Introducing Spring Framework

Chapter 9
Adding Persistence to Your
Spring Application
In this chapter, you are going to add some persistence to your My Documents application. So far you have been using
bean definitions and some hard-coded logic to retrieve information about the documents and types of documents.
For testing purposes, hard-coded data is fine, but in a real-world application like the My Documents Spring
application, you need some other mechanisms to retrieve all the information because the data can grow and it will be
a hard to keep putting the data in like that.
The Spring Framework supports a persistence mechanisms using JDBC (Java Database Connectivity) to query,
update, insert, and delete data from databases.
In the My Documents Spring application you are going to use a small footprint database engine called the
HSQLDB engine. This engine allows you to run the database in memory. The idea behind using this HSQLDB
database engine is to avoid spending time setting up a database server and trying to configure it, but later in this
chapter you will see how to use different engines such as MySQL (which is one of the most commonly used databases
engines by the open source community).
But enough talk! Let’s see how to add some persistence to your My Documents Spring application.
Adding Persistence
First, you are going to modify the Model classes and establish the relationship that you have been adding since the
beginning. Figure 9-1 shows this relationship.
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