Java Enterprise Best Practices

Choosing Between Beans and Custom Actions

Beans and custom actions (packaged in a tag library) are regular Java classes that just happen to adhere to a few rules. This means they can do anything that any Java class can do. Whether it’s best to implement application functionality as an action or a bean might not always be clear. My rule of thumb is that a bean is a great carrier of information, and a custom action is great for processing information.

A bean is a perfect vehicle for making information gathered or created in a servlet available to a JSP page. The standard <jsp:getProperty> action and the JSTL EL make it easy to access single-value bean properties, and the JSTL <c:forEach> action allows you to iterate through a multivalue property such as an array, a List, or a Map.

A bean can implement methods other than the property accessors to encapsulate functionality intended for use in many different environments, such as applets, servlets, and JSP pages. Calling such a method in a JSP page, however, requires scripting code and should be avoided. A custom action that internally uses the bean is a better choice. The custom action acts as a JSP-specific adapter for the bean to make it easier for a page author to use.

With the introduction of JSTL, the need for custom actions is significantly lower than it used to be, but occasionally, they are still needed. Examples include custom actions for conditional tests not covered by JSTL (e.g., testing if an authenticated user belongs ...