java.lang.Object
   org.apache.struts.action.Action
      org.apache.struts.actions.DispatchAction
         org.apache.struts.actions.MappingDispatchAction

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:

• public ActionForward create(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
• public ActionForward edit(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
• public ActionForward save(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
• public ActionForward delete(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
• public ActionForward list(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception

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 ActionForward execute(ActionMapping mapping,
    ActionForm form,
    HttpServletRequest request,
    HttpServletResponse response) throws Exception 
{
        
        // Use the overridden getMethodName. 
        return super.execute(mapping, form, request, response);
}

 protected String getMethodName(ActionMapping mapping,
    ActionForm form,
    HttpServletRequest request,
    HttpServletResponse response,
    String parameter) throws Exception 
{
        
        // Return the unresolved mapping parameter.
        return parameter;
}

 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);
}