An abstract Action that dispatches to a public
* method that is named by the parameter attribute of
* the corresponding ActionMapping. This is useful for developers who prefer
* to combine many related actions into a single Action class.
To configure the use of this action in your
* struts-config.xml file, create an entry like this:
* <action path="/saveSubscription"
* type="org.example.SubscriptionAction"
* name="subscriptionForm"
* scope="request"
* input="/subscription.jsp"
* parameter="method"/>
* where 'method' is the name of a method in your subclass of * MappingDispatchAction that has the same signature (other than method * name) of the standard Action.execute method. For example, you might combine * the methods for managing a subscription into a single * MappingDispatchAction class using the following methods:
*for which you would create corresponding <action> configurations * that reference this class:
* *
* <action path="/createSubscription"
* type="org.example.SubscriptionAction"
* parameter="create">
* <forward name="success" path="/editSubscription.jsp"/>
* </action>
*
* <action path="/editSubscription"
* type="org.example.SubscriptionAction"
* parameter="edit">
* <forward name="success" path="/editSubscription.jsp"/>
* </action>
*
* <action path="/saveSubscription"
* type="org.example.SubscriptionAction"
* parameter="save"
* name="subscriptionForm"
* validate="true"
* input="/editSubscription.jsp"
* scope="request">
* <forward name="success" path="/savedSubscription.jsp"/>
* </action>
*
* <action path="/deleteSubscription"
* type="org.example.SubscriptionAction"
* name="subscriptionForm"
* scope="request"
* input="/subscription.jsp"
* parameter="delete">
* <forward name="success" path="/deletedSubscription.jsp"/>
* </action>
*
* <action path="/listSubscriptions"
* type="org.example.SubscriptionAction"
* parameter="list">
* <forward name="success" path="/subscriptionList.jsp"/>
* </action>
* NOTE - Unlike DispatchAction, mapping characteristics * may differ between the various handlers, so you can combine actions in the * same class that, for example, differ in their use of forms or validation. * Also, a request parameter, which would be visible to the application user, * is not required to enable selection of the handler method. *
* * @version $Rev: 54929 $ $Date: 2004-10-16 17:38:42 +0100 (Sat, 16 Oct 2004) $ * @since Struts 1.2 */ public class MappingDispatchAction extends DispatchAction { // -------------------------------------------------------- Class Variables /** * Commons Logging instance. */ private static Log log = LogFactory.getLog(MappingDispatchAction.class); // --------------------------------------------------------- Public Methods /** * Process the specified HTTP request, and create the corresponding HTTP * response (or forward to another web component that will create it). * Return anActionForward instance describing where and how
* control should be forwarded, or null if the response has
* already been completed.
*
* This method dispatches the request to other methods of
* MappingDispatchAction using the 'parameter' attribute of
* ActionMapping and Java Introspection.
*
* @param mapping The ActionMapping used to select this instance
* @param form The optional ActionForm bean for this request (if any)
* @param request The HTTP request we are processing
* @param response The HTTP response we are creating
*
* @return Return an ActionForward instance describing where
* and how control should be forwarded, or null if
* the response has already been completed.
*
* @exception Exception if an exception occurs
*/
public ActionForward execute(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws Exception {
// Use the overridden getMethodName.
return super.execute(mapping, form, request, response);
}
/**
* Method which is dispatched to when there is no value for the
* parameter in the ActionMapping. Subclasses of
* MappingDispatchAction should override this method
* if they wish to provide default behavior different than throwing a
* ServletException.
*
* @param mapping The ActionMapping used to select this instance
* @param form The optional ActionForm bean for this request (if any)
* @param request The HTTP request we are processing
* @param response The HTTP response we are creating
*
* @return Return an ActionForward instance describing where
* and how control should be forwarded, or null if
* the response has already been completed.
*
* @exception Exception if an exception occurs
*/
protected ActionForward unspecified(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws Exception {
String message =
messages.getMessage("mapping.parameter", mapping.getPath());
log.error(message);
throw new ServletException(message);
}
/**
* Returns the method name, given a parameter's value.
*
* @param mapping The ActionMapping used to select this instance
* @param form The optional ActionForm bean for this request (if any)
* @param request The HTTP request we are processing
* @param response The HTTP response we are creating
* @param parameter The ActionMapping parameter's name
*
* @return The method's name.
* @since Struts 1.2.0
*/
protected String getMethodName(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response,
String parameter)
throws Exception {
// Return the unresolved mapping parameter.
return parameter;
}
}