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JSP Tag Libraries : Chapter 10: Iterating with Tags

10.7 Summary

Iteration is a crucial task in almost any web application, yet until the arrival of custom JSP tags, it could only be accomplished using scriptlets. As we stated, iteration scriptlets render the JSP code difficult to read and maintain, and even worse, place a premium on the content developer's knowledge of Java. Custom tags fix these problems at a reasonably low price.

We also presented a generic way to develop iteration tags. In fact, the code developed for this chapter can be used in your own daily work (e. g., iteration on something that is not an Array, Enumeration, or Iterator) with a relatively small time investment. Simply extend IterateTag or IterationTagSupport, override a method, and gain full access to the custom tag iteration functionality.

As a last phase in enhancing the quality and ease-of-use of our iteration tags, body content processing was added to the iteration tags to make using the iterator properties easier. This body content processing is by no means unique to iteration tags. In fact, you can implement it in any tags that extend the BodyTag interface and have complete control over their body. Body content processing in this way can speed up the work of the JSP developer, by allowing you to introduce simple, proprietary syntax in your JSPs. It should be considered an appealing alternative to using smaller custom tags, such as the show tags that we developed, especially in cases in which the size of the parsed content is small compared to the size of the entire page.

Next we'll see how we can integrate custom tags with a database to provide simple tag-based access to a database server.

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