Pro JPA 2: Mastering the Java (TM) Persistence API

538 Pages·2009·5.54 MB·English

by  Michael Keith

CYAN  YELLOW
 MAGENTA  BLACK
 PANTONE 123 C

BOOKS FOR PROFESSIONALS BY PROFESSIONALS® THE EXPERT’S VOICE® IN JAVA™ TECHNOLOGY
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eBook Available
Pro JPA 2: Mastering the Java™ Java™ EE 6
Pro compliant
Persistence API
J
Dear Reader,
Pro
It’s hard to believe that over 3 years have gone by since the initial 1.0 release of
the Java™ Persistence API. In that time we have seen it go from fledgling API P
to mainstream persistence standard. Along the way, many of you cut your JPA
teeth using the first edition of this book, and we’re happy we were there to help!
JPA 2.0 includes a host of new features, such as additional object-relational A JPA 2
mappings, more object modeling flexibility, typed queries, and a brand-new
criteria API, to name a few. With so much to talk about, we were excited to
update the book and explain all the new features, but we also included some
hints and tips to help you use the API in practice.
If you already have experience with JPA 1.0 then you should benefit from
2
the version tips that point out when a feature was added in 2.0. These tips
were also designed to help users who are writing to a JPA 1.0 implementation,
and are not yet able to make use of the 2.0 features.
Those of you that are new to JPA can rest assured that you were not for-
Authors of
gotten. We have remained true to our original intent to take someone from
Pro EJB™ 3: Java™ having no JPA knowledge all the way to being an advanced JPA’er. You should
Persistence API
be able to quickly learn in the first two chapters what you need to know to get
started. (Veteran JPA programmers might want to start at Chapter 3!) Finally,
Mastering the Java Persistence API
we want to thank you for making the previous edition of this book such a suc- ™
cess. We are pleased that it has become the primary resource for JPA develop-
ers, and hope that you will find this edition equally valuable.
Mike Keith, JPA 2.0 Expert Group Member, and Merrick Schincariol
Create robust, data-driven applications with
Companion eBook
ES this definitive guide to the new JPA 2
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Mike Keith and Merrick Schincariol
SOURCE CODE ONLINE in
www.apress.com ISBN 978-1-4302-1956-9 cK
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54999 rioeit Foreword by Linda DeMichiel, JPA Specification Lead
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Pro JPA 2
Mastering the Java™ Persistence API

■ ■ ■
Mike Keith and
Merrick Schnicariol

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Pro JPA 2
Copyright © 2009 by Mike Keith and Merrick Schincariol
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ISBN-13 (pbk): 978-1-4302-1956-9
ISBN-13 (electronic): 978-1-4302-1957-6
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To the memory of my father, who selflessly offered all that he had, and to my wife Darleen who has
devoted her life to helping children.—Mike

To Anthony, whose boundless creativity continues to inspire me. To Evan, whose boisterous enthusiasm
motivates me to take on new challenges. To Kate, who proves that size is no object when you have the
right attitude. I love you all.—Merrick

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Contents at a Glance

■Contents at a Glance............................................................................................iv(cid:1)
■Contents................................................................................................................v(cid:1)
■Foreword.............................................................................................................xx(cid:1)
■About the Author................................................................................................xxi(cid:1)
■About the Technical Reviewer...........................................................................xxii(cid:1)
■Acknowledgments............................................................................................xxiii(cid:1)
■Preface...............................................................................................................xiv(cid:1)
■Chapter 1: Introduction.........................................................................................1(cid:1)
■Chapter 2: Getting Started...................................................................................17(cid:1)
■Chapter 3: Enterprise Applications.....................................................................33(cid:1)
■Chapter 4: Object-Relational Mapping................................................................69(cid:1)
■Chapter 5: Collection Mapping..........................................................................107(cid:1)
■Chapter 6: Entity Manager................................................................................131(cid:1)
■Chapter 7: Using Queries...................................................................................179(cid:1)
■Chapter 8: Query Language...............................................................................207(cid:1)
■Chapter 9: Criteria API......................................................................................239(cid:1)
■Chapter 10: Advanced Object-Relational Mapping............................................273(cid:1)
■Chapter 11: Advanced Topics............................................................................315(cid:1)
■Chapter 12: XML Mapping Files........................................................................371(cid:1)
■Chapter 13: Packaging and Deployment...........................................................407(cid:1)
■Chapter 14: Testing...........................................................................................429(cid:1)
■Chapter 15: Migration.......................................................................................457
■Index.................................................................................................................481
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Contents

■Contents at a Glance............................................................................................iv(cid:1)
■Contents................................................................................................................v(cid:1)
■Foreword.............................................................................................................xx
■About the Author................................................................................................xxi
■About the Technical Reviewer...........................................................................xxii(cid:1)
■Acknowledgments............................................................................................xxiii(cid:1)
■Preface.............................................................................................................xxiv

■Chapter 1: Introduction.........................................................................................1(cid:1)
Object-Relational Mapping.............................................................................................2(cid:1)
The Impedance Mismatch......................................................................................................................3(cid:1)
Class Representation........................................................................................................................3(cid:1)
Relationships....................................................................................................................................5(cid:1)
Inheritance........................................................................................................................................7(cid:1)
Java Support for Persistence..........................................................................................9(cid:1)
Proprietary Solutions..............................................................................................................................9(cid:1)
JDBC......................................................................................................................................................9(cid:1)
Enterprise JavaBeans..........................................................................................................................10(cid:1)
Java Data Objects................................................................................................................................10(cid:1)
Why Another Standard?................................................................................................11(cid:1)
The Java Persistence API..............................................................................................12(cid:1)
History of the Specification..................................................................................................................12(cid:1)
EJB 3.0 and JPA 1.0........................................................................................................................12(cid:1)
JPA 2.0............................................................................................................................................13(cid:1)
JPA and You....................................................................................................................................13(cid:1)
Overview..............................................................................................................................................13(cid:1)
POJO Persistence............................................................................................................................13(cid:1)
Nonintrusiveness............................................................................................................................14(cid:1)
Object Queries.................................................................................................................................14(cid:1)
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■ CONTENTS
Mobile Entities................................................................................................................................14(cid:1)
Simple Configuration.......................................................................................................................15(cid:1)
Integration and Testability..............................................................................................................15(cid:1)
Summary.......................................................................................................................15(cid:1)
■Chapter 2: Getting Started...................................................................................17(cid:1)
Entity Overview.............................................................................................................17(cid:1)
Persistability........................................................................................................................................17(cid:1)
Identity.................................................................................................................................................18(cid:1)
Transactionality....................................................................................................................................18(cid:1)
Granularity...........................................................................................................................................18(cid:1)
Entity Metadata.............................................................................................................19(cid:1)
Annotations..........................................................................................................................................19(cid:1)
XML......................................................................................................................................................19(cid:1)
Configuration by Exception..................................................................................................................19(cid:1)
Creating an Entity..........................................................................................................20(cid:1)
Entity Manager..............................................................................................................22(cid:1)
Obtaining an Entity Manager................................................................................................................23(cid:1)
Persisting an Entity..............................................................................................................................24(cid:1)
Finding an Entity..................................................................................................................................24(cid:1)
Removing an Entity..............................................................................................................................25(cid:1)
Updating an Entity................................................................................................................................26(cid:1)
Transactions........................................................................................................................................26(cid:1)
Queries.................................................................................................................................................27(cid:1)
Putting It All Together...................................................................................................28(cid:1)
Packaging It Up.............................................................................................................30(cid:1)
Persistence Unit...................................................................................................................................30(cid:1)
Persistence Archive.............................................................................................................................31(cid:1)
Summary.......................................................................................................................32(cid:1)
■Chapter 3: Enterprise Applications.....................................................................33(cid:1)
Application Component Models....................................................................................33(cid:1)
Session Beans...............................................................................................................34(cid:1)
Stateless Session Beans......................................................................................................................35(cid:1)
Defining a Stateless Session Bean.................................................................................................35(cid:1)
Lifecycle Callbacks.........................................................................................................................37(cid:1)
Remote Business Interfaces...........................................................................................................38(cid:1)
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■ CONTENTS
Stateful Session Beans........................................................................................................................39(cid:1)
Defining a Stateful Session Bean....................................................................................................39(cid:1)
Lifecycle Callbacks.........................................................................................................................40(cid:1)
Singleton Session Beans......................................................................................................................42(cid:1)
Defining a Singleton Session Bean.................................................................................................42(cid:1)
Lifecycle Callbacks.........................................................................................................................43(cid:1)
Singleton Concurrency....................................................................................................................43(cid:1)
Message-Driven Beans.................................................................................................45(cid:1)
Defining a Message-Driven Bean.........................................................................................................45(cid:1)
Servlets.........................................................................................................................46(cid:1)
Dependency Management............................................................................................47(cid:1)
Dependency Lookup.............................................................................................................................47(cid:1)
Dependency Injection...........................................................................................................................49(cid:1)
Field Injection..................................................................................................................................49(cid:1)
Setter Injection................................................................................................................................50(cid:1)
Declaring Dependencies......................................................................................................................51(cid:1)
Referencing a Persistence Context.................................................................................................51(cid:1)
Referencing a Persistence Unit.......................................................................................................52(cid:1)
Referencing Enterprise JavaBeans.................................................................................................52(cid:1)
Referencing Server Resources........................................................................................................53(cid:1)
Transaction Management.............................................................................................53(cid:1)
Transaction Review..............................................................................................................................54(cid:1)
Enterprise Transactions in Java...........................................................................................................54(cid:1)
Transaction Demarcation................................................................................................................55(cid:1)
Container-Managed Transactions...................................................................................................56(cid:1)
Bean-Managed Transactions..........................................................................................................58(cid:1)
Using Java EE Components..........................................................................................60(cid:1)
Using a Stateless Session Bean...........................................................................................................60(cid:1)
Using a Stateful Session Bean.............................................................................................................60(cid:1)
Using a Singleton Session Bean..........................................................................................................62(cid:1)
Using a Message-Driven Bean.............................................................................................................62(cid:1)
Adding the Entity Manager...................................................................................................................63(cid:1)
Putting It All Together...................................................................................................64(cid:1)
Defining the Component......................................................................................................................64(cid:1)
Defining the User Interface..................................................................................................................66(cid:1)
Packaging It Up....................................................................................................................................66(cid:1)
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■ CONTENTS
Summary.......................................................................................................................67(cid:1)
■Chapter 4: Object-Relational Mapping................................................................69(cid:1)
Persistence Annotations...............................................................................................69(cid:1)
Accessing Entity State..................................................................................................70(cid:1)
Field Access.........................................................................................................................................70(cid:1)
Property Access...................................................................................................................................71(cid:1)
Mixed Access.......................................................................................................................................71(cid:1)
Mapping to a Table.......................................................................................................73(cid:1)
Mapping Simple Types..................................................................................................74(cid:1)
Column Mappings................................................................................................................................75(cid:1)
Lazy Fetching.......................................................................................................................................76(cid:1)
Large Objects.......................................................................................................................................77(cid:1)
Enumerated Types...............................................................................................................................78(cid:1)
Temporal Types....................................................................................................................................80(cid:1)
Transient State.....................................................................................................................................80(cid:1)
Mapping the Primary Key..............................................................................................81(cid:1)
Overriding the Primary Key Column.....................................................................................................81(cid:1)
Primary Key Types...............................................................................................................................81(cid:1)
Identifier Generation............................................................................................................................82(cid:1)
Automatic Id Generation..................................................................................................................82(cid:1)
Id Generation Using a Table............................................................................................................83(cid:1)
Id Generation Using a Database Sequence.....................................................................................85(cid:1)
Id Generation Using Database Identity............................................................................................86(cid:1)
Relationships................................................................................................................87(cid:1)
Relationship Concepts.........................................................................................................................87(cid:1)
Roles...............................................................................................................................................87(cid:1)
Directionality...................................................................................................................................87(cid:1)
Cardinality.......................................................................................................................................88(cid:1)
Ordinality.........................................................................................................................................89(cid:1)
Mappings Overview..............................................................................................................................90(cid:1)
Single-Valued Associations..................................................................................................................90(cid:1)
Many-to-One Mappings..................................................................................................................90(cid:1)
Using Join Columns........................................................................................................................91(cid:1)
One-to-One Mappings.....................................................................................................................93(cid:1)
Bidirectional One-to-One Mappings................................................................................................94(cid:1)
Collection-Valued Associations............................................................................................................95(cid:1)
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