The Spring Framework

## org.springframework.web.struts
Class DelegatingRequestProcessor

    java.lang.Object
      org.apache.struts.action.RequestProcessor
          org.springframework.web.struts.DelegatingRequestProcessor

    public class DelegatingRequestProcessor

extends RequestProcessor

Subclass of Struts's default `RequestProcessor` that looks up Spring-managed Struts `Actions` defined in `ContextLoaderPlugIn's` `WebApplicationContext` (or, as a fallback, in the root `WebApplicationContext`).

In the Struts config file, you can either specify the original `Action` class (as when generated by XDoclet), or no `Action` class at all. In any case, Struts will delegate to an `Action` bean in the `ContextLoaderPlugIn` context.

    <action path="/login" type="myapp.MyAction"/>

or

    <action path="/login"/>

The name of the `Action` bean in the `WebApplicationContext` will be determined from the mapping path and module prefix. This can be customized by overriding the `determineActionBeanName(org.apache.struts.action.ActionMapping)` method.

Example:

- mapping path "/login" -> bean name "/login"
- mapping path "/login", module prefix "/mymodule" -> bean name "/mymodule/login"

A corresponding bean definition in the `ContextLoaderPlugin` context would look as follows; notice that the `Action` is now able to leverage fully Spring's configuration facilities:

     <bean name="/login" class="myapp.MyAction">
       <property name="...">...</property>
     </bean>

Note that you can use a single `ContextLoaderPlugIn` for all Struts modules. That context can in turn be loaded from multiple XML files, for example split according to Struts modules. Alternatively, define one `ContextLoaderPlugIn` per Struts module, specifying appropriate "contextConfigLocation" parameters. In both cases, the Spring bean name has to include the module prefix.

If you also need the Tiles setup functionality of the original `TilesRequestProcessor`, use `DelegatingTilesRequestProcessor`. As there is just a single central class to customize in Struts, we have to provide another subclass here, covering both the Tiles and the Spring delegation aspect.

If this `RequestProcessor` conflicts with the need for a different `RequestProcessor` subclass (other than `TilesRequestProcessor`), consider using `DelegatingActionProxy` as the Struts `Action` type in your struts-config file.

The default implementation delegates to the `DelegatingActionUtils` class as much as possible, to reuse as much code as possible despite the need to provide two `RequestProcessor` subclasses. If you need to subclass yet another `RequestProcessor`, take this class as a template, delegating to `DelegatingActionUtils` just like it.

Since:
  1.0.2
Author:
  Juergen Hoeller
See Also:
  `determineActionBeanName(org.apache.struts.action.ActionMapping)`, `DelegatingTilesRequestProcessor`, `DelegatingActionProxy`, `DelegatingActionUtils`, `ContextLoaderPlugIn`

Field Summary

Fields inherited from class org.apache.struts.action.RequestProcessor
`actions, INCLUDE_PATH_INFO, INCLUDE_SERVLET_PATH, log, moduleConfig, servlet`

Constructor Summary
`DelegatingRequestProcessor()`

Method Summary
`protected String` `determineActionBeanName(ActionMapping mapping)` Determine the name of the `Action` bean, to be looked up in the `WebApplicationContext`.
`protected Action` `getDelegateAction(ActionMapping mapping)` Return the delegate `Action` for the given mapping.
`protected WebApplicationContext` `getWebApplicationContext()` Return the `WebApplicationContext` that this processor delegates to.
`void` `init(ActionServlet actionServlet, ModuleConfig moduleConfig)`
`protected WebApplicationContext` `initWebApplicationContext(ActionServlet actionServlet, ModuleConfig moduleConfig)` Fetch ContextLoaderPlugIn's `WebApplicationContext` from the `ServletContext`, falling back to the root `WebApplicationContext`.
`protected Action` `processActionCreate(HttpServletRequest request, HttpServletResponse response, ActionMapping mapping)` Override the base class method to return the delegate action.

Methods inherited from class org.apache.struts.action.RequestProcessor

`destroy, doForward, doInclude, getInternal, getServletContext, internalModuleRelativeForward, internalModuleRelativeInclude, log, log, process, processActionForm, processActionPerform, processCachedMessages, processContent, processException, processForward, processForwardConfig, processInclude, processLocale, processMapping, processMultipart, processNoCache, processPath, processPopulate, processPreprocess, processRoles, processValidate`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### DelegatingRequestProcessor

    public DelegatingRequestProcessor()

Method Detail

### init

    public void init(ActionServlet actionServlet,
                     ModuleConfig moduleConfig)
              throws ServletException

  Overrides:
    `init` in class `RequestProcessor`
  Throws:
    `ServletException`

### initWebApplicationContext

    protected WebApplicationContext initWebApplicationContext(ActionServlet actionServlet,
                                                              ModuleConfig moduleConfig)
                                                       throws IllegalStateException

  Fetch ContextLoaderPlugIn's `WebApplicationContext` from the `ServletContext`, falling back to the root `WebApplicationContext`.

  This context is supposed to contain the Struts `Action` beans to delegate to.

  Parameters:
    `actionServlet` - the associated `ActionServlet`
    `moduleConfig` - the associated `ModuleConfig`
  Returns:
    the `WebApplicationContext`
  Throws:
    `IllegalStateException` - if no `WebApplicationContext` could be found
  See Also:
    `DelegatingActionUtils.findRequiredWebApplicationContext(org.apache.struts.action.ActionServlet, org.apache.struts.config.ModuleConfig)`, `ContextLoaderPlugIn.SERVLET_CONTEXT_PREFIX`

### getWebApplicationContext

    protected final WebApplicationContext getWebApplicationContext()

  Return the `WebApplicationContext` that this processor delegates to.

### processActionCreate

    protected Action processActionCreate(HttpServletRequest request,
                                         HttpServletResponse response,
                                         ActionMapping mapping)
                                  throws IOException

  Override the base class method to return the delegate action.

  Overrides:
    `processActionCreate` in class `RequestProcessor`
  Throws:
    `IOException`
  See Also:
    `getDelegateAction(org.apache.struts.action.ActionMapping)`

### getDelegateAction

    protected Action getDelegateAction(ActionMapping mapping)
                                throws BeansException

  Return the delegate `Action` for the given mapping.

  The default implementation determines a bean name from the given `ActionMapping` and looks up the corresponding bean in the `WebApplicationContext`.

  Parameters:
    `mapping` - the Struts `ActionMapping`
  Returns:
    the delegate `Action`, or `null` if none found
  Throws:
    `BeansException` - if thrown by `WebApplicationContext` methods
  See Also:
    `determineActionBeanName(org.apache.struts.action.ActionMapping)`

### determineActionBeanName

    protected String determineActionBeanName(ActionMapping mapping)

  Determine the name of the `Action` bean, to be looked up in the `WebApplicationContext`.

  The default implementation takes the `mapping path` and prepends the `module prefix`, if any.

  Parameters:
    `mapping` - the Struts `ActionMapping`
  Returns:
    the name of the Action bean
  See Also:
    `DelegatingActionUtils.determineActionBeanName(org.apache.struts.action.ActionMapping)`, `ActionConfig.getPath()`, `ModuleConfig.getPrefix()`

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