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)

Enumeration and custom data type


In this section, we see how to map "constants" to enumerated types. Constants are considered a small finite set of data elements, such as gender (Male, Female) or days of the week, such as Monday, Tuesday, and so on. Hibernate supports using enumerated types for mapping database columns containing data in a finite closed set. (The definition of a closed set comes straight from set theory.)

If you don't wish to use enumerated types, you can create a custom data type to map your data to a primitive type in Java, and you'll see that after we discuss the enumerated type.

Enumerated type

You can define an enumeration in Java and let Hibernate handle the mapping of "constants". JPA supports two kinds of enum: ORDINAL and STRING. If you use the ORDINAL enumeration type, the data in the mapped column is assumed to be an integer. You can guess how the STRING enumeration type behaves:

public enum WeekDay {
  Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday...