Java Data Objects

Project Build Environment

In this section, we examine a development environment to compile and run our JDO application. This includes the project directory structure, the jar files necessary to build applications, and the syntax for enhancing persistent classes. We describe class enhancement later in this section. The environment setup partly depends on which JDO implementation you use. Your specific project’s development environment and directory structure may differ.

You can use either the Sun JDO reference implementation or another implementation of your choosing. The examples in this book use the JDO reference implementation. You can download the JDO reference implementation by visiting http://www.jcp.org and selecting JSR-12. Once you have installed a JDO implementation, you will need to establish a project directory structure and define a classpath that includes all the directories and jar files necessary to build and run your application.

JDO introduces a new step in your build process, called class enhancement. Each persistent class must be enhanced so that it can be used in a JDO runtime environment. Your persistent classes are compiled using a Java compiler that produces a class file. An enhancer program reads these class files and JDO metadata and creates new class files that have been enhanced to operate in a JDO environment. Your JDO application should load these enhanced class files. The JDO reference implementation includes an enhancer called the reference enhancer ...