org.apache.struts.action
public abstract class ActionForm extends Object implements Serializable
An ActionForm is a JavaBean optionally associated with
one or more ActionMappings
. Such a bean will have had its
properties initialized from the corresponding request parameters before
the corresponding Action.execute
method is called.
When the properties of this bean have been populated, but before the
execute
method of the Action
is called, this bean's
validate
method will be called, which gives the bean a chance
to verify that the properties submitted by the user are correct and valid.
If this method finds problems, it returns an error messages object that
encapsulates those problems, and the controller servlet will return control
to the corresponding input form. Otherwise, the validate
method returns null
, indicating that everything is acceptable
and the corresponding Action.execute
method should be
called.
This class must be subclassed in order to be instantiated. Subclasses should provide property getter and setter methods for all of the bean properties they wish to expose, plus override any of the public or protected methods for which they wish to provide modified functionality.
Because ActionForms are JavaBeans, subclasses should also implement
Serializable
, as required by the JavaBean specification.
Some containers require that an object meet all JavaBean requirements
in order to use the introspection API upon which ActionForms rely.
Version: $Rev: 54929 $ $Date: 2004-10-16 17:38:42 +0100 (Sat, 16 Oct 2004) $
Field Summary | |
---|---|
protected MultipartRequestHandler | multipartRequestHandler The MultipartRequestHandler for this form, can be
|
protected ActionServlet | servlet The servlet instance to which we are attached. |
Method Summary | |
---|---|
MultipartRequestHandler | getMultipartRequestHandler() Return the |
protected ActionServlet | getServlet() Return the servlet instance to which we are attached. |
ActionServletWrapper | getServletWrapper() Return the controller servlet instance to which we are attached.
as an |
void | reset(ActionMapping mapping, ServletRequest request) Reset all bean properties to their default state. |
void | reset(ActionMapping mapping, HttpServletRequest request) Reset bean properties to their default state, as needed. |
void | setMultipartRequestHandler(MultipartRequestHandler multipartRequestHandler) Set the Handler provides to use in dealing with file uploads. |
void | setServlet(ActionServlet servlet) Set the servlet instance to which we are attached (if
|
ActionErrors | validate(ActionMapping mapping, ServletRequest request) Validate the properties that have been set for this non-HTTP request,
and return an |
ActionErrors | validate(ActionMapping mapping, HttpServletRequest request) Validate the properties that have been set for this HTTP request,
and return an |
The MultipartRequestHandler for this form, can be
null
.
The servlet instance to which we are attached.
Return the MultipartRequestHandler
for this form
The reasoning behind this is to give form bean developers
control over the lifecycle of their multipart requests
through the use of the finish
and/or rollback
methods of MultipartRequestHandler
. This method will return
null
if this form's enctype is not
"multipart/request-data".
See Also: MultipartRequestHandler
Return the servlet instance to which we are attached.
Return the controller servlet instance to which we are attached.
as an ActionServletWrapper
.
Since: Struts 1.0.1
See Also: ActionServletWrapper
Reset all bean properties to their default state. This method is called before the properties are repopulated by the controller.
The default implementation attempts to forward to the HTTP version of this method.
Parameters: mapping The mapping used to select this instance request The servlet request we are processing
Reset bean properties to their default state, as needed. This method is called before the properties are repopulated by the controller.
The default implementation does nothing. In practice, the only properties that need to be reset are those which represent checkboxes on a session-scoped form. Otherwise, properties can be given initial values where the field is declared.
If the form is stored in session-scope so that values can be collected over multiple requests (a "wizard"), you must be very careful of which properties, if any, are reset. As mentioned, session-scope checkboxes must be reset to false for any page where this property is set. This is because the client does not submit a checkbox value when it is clear (false). If a session-scoped checkbox is not proactively reset, it can never be set to false.
This method is not the appropriate place to initialize form value for an "update" type page (this should be done in a setup Action). You mainly need to worry about setting checkbox values to false; most of the time you can leave this method unimplemented.
Parameters: mapping The mapping used to select this instance request The servlet request we are processing
Set the Handler provides to use in dealing with file uploads.
Parameters: multipartRequestHandler The Handler to use for fileuploads.
Set the servlet instance to which we are attached (if
servlet
is non-null), or release any allocated resources
(if servlet
is null).
Parameters: servlet The new controller servlet, if any
Validate the properties that have been set for this non-HTTP request,
and return an ActionErrors
object that encapsulates any
validation errors that have been found. If no errors are found, return
null
or an ActionErrors
object with no
recorded error messages.
The default implementation attempts to forward to the HTTP version of this method.
Parameters: mapping The mapping used to select this instance request The servlet request we are processing
Validate the properties that have been set for this HTTP request,
and return an ActionErrors
object that encapsulates any
validation errors that have been found. If no errors are found,
return null
or an ActionErrors
object with
no recorded error messages.
The default implementation performs no validation and returns
null
. Subclasses must override this method to provide
any validation they wish to perform.
Parameters: mapping The mapping used to select this instance request The servlet request we are processing