| An Action helper class 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) in the associated Action 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.
To implement this dispatch behaviour in an Action,
class create your custom Action as follows, along with the methods you require
(and optionally "cancelled" and "unspecified" methods):
public class MyCustomAction extends Action {
protected ActionDispatcher dispatcher = new EventActionDispatcher(this);
public ActionForward execute(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws Exception {
return dispatcher.execute(mapping, form, request, response);
}
}
since:
Struts 1.2.9 | 