tutorials : Using CASTOR for DB Access from STRUTS :

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!

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