHandlerAdapter`, `AbstractController`, `AbstractCommandController`, `AbstractFormController`, `SimpleFormController`, `ApplicationContextAware`, `ResourceLoaderAware`, `PortletContextAware`

Method Summary
`void` `handleActionRequest(javax.portlet.ActionRequest request, javax.portlet.ActionResponse response)` Process the action request.
`ModelAndView` `handleRenderRequest(javax.portlet.RenderRequest request, javax.portlet.RenderResponse response)` Process the render request and return a ModelAndView object which the DispatcherPortlet will render.

Method Detail

### handleActionRequest

    void handleActionRequest(javax.portlet.ActionRequest request,
                             javax.portlet.ActionResponse response)
                             throws Exception

  Process the action request. There is nothing to return.

  Parameters:
    `request` - current portlet action request
    `response` - current portlet action response
  Throws:
    `Exception` - in case of errors

### handleRenderRequest

    ModelAndView handleRenderRequest(javax.portlet.RenderRequest request,
                                     javax.portlet.RenderResponse response)
                                     throws Exception

  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.

  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

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