The last of the MVC components to discuss are the view components. Arguably, they are the easiest to understand. The view components typically employed in a Struts application are:
Data transfer objects
Java resource bundles
ActionForm objects are used in the
framework to pass client input data back and forth between the user
and the business layer. The framework automatically collects the
input from the request and passes this data to an
Action using a form bean, which then can be passed
along to the business layer. To keep the presentation layer decoupled
from the business layer, you should not pass the
ActionForm itself to the business layer; rather,
create the appropriate DTO using the data from the
ActionForm. The following steps illustrate how the
framework processes an
ActionForm for every request:
Check the mapping for the action and see if an
ActionForm has been configured.
ActionForm is configured for the action, use
name attribute from the
action element to look up the form bean
Check to see if an instance of the
already has been created.
ActionForm instance is present in the
appropriate scope and it’s the same type as needed
for the new request, reuse it.
Otherwise, create a new instance of the required
ActionForm and store it in the appropriate scope
(set by the
scope attribute for the
Call the ...