Tài liệu Enterprise JavaBeans 3.1 ppt

www.it-ebooks.info www.it-ebooks.info Enterprise JavaBeans 3.1 www.it-ebooks.info www.it-ebooks.info SIXTH EDITION Enterprise JavaBeans 3.1 Andrew Lee Rubinger and Bill Burke Beijing • Cambridge • Farnham • Köln • Sebastopol • Tokyo www.it-ebooks.info Enterprise JavaBeans 3.1, Sixth Edition by Andrew Lee Rubinger and Bill Burke Copyright © 2010 Andrew Lee Rubinger and William J. Burke, Jr. All rights reserved. Printed in the United States of America. Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472. O’Reilly books may be purchased for educational, business, or sales promotional use. Online editions are also available for most titles (http://my.safaribooksonline.com). For more information, contact our corporate/institutional sales department: (800) 998-9938 or corporate@oreilly.com. Editor: Mike Loukides Production Editor: Teresa Elsey Copyeditor: Genevieve d’Entremont Proofreader: Teresa Elsey Indexer: John Bickelhaupt Cover Designer: Karen Montgomery Interior Designer: David Futato Illustrator: Robert Romano Printing History: June 1999: First Edition. March 2000: Second Edition. September 2001: Third Edition. June 2004: Fourth Edition. May 2006: Fifth Edition. September 2010: Sixth Edition. Nutshell Handbook, the Nutshell Handbook logo, and the O’Reilly logo are registered trademarks of O’Reilly Media, Inc. Enterprise JavaBeans 3.1, Sixth Edition, the image of a wallaby and joey, and related trade dress are trademarks of O’Reilly Media, Inc. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and O’Reilly Media, Inc., was aware of a trademark claim, the designations have been printed in caps or initial caps. While every precaution has been taken in the preparation of this book, the publisher and authors assume no responsibility for errors or omissions, or for damages resulting from the use of the information con- tained herein. ISBN: 978-0-596-15802-6 [M] 1283539129 www.it-ebooks.info Table of Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv Part I. Why Enterprise JavaBeans? 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 The Problem Domain 3 Breaking Up Responsibilities 3 Code Smart, Not Hard 6 The Enterprise JavaBeans™ 3.1 Specification 8 Review 10 2. Component Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Server-Side Component Types 12 Session Beans 12 Message-Driven Beans (MDBs) 15 Entity Beans 16 The Java Persistence Model 17 The Model Isn’t Everything 17 3. Container Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Dependency Injection (DI) 20 Concurrency 21 Instance Pooling/Caching 21 Transactions 23 Security 23 Timers 24 Naming and Object Stores 24 Interoperability 25 Lifecycle Callbacks 25 Interceptors 26 v www.it-ebooks.info Platform Integration 27 Bringing It Together 27 4. Developing Your First EJBs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Step 1: Preparation 29 Definitions 29 Naming Conventions 32 Conventions for the Examples 32 Step 2: Coding the EJB 33 The Contract 33 The Bean Implementation Class 34 Out-of-Container Testing 35 Integration Testing 36 Summary 39 Part II. Server-Side Component Models 5. The Stateless Session Bean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 The XML Deployment Descriptor 45 SessionContext 46 EJBContext 47 The Lifecycle of a Stateless Session Bean 49 The Does Not Exist State 50 The Method-Ready Pool 50 Example: The EncryptionEJB 52 The Contract: Business Interfaces 53 Application Exceptions 54 Bean Implementation Class 55 Accessing Environment Properties (Injection and Lookup) 57 Asynchronous Methods 60 6. The Stateful Session Bean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 The Lifecycle of a Stateful Session Bean 64 The Does Not Exist State 65 The Method-Ready State 65 The Passivated State 66 Example: The FileTransferEJB 68 The Contract: Business Interfaces 69 Exceptions 70 Bean Implementation Class 70 POJO Testing Outside the Container 74 Integration Testing 77 vi | Table of Contents www.it-ebooks.info 7. The Singleton Session Bean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Concurrency 82 Shared Mutable Access 84 Container-Managed Concurrency 86 Bean-Managed Concurrency 87 Lifecycle 87 Explicit Startup 87 Example: The RSSCacheEJB 88 Value Objects 89 The Contract: Business Interfaces 92 Bean Implementation Class 92 8. Message-Driven Beans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 JMS and Message-Driven Beans 98 JMS as a Resource 98 JMS Is Asynchronous 99 JMS Messaging Models 100 Learning More About JMS 103 JMS-Based Message-Driven Beans 103 @MessageDriven 103 The Lifecycle of a Message-Driven Bean 108 The Does Not Exist State 109 The Method-Ready Pool 109 Connector-Based Message-Driven Beans 111 Message Linking 114 Session Beans Should Not Receive Messages 114 The JMS APIs 115 Example: The StatusUpdateEJBs 118 Part III. EJB and Persistence 9. Persistence: EntityManager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Entities Are POJOs 128 Managed Versus Unmanaged Entities 130 Persistence Context 130 Packaging a Persistence Unit 133 The Persistence Unit Class Set 135 Obtaining an EntityManager 136 EntityManagerFactory 137 Obtaining a Persistence Context 138 Interacting with an EntityManager 140 Example: A Persistent Employee Registry 141 Table of Contents | vii www.it-ebooks.info A Transactional Abstraction 141 Persisting Entities 142 Finding and Updating Entities 144 Removing Entities 147 refresh() 148 contains() and clear() 148 flush() and FlushModeType 148 Locking 149 unwrap() and getDelegate() 149 10. Mapping Persistent Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 The Programming Model 152 The Employee Entity 152 The Bean Class 152 XML Mapping File 154 Basic Relational Mapping 155 Elementary Schema Mappings 155 Primary Keys 157 @Id 157 Table Generators 158 Sequence Generators 159 Primary-Key Classes and Composite Keys 160 Property Mappings 164 @Transient 164 @Basic and FetchType 164 @Lob 166 @Temporal 166 @Enumerated 167 @Embedded Objects 167 11. Entity Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 The Seven Relationship Types 171 One-to-One Unidirectional Relationship 173 One-to-One Bidirectional Relationship 176 One-to-Many Unidirectional Relationship 178 Many-to-One Unidirectional Relationship 181 One-to-Many Bidirectional Relationship 182 Many-to-Many Bidirectional Relationship 184 Many-to-Many Unidirectional Relationship 187 Mapping Collection-Based Relationships 188 Ordered List-Based Relationship 188 Map-Based Relationship 189 Detached Entities and FetchType 190 viii | Table of Contents www.it-ebooks.info [...]... (EJB 3.1 Specification, page 29): The Enterprise JavaBeans architecture is a [sic] architecture for the development and deployment of component-based business applications Applications written using the Enterprise JavaBeans architecture are scalable, transactional, and multi-user secure These applications may be written once, and then deployed on any server platform that supports the Enterprise JavaBeans. .. contract for interaction between the application and container In the case of Enterprise JavaBeans (EJB) 3.1, this contract is provided by a document jointly developed by experts under the authority of the Java Community Process (http://jcp.org) Its job is to do all the work you shouldn’t be doing The Enterprise JavaBeans 3.1 Specification Just as interfaces in code abstract the “what” from the “how,”... Why Enterprise JavaBeans? If your path to Enterprise Java is anything like mine, you’ve arrived here hoping to be more productive in application development Perhaps you’ve heard some good or bad things about this thing called “EJB,” and you’d like to explore some more Perhaps some EJB technology is already in place at work, and you’re looking to understand it a bit deeper The fact is that Enterprise JavaBeans. .. example code does not require permission We appreciate, but do not require, attribution An attribution usually includes the title, author, publisher, copyright holder, and ISBN For example: Enterprise JavaBeans 3.1, Sixth Edition, by Andrew Lee Rubinger and Bill Burke (O’Reilly) Copyright 2010 Andrew Lee Rubinger and William J Burke, Jr., 9780596158026.” If you feel your use of code examples falls... xvi | Preface www.it-ebooks.info Part I, Why Enterprise JavaBeans? Multiuser distributed system are inherently complex To ignore the issues they present is to ask for trouble down the line Luckily, you don’t have to do all the work yourself; Chapters 1 through 4 outline the benefits of taking advantage of EJB—a component model for simplified development of enterprise applications Part II, Server-Side... scalable, transactional, and multi-user secure These applications may be written once, and then deployed on any server platform that supports the Enterprise JavaBeans specification More simply rewritten: Enterprise JavaBeans is a standard server-side component model for distributed business applications This means that EJB defines a model for piecing together a full system by integrating modules Each component... themselves will have a release cycle that outlives this book, so you may want to check back to get bug fixes, enhancements, and other updates as time goes on Software and Versions This book covers EJB 3.1 and Java Persistence 2.0 It uses Java language features from the Java SE 6 platform Because the focus of this book is on developing vendorindependent EJB components and solutions, we have stayed away... and Elements The Element The and Elements UDDI 2.0 From Standards to Implementation 355 356 356 361 368 369 370 370 371 372 374 375 377 379 380 21 EJB 3.1 and Web Services 381 Accessing Web Services with JAX-RPC Generating JAX-RPC Artifacts from WSDL Calling a Service from an EJB The Deployment... Dan Allen, and Pete Muir: your work has made the examples portion of this book possible, and I’ve no doubt that we’re on the cusp of a revolution that will bring simplicity back to functional testing of Enterprise Java Let’s keep plugging The JBoss Boston User’s Group gave me a stage and place to geek out with friends Until the next meeting, Jesper Pedersen, Shelly McGowan, Scott Marlow, and John Doyle... manual database connections No more object pools or caches It meant no more speaking like a computer It meant writing the programs I wanted to build, not the mechanics underneath My experience with this enterprise software miraculously made me marketable enough to snag a post-college job in the middle of the dot-com fallout, and during my tenure there we enrolled in a weeklong training session from the . Events 33 3 Custom Injection Annotations 33 3 Exception Handling 33 5 Aborting a Method Invocation 33 6 Catch and Rethrow Exceptions 33 6 Interceptor Lifecycle 33 8 Bean. Contents www.it-ebooks.info Cascading 19 1 PERSIST 19 2 MERGE 19 2 REMOVE 1 93 REFRESH 1 93 ALL 1 93 When to Use Cascading 19 4 12 . Entity Inheritance . . . . . .