Tutorials : Applying Design Patterns to Your Struts Validation Framework:

Applying Design Patterns to Your Struts Validation Framework

by James (Jun B.) You

In today's Web applications, friendly user input validations with obvious graphic alert images and warning messages have become standard. These input validation rules are defined based on business needs, which filter out any bad data input by users. This not only increases system stability, but also improves user experience. How can you add this type of validation to your Web application?

The popular Java Web MVC framework, Apache Struts, provides an ideal solution for validating form input. This article will show you how to use it through solving a practical validation scenario. You'll see two different implementation solutions: the first uses the traditional procedural programming method; the second demonstrates the object-oriented approach by way of Struts customized validation plug-in integration.

Hopefully, this comparison will show you how object-oriented design principles and design patterns-specifically, the strategy, factory, and singleton patterns, can be applied to Struts' customized form validation.

The Various Validation Scenarios

The self-registration form provided by ABC Wireless Inc. needs to validate customers based on their personal identity numbers, which were created when the customer first registered. The personal identity or credential could be one of the following:

ABC PIN (Personal Identity Number)	Social Assistance No.
Driver License	Treaty Status No.
Immigration No. Veteran ID	Health Card No.
Old Age Security No.	Birth Certificate No.
Passport No.
Refugee Claimant No.	.... more and more (might be Credit Card Number)

Each personal identity has its own validation rules: minimum length, maximum length, and data format pattern. Nowadays, you can changed (removed/added/modified) these dynamically. Listing 1 shows detailed validation rules.

How to Add Java Applets to Your Site

New on the Java Boutique:

New Review:

Time Management Made Easy with the Quartz Enterprise Job Scheduler
Why not just use the Java timer API? This open source scheduling API boasts simplicity, ease-of-integration, a well-rounded feature set, and it's free!

New Applet:

Reverse Complement
Reverse Complement is a simple applet that converts DNA or RNA sequences into three useful formats.

Elsewhere on internet.com:

WebDeveloper Java
Lots of Java information on webdeveloper.com

WDVL Java
Thorough Java resource at the Web Developer's Virtual Library.

ScriptSearch Java
Hundreds of free Java code files to download.

jGuru: Your View of the Java Universe
Customizable portal with online training, FAQs, regular news updates, and tutorials.