Java Doc for ActionForm.java in  » Web-Framework » struts-1.3.8 » org » apache » struts » action » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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.

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.

Return the controller servlet instance to which we are attached.

>Can be used to reset all bean properties to their default state.

Can be used to reset bean properties to their default state, as needed.

Can be used to 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.

Can be used to 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.

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/form-data".

Return the servlet instance to which we are attached.

Return the controller servlet instance to which we are attached. as an ActionServletWrapper.

>Can be used to 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.

Can be used to 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.

Set the Handler provided for use in dealing with file uploads.

Set the servlet instance to which we are attached (if servlet is non-null).

Can be used to 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.

Can be used to 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.