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 concepts


Mapping objects to relations is the core mission of Hibernate, and as we discussed previously, this can be a difficult challenge that can only be overcome by understanding the fundamental concepts.

Let's explore mapping concepts by reviewing some of the fundamentals of relational databases, such as relational algebra, simple and composite IDs, join tables, and foreign keys.

Instances and rows

The origin of relational database concepts is Relational Algebra, which is based on Set Theory. Just as we think of objects as instances of classes, you should also think of a database row (a tuple) as an element of a set (the relation) that is defined by the database tab.

For example, if your object graph contains an instance of the Person entity class that represents John and another instance that represents Sara, you should think of these as two rows in the Person table.

In both cases, by being an instance of a class or a row of a table, they agree to possess certain attributes, such...