Using CASTOR for DB Access from STRUTS
Objective:
In this article we
will look at CASTOR JDO, a data access or Object to relational
(‘OR’) mapping framework and how it improves the data access
code. Our goals should be:
- Improve the data access code written in the last article using JDBC
- Discuss how to use CASTOR with the STRUTS application.
- Demo use of a mapping tool to generate the mapping file for CASTOR.
- Finally quickly refer to some of the potential limitations of CASTOR as discussed on some other website and discuss possible solutions
For a very good introduction to CASTOR and some details about
its capabilities please read:
Mapping Java Objects to a Database with Castor-JDO: by
Keld H. Hansen, and keep an eye on his next article for
additional CASTOR features. Lets get started.
Pre-requisite:
Before starting this you should have read the part 1 and
part2. As a starting point for this article, we will
use the completed code from part 2 from The Open Stack website look for
the Part 2 ZIP file.
Quick Overview:
In part 1 and 2 we built a simple web application with STRUTS
and we added a database access code--directly using JDBC. The
JDBC code was useful for learning the basics of DB access from
STRUTS and looking at how we create the data source using
STRUTS, but for a real life application writing JDBC code may
not be the best idea. Specifically as it includes the table name
and column names as part of the code.
Preparation:
- You will need to download the starting STRUTS code from The Open Stack website, look for
the Part 2 ZIP file. You should also have a database and create
the sample table as described in part 2. You will need a JDBC
driver for your database. Refer to Part 2 for instruction on
setting up MySQL database, creating and populating the sample
table and setting up the JDBC driver. We will use the sample
EMPLOYEE table that has these three fields: shortname CHAR(5),
firstname VARCHAR(25), lastname VARCHAR (30). In part 2, we have
provided a sample SQL file ,‘emp.sql’ to create the table in
MySQL and add some test data.
- Download and install CASTOR-–basically this is as simple as
downloading the CASTOR zip/tar from Castor web
site and extracting the following two jar files: castor-
0.9.4.2.jar and xercesImpl.jar. Add these 2 jars under the WEB-
INF/lib directory of the sample web application.
OK! Now we are ready to change our web application for database
access!
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.
| 
