Struts%20Interview%20Questions%20and%20Answers

Question: DynaBean and BeanUtils

Answer: Another major complaint usually heard amongst Struts 1.0 users is the extensive effort involved in writing the FormBean (a.k.a. ActionForm) classes.
Struts provides two-way automatic population between HTML forms and Java objects, the FormBeans. To take advantage of this however, you have to write one FormBean per HTML form. (In some use cases, a FormBean can actually be shared between multiple HTML forms. But those are specific cases.) Struts' FormBean standard follows faithfully the verbose JavaBean standard to define and access properties. Besides, to encourage a maintainable architecture, Struts enforces a pattern such that it is very difficult to 'reuse' a model-layer object (e.g. a ValueObject from the EJB tier) as a FormBean. Combining all these factors, a developer has to spend a significant amount of time to write tedious getters/setters for all the FormBean classes.
Struts 1.1 offers an alternative, Dynamic ActionForms, which are based on DynaBeans. Simply put, DynaBeans are type-safe name-value pairs (think HashMaps) but behave like normal JavaBeans with the help of the BeanUtils library. (Both the DynaBeans and the BeanUtils library were found to be useful and generic enough that they have been 'promoted' into Jakarta's Commons project.) With Dynamic ActionForms, instead of coding the tedious setters/getters, developers can declare the required properties in the struts-config.xml files. Struts will instantiate and initialize Dynamic ActionForm objects with the appropriate metadata. From then onwards, The Dynamic ActionForm instance is treated as if it is an ordinary JavaBean by Struts and the BeanUtils library.