A Programmer's Guide to

Transcription

1 J2EE FrontEnd Technologies: A Programmer's Guide to Servlets, JavaServer Pages, and Enterprise JavaBeans LENNART JGRELID APress Media, LLC

2 J2EE FrontEnd Technologies: A Programmer's Guide to Servlets, JavaServer Pages, and Enterprise JavaBeans Copyright 2002 by Lennart Jorelid Originally published by Apress in 2002 AII rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written perrnission of the copyright owner and the publisher. ISBN ISBN (ebook) DOI / Trademarked names may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, we use the names only in an editorial fashion and to the benefit ofthe trademark owner, with no intention ofinfringement ofthe trademark. Editorial Directors: Dan Appleman, Gary Cornell, Jason Gilmore, Karen Watterson Marketing Manager: Stephanie Rodriguez Technical Reviewers: Janet Traub, Steve Clase, David Czarnecki Project Manager: Carol Burbo Developmental Editor: Valerie Perry Copy Editors: Kim Wimpsett, Tom Gillen Production Editor: Tory McLearn Compositor: Susan Glinert Indexer: Julie Kawabata Cover Designer: Tom Debolski Artist: Alian Rasmussen In the United States, phone SPRINGER, orders@springer-ny. corn, or visit Outside the United States, fax , orders@springer. de, or visit For information on translations, please contact Apress directly at 901 Grayson Street, Suite 204, Berkeley, CA Phone , fax , info@apress. corn, or visit http: 1 /www. apress.corn. The information in this book is distributed onan "as is" hasis, without warranty. Although every precaution has been taken in the preparation of this work, neither the author nor Apress shall ha ve any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the information contained in this work.

3 For Camilla and Lotta

4 Contents at a Glance Acknowledgments... xi About the Author... xiii Part I Chapter 1 Chapter 2 Chapter 3 Part II Chapter 4 Chapter 5 Chapter 6 Servlets... 1 Servlet Theory... 3 Sharing Servlet Resources Servlet Examples JSP JavaServer Pages JSP Tag Libraries JSP Examples Part III Struts Chapter 7 The Apache Struts Framework Walkthrough Part IV EJB Chapter 8 Integrating with the Business Tier Chapter 9 Example 1: Centralizing Exchange Rates Chapter 10 Example 2: Refactoring an Old-Style Web Application Chapter 11 Example 3: Entity EJBs for Database Integration Part V Appendix Appendix A The Java 2 Enterprise Edition Reference Implementation Server Index

5 Contents Acknowledgments... xi About the Author... xiii Part I Servlets... 1 Chapter 1 Servlet Theory... 3 What Are Servlets?... 3 The J2EE Approach to Servlets... 5 Touring the javax. servlet Package Touring the javax.servlet.http Package Maintaining State in an HTTP Connection Chapter 2 Sharing Servlet Resources What Are the Forwarding and Including Patterns? Leading-Edge Patterns-in a State of Flux Sharing Resources between Servlets-A UML Approach Sharing a PingerServlet Resource Chapter 3 Servlet Examples Shopping Cart Servlet The Servlet Mediator (HTTP Tunneling Servlet) Proceeding with Your Servlet Development

6 Contents Part II JSP Chapter 4 JavaServer Pages Why JavaServer Pages? Creating a JSP Document Chapter 5 JSP Tag Libraries Describing Tags The Life Cycle of a Tag Handler Class IterationTag Interface Touring the javax.servlet.jsp. tagext Package The Role of JSP Tag Libraries in Middle- Tier System Development Chapter 6 JSP Examples Using JSP Standard Objects Custom JSP Tags-Nesting and Looping The If- Then-Else Custom JSP Tag Example Part III Struts Chapter 7 The Apache Struts Framework Walkthrough Overview of the Struts Architecture Struts Controller Components Struts Model Components Struts View Components The View and JSP Documents Error Handling in the Survey Wizard Application Reflections on the Struts Framework Walkthrough Example viii

7 Contents Part IV EJB Chapter 8 Integrating with the Business Tier Reviewing the Structure of a J2EE Application Advantages of Using a Separate Business Logic Layer The EJB Development Process The EJB Life Cycle EJB Deployment Descriptors Touring the javax.ejb Package Chapter 9 Example 1: Centralizing Exchange Rates Using a Stateless Session EJB Component Chapter 10 Example 2: Refactoring an Old-Style Web Application The View of the Old-Style Web Application The Model of the Old-Style Web Application Creating a Generic EJB Facade for the Database The LegacyFacade EJB Component Deployment Descriptor The Web Application Deployment Structure Chapter 11 Example 3: Entity EJBs for Database Integration Step l-jndi Registry Cleanup Step 2-DataSource Schema Modification Step 3-Implementing the Image Subsystem Step 4-Configuring the Image Subsystem Step 5-Implementing the WebPage Search System Classes Step 6-Configuring the WebPage Search System Reflections on the Second Refactoring Step ix

8 Contents Part V Appendix Appendix A The Java 2 Enterprise Edition Reference Implementation Server Configuring the Server Deploying J2EE Application Components Application Deployment in the J2EE 1.3 Reference Implementation Server Configuring the J2EEv1.3 Server Deploying J2EE Application Components Index x

9 Acknowledgments THIs BOOK HAS HAD a long and complex writing process. The specifications of all the topics covered have changed at least once during the project. Despite my constant effort to modify the text and images to reflect the changes, the many people who had a part in the book's development have accepted change with a smile. At Apress, I would like to thank Gary Cornell, Grace Wong, and Carol Burbo for believing in the project and providing structure to the writing process. Special thanks to the technical editors Janet Traub, Steve Close, and David Czarnecki who provided invaluable assistance in the development process. Many thanks to the editors Valerie Perry, Tom Gillen, and Kim Wunpsett who read, pondered, and suggested restructuring. Their skills are what separate my scattered bursts of information from the quality structure of this book. For an infinite patience and the ever-present warm smile despite my prolonged absence from social and worldly events, my grateful thanks go to Camilla, Lars, and Margareta. For relatives, friends, and family to whom I must have been a complete stranger during this project, I direct my most mischievous apologies. xi

10 About the Author WITH WORKING EXPERIENCE THAT spans projects in the United States, Canada, United Kingdom, Switzerland, Sweden, and Germany, Lennart is a recognized expert, architect, and educator in the Java technology community. His key skills are in the object -oriented analysis, design, and programming ofjava 2 Enterprise Edition (J2EE) systems. Through his affiliation as Java Manager with jguru (one of the most popular Web sites for Java developers), he has explained Java technology to thousands of programmers. Before joining j Guru. com, Lennart was Senior Java Consultant and Systems Designer for NetGuide Scandinavia in G6teborg, Sweden. His focus is server-side Java and electronic-commerce application systems. He is fluent in many programming languages, as well as most J2EE server-side technologies. Lennart has a master's degree in Engineering Physics from Chalmers University of Technology in Sweden. xiii