用Tiles 开发应用外文文献翻译.doc

Developing applications with Tiles Leveraging layouts Usability is a prime concern in the design of today’s applications—and consistency is a prime ingredient of usability. Users want to stay focused on the task at hand and are easily annoyed by any small inconsistency in an application’s interface or screen layout. Consistency is no small challenge for a dynamic web application; it is commonplace for each page to be coded by hand. Layout tools for static pages are available to most designers today, but few of these are available to applications based on JavaServer Pages. Worse, the look and feel of an application is usually the last detail to be finalized, and then it will often change between versions—or even arbitrarily as part of a greater website “relaunch.” This can create a nightmarish round of last-minute coding and testing—even if only to alter the background color or add a new link to the menu bar. Of course, consistency is more than a hobgoblin; it’s a hallmark of good design. Like any other component, web pages contain many common elements, headers, footers, menus, and so forth. Often, these are cut-and-pasted from one page to the next. But like any component, bugs are found and features are enhanced, leading to another round of cut-and-paste “reuse.” In a web application, page markup is a programming component like any other and should be held to the same standard of reuse. Layering with dynamic templates In the first part of this book, we stressed the importance of layering an application to isolate the effects of change. By compartmentalizing an application, we can change one piece without disrupting the other pieces. The same concept can be applied within the presentation layer to separate the look and feel from the actual content. One approach to separating layout from content is the use of dynamic JSP includes. The JSP specification provides for both static and dynamic includes. The standard JSP action for a dynamic include is jsp:include. We make