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EJB 3 Developer Guide

EJB 3 Developer Guide

By : Michael Sikora
4.2 (6)
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EJB 3 Developer Guide

EJB 3 Developer Guide

4.2 (6)
By: Michael Sikora

Overview of this book

Table of Contents (18 chapters)
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EJB 3 Developer Guide
Credits
About the Author
About the Reviewers
Preface
1
Annotations and Their Corresponding Packages

O/R Mapping Additional Annotations


We will modify our application again and introduce some more object-relational mapping annotations. Specifically we will cover the @Embedded, @Embeddable, @Enumerated, and @MapKey annotations.

First we decide to embed the Referee entity within the Customer entity. An embedded Referee entity shares the identity of the owning Customer entity. A Referee entity cannot exist on its own without a corresponding Customer entity. Such a Referee entity cannot be independently persisted, it is persisted by default whenever the owning Customer entity is persisted. However, we still map a Referee object onto a relational database in the usual manner.

We also decide to add an enumerated type, gender, as a Customer attribute.

To indicate an entity is embedded EJB 3 provides two annotations: @Embedded and @Embeddable. @Embedded is used within the owning entity and @Embeddable within the embedded entity. Below is the modified version of the Customer entity:

@Entity
public...
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EJB 3 Developer Guide
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