FormView is JSP taglib to manage postrender of JSP (HTML render)according to state (CREATE, READ, UPDATE,...).
With Formview you develop just ONE JSP to manage READ-ONLY and READ-WRITE form. For instance, on CREATE state HTML inputs will be READ-WRITE and on READ state inputs will be READ-ONLY. You can use FormView with HTML or any JSP taglib (struts, struts-layout, jsp...) that you want postrender by FormView.
With FormView you can customize render of input according to state (add attribute readonly to HTML input or
replace it by value when form must be displayed to READ state). Formview can be plugged with Struts Validator to use information about
validation to update HTML according to validation
(eg : add maxlength attribute to HTML input if form must be validate by maxlength, add calendar if input must be date).