Book Image

Mastering Hibernate

By : Ramin Rad, Koushik Srinivas Kothagal
Book Image

Mastering Hibernate

By: Ramin Rad, Koushik Srinivas Kothagal

Overview of this book

Hibernate has been so successful since its inception that it even influenced the Java Enterprise Edition specification in that the Java Persistence API was dramatically changed to do it the Hibernate way. Hibernate is the tool that solves the complex problem of Object Relational Mapping. It can be used in both Java Enterprise applications as well as .Net applications. Additionally, it can be used for both SQL and NoSQL data stores. Some developers learn the basics of Hibernate and hit the ground quickly. But when demands go beyond the basics, they take a reactive approach instead of learning the fundamentals and core concepts. However, the secret to success for any good developer is knowing and understanding the tools at your disposal. It’s time to learn about your tool to use it better This book first explores the internals of Hibernate by discussing what occurs inside a Hibernate session and how Entities are managed. Then, we cover core topics such as mapping, querying, caching, and we demonstrate how to use a wide range of very useful annotations. Additionally, you will learn how to create event listeners or interceptors utilizing the improved architecture in the latest version of Hibernate.
Table of Contents (16 chapters)

Mapping and association

In the previous chapter, we demonstrated many annotations that defined mapping and associations between objects; most of those are JPA annotations. In this section, we will look at more annotations that affect mapping and associations. Most of these are only available in Hibernate, but we also cover some very useful JPA annotations that you may not have used.

@Any and @ManyToAny

The @Any and @ManyToAny annotations are only available in Hibernate. They are defined to support polymorphism in Java, in the sense that a discriminator column determines the subclass of a parent class (or interface).

For instance, if you have a table with a discriminator column that helps distinguish one class from the other, you can use the @Any annotation to map the rows to the correct class. We will discuss @ManyToAny here, as @Any is well documented in Hibernate API JavaDoc, but in short, @Any is used for a one-to-one association.

Consider the following relations that keep track of a person...