tutorials : Using CASTOR for DB Access from STRUTS :

Using JDOMapper tool to generate the CASTOR mapping file

We have defined the java class EmpBean.java already as part of part 2. Here are the steps to generate the mapping file for that:

• Download JDOMapper from Source Forge Web site.
• Extract the zip/tar and open jdomapper.bat (or jdomapper.sh). Add the path to your web-inf/classes directory (where you have the EmpBean.class). I added: "D:/STRUTS/Part3/StrutsNetBeansSampleP3/WEB-INF/classes/"
• run this batch file (or the shell script). It will open the GUI interface.
• Refer to the screen shot at the JDOMapper web site.
• Add your class by clicking on project—add class (You can remove the existing default classes by clicking on the delete button at top)
• Give your complete class name such as "com.openstack.struts.testapp.EmpBean"
• It will add the class to the left pane. You can double click on the class name to add information such as the database table it belongs to. Similarly at every filed level you can specify the column name and data type. You can leave the rest of the options to default for now.
• Click on the preview mapping button at the top. It will generate the mapping file. Save it as mapping.xml under your classes directory (where you stored the database.xml file).

Here is how my mapping file looks:

<?xml version="1.0" encoding="UTF-8"?>
<mapping>
  <class auto-complete="false"

name="com.openstack.struts.testapp.EmpBean" access="shared">
   <description>Default mapping for class

com.openstack.struts.testapp.EmpBean</description>
    <map-to table="employee" xml="emp-bean"/>
    <field required="false" transient="false" direct="false"

name="shortname" type="string" lazy="false">
    <sql name="shortname" dirty="check" type="char"

read-only="false"/>
    <bind-xml node="element" name="shortname"/>
    </field>
    <field required="false" transient="false" direct="false"

name="lastname" type="string" lazy="false">
    <sql name="lastname" dirty="check" type="char" 

read-only="false"/>
    <bind-xml node="element" name="lastname"/>
    </field>
    <field required="false" transient="false" direct="false"

name="firstname" type="string" lazy="false">
    <sql name="firstname" dirty="check" type="char" 

read-only="false"/>
    <bind-xml node="element" name="firstname"/>
    </field>
    </class>
</mapping> 

Things to consider when using CASTOR with STRUTS

In this article we invoked Castor JDO calls directly from the STRUTS Action class. While one starts thinking about extracting the "common" parts into a separate class, an important point to consider is thread-safety. Because by its very nature a J2EE web application will have concurrent access from multiple client requests. Here I want to demonstrate one easy solution. Please look at the files CastorJDOFactory.java and TestActionHandler.java here.

If you plan to use JNDI and underlying app server for locating the data source; refer to the Castor website for an example on "PostgreSQL 7.3, JNDI and Tomcat".

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