org.apache.struts.actions
Class EventDispatchAction

java.lang.Object
  org.apache.struts.action.Action
      org.apache.struts.actions.BaseAction
          org.apache.struts.actions.DispatchAction
              org.apache.struts.actions.EventDispatchAction

public class EventDispatchAction
extends DispatchAction

An Action that dispatches to to one of the public methods that are named in the parameter attribute of the corresponding ActionMapping and matches a submission parameter. This is useful for developers who prefer to use many submit buttons, images, or submit links on a single form and whose related actions exist in a single Action class.

The method(s) must have the same signature (other than method name) of the standard Action.execute method.

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="save,back,recalc=recalculate,default=save"/>
 

where parameter contains three possible methods and one default method if nothing matches (such as the user pressing the enter key).

For utility purposes, you can use the key=value notation to alias methods so that they are exposed as different form element names, in the event of a naming conflict or otherwise. In this example, the recalc button (via a request parameter) will invoke the recalculate method. The security-minded person may find this feature valuable to obfuscate and not expose the methods.

The default key is purely optional. If this is not specified and no parameters match the list of method keys, null is returned which means the unspecified method will be invoked.

The order of the parameters are guaranteed to be iterated in the order specified. If multiple buttons were accidently submitted, the first match in the list will be dispatched.

Since:

Struts 1.2.9

Field Summary

Fields inherited from class org.apache.struts.actions.DispatchAction

clazz, log, methods, types

Fields inherited from class org.apache.struts.actions.BaseAction

messages

Fields inherited from class org.apache.struts.action.Action

servlet

Constructor Summary

EventDispatchAction()

Method Summary

protected java.lang.String	getMethodName(ActionMapping mapping, ActionForm form, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, java.lang.String parameter) Returns the method name, given a parameter's value.
protected ActionForward	unspecified(ActionMapping mapping, ActionForm form, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Method which is dispatched to when there is no value for specified request parameter included in the request.

Methods inherited from class org.apache.struts.actions.DispatchAction

cancelled, dispatchMethod, execute, getMethod, getParameter

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

addErrors, addMessages, execute, generateToken, getErrors, getLocale, getMessages, getResources, getResources, getServlet, isCancelled, isTokenValid, isTokenValid, resetToken, saveErrors, saveErrors, saveMessages, saveMessages, saveToken, setLocale, setServlet

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

EventDispatchAction

public EventDispatchAction()

Method Detail

unspecified

protected ActionForward unspecified(ActionMapping mapping,
                                    ActionForm form,
                                    javax.servlet.http.HttpServletRequest request,
                                    javax.servlet.http.HttpServletResponse response)
                             throws java.lang.Exception

Method which is dispatched to when there is no value for specified request parameter included in the request. Subclasses of DispatchAction should override this method if they wish to provide default behavior different than throwing a ServletException.

Overrides:

unspecified in class DispatchAction

Parameters:

mapping - The ActionMapping used to select this instance

form - The optional ActionForm bean for this request (if any)

request - The non-HTTP request we are processing

response - The non-HTTP response we are creating

Returns:

The forward to which control should be transferred, or null if the response has been completed.

Throws:

java.lang.Exception - if the application business logic throws an exception.

getMethodName

protected java.lang.String getMethodName(ActionMapping mapping,
                                         ActionForm form,
                                         javax.servlet.http.HttpServletRequest request,
                                         javax.servlet.http.HttpServletResponse response,
                                         java.lang.String parameter)
                                  throws java.lang.Exception

Returns the method name, given a parameter's value.

Overrides:

getMethodName in class DispatchAction

Parameters:

mapping - The ActionMapping used to select this instance

form - The optional ActionForm bean for this request (if any)

request - The HTTP request we are processing

response - The HTTP response we are creating

parameter - The ActionMapping parameter's name

Returns:

The method's name.

Throws:

java.lang.Exception - if an error occurs.