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org.apache.struts.actions
public class: MappingDispatchAction [javadoc | source]
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:

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.

Fields inherited from org.apache.struts.actions.DispatchAction:
clazz,  log,  messages,  methods,  types
Method from org.apache.struts.actions.MappingDispatchAction Summary:
execute,   getMethodName,   unspecified
Methods from org.apache.struts.actions.DispatchAction:
cancelled,   dispatchMethod,   execute,   getMethod,   getMethodName,   getParameter,   unspecified
Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from org.apache.struts.actions.MappingDispatchAction Detail:
 public ActionForward execute(ActionMapping mapping,
    ActionForm form,
    HttpServletRequest request,
    HttpServletResponse response) throws Exception 
    Process the specified HTTP request, and create the corresponding HTTP response (or forward to another web component that will create it). Return an ActionForward 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.
 protected String getMethodName(ActionMapping mapping,
    ActionForm form,
    HttpServletRequest request,
    HttpServletResponse response,
    String parameter) throws Exception 
    Returns the method name, given a parameter's value.
 protected ActionForward unspecified(ActionMapping mapping,
    ActionForm form,
    HttpServletRequest request,
    HttpServletResponse response) throws Exception 
    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.