Rajiv's View

Struts

Top Level Struts Packages

Controller Components

Receive a client request,invoke a business operation, coordinate view to return to client
Many struts controller components

org.apache. struts. action. Action
Not abstract
Extension of Controller component
bridge or decoupler-client-user action, business operation
Allows more than One to one action between user action and business action
execute() menthod-
public ActionForward execute(ActionMapping mapping, ActionForm form,HttpRequest req, HttpResponse res) throws Exception

Called by controller upon client request
One instance of each action class in an application
Developer must ensure thread safety of action class
Developer must overide method execute()
Each action class extends Action and overrides method execute().
No try/catch or InvalidLoginException
Struts uses declarative exception handling
Exceptions for actions are specfied in Struts configuration file
Action instances are invoked by the Struts framework from mappings specified in Action Mapping files that use URIs with a path attribute.
Returned View from an Action is specified by ActionForward return object.

Using Data Transfer Objects (DTOs)

Struts View Componets

Framework use of Action Forms for a Request

Check mapping to see if ActionForm is configured
If present, use action name to look up bean configuration
Check if action form created
Reuse if action form is created
Otherwise create new instance, store in appropriate scope as specified in action element.
Call reset()
Iterate request parameters , populate every param with Action form with action parameter
If validate is 'true' invoke validate.
Two important methods of Action form: reset() and validate()
reset() called by controller before populating ActionForm with request values.
Action form can reset its values back to default state.
Probably not to be used with multiple pages as values are not reset until an instance is destroyed.
Validate called after request values are inserted into ActionForm.
Must not be used for business operations- These are done in business objects only.
Validation is used for Presentation Validation only.
All ActionForms of application configued in form-beans section on Config File.

Search