Jakarta struts for dummies

406 Pages·2004·5.645 MB·English

by  Mike Robinson, Ellen Finkelstein

01 559575 FM.qxd 3/2/04 3:53 PM Page i
Jakarta Struts
FOR
DUMmIES
‰
by Mike Robinson and

Ellen Finkelstein
01 559575 FM.qxd 3/2/04 3:53 PM Page ii
Jakarta Struts For Dummies®
Published by
Wiley Publishing, Inc.
111 River Street
Hoboken, NJ 07030-5774
Copyright © 2004 by Wiley Publishing, Inc., Indianapolis, Indiana
Published by Wiley Publishing, Inc., Indianapolis, Indiana
Published simultaneously in Canada
No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form
or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as
permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior
written permission of the Publisher, or authorization through payment of the appropriate per-copy
fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, [phone], fax
[phone]. Requests to the Publisher for permission should be addressed to the Legal Department,
Wiley Publishing, Inc., 10475 Crosspoint Blvd., Indianapolis, IN 46256, [phone], fax [phone],
e-mail: [email protected].
Trademarks: Wiley, the Wiley Publishing logo, For Dummies, the Dummies Man logo, A Reference for the
Rest of Us!, The Dummies Way, Dummies Daily, The Fun and Easy Way, Dummies.com, and related trade
dress are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the United
States and other countries, and may not be used without written permission. All other trademarks are the
property of their respective owners. Wiley Publishing, Inc., is not associated with any product or vendor
mentioned in this book.
LIMIT OF LIABILITY/DISCLAIMER OF WARRANTY: THE PUBLISHER AND THE AUTHOR MAKE NO REP­
RESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE
CONTENTS OF THIS WORK AND SPECIFICALLY DISCLAIM ALL WARRANTIES, INCLUDING WITHOUT
LIMITATION WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE. NO WARRANTY MAY BE CRE­
ATED OR EXTENDED BY SALES OR PROMOTIONAL MATERIALS. THE ADVICE AND STRATEGIES CON­
TAINED HEREIN MAY NOT BE SUITABLE FOR EVERY SITUATION. THIS WORK IS SOLD WITH THE
UNDERSTANDING THAT THE PUBLISHER IS NOT ENGAGED IN RENDERING LEGAL, ACCOUNTING, OR
OTHER PROFESSIONAL SERVICES. IF PROFESSIONAL ASSISTANCE IS REQUIRED, THE SERVICES OF A
COMPETENT PROFESSIONAL PERSON SHOULD BE SOUGHT. NEITHER THE PUBLISHER NOR THE
AUTHOR SHALL BE LIABLE FOR DAMAGES ARISING HEREFROM. THE FACT THAT AN ORGANIZATION
OR WEBSITE IS REFERRED TO IN THIS WORK AS A CITATION AND/OR A POTENTIAL SOURCE OF FUR­
THER INFORMATION DOES NOT MEAN THAT THE AUTHOR OR THE PUBLISHER ENDORSES THE
INFORMATION THE ORGANIZATION OR WEBSITE MAY PROVIDE OR RECOMMENDATIONS IT MAY
MAKE. FURTHER, READERS SHOULD BE AWARE THAT INTERNET WEBSITES LISTED IN THIS WORK
MAY HAVE CHANGED OR DISAPPEARED BETWEEN WHEN THIS WORK WAS WRITTEN AND WHEN IT
IS READ.
For general information on our other products and services or to obtain technical support, please contact
our Customer Care Department within the U.S. at 800-762-2974, outside the U.S. at 317-572-3993, or fax
317-572-4002.
Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may
not be available in electronic books.
Library of Congress Control Number: 2004101960
ISBN: 0-7645-5957-5
Manufactured in the United States of America
10 9 8 7 6 5 4 3 2 1
1O/RZ/QT/QU/IN
01 559575 FM.qxd 3/2/04 3:53 PM Page iii
About the Authors

Mike Robinson has been working in the computing field since, well, when
minicomputers were popular. He has a master’s degree in computer science
and has been an independent Java developer specializing in interactive Web
applications since 1998. Mike is an adjunct faculty member in the Computer
Science Department at Maharishi University of Management in Fairfield, Iowa.
If he had any spare time, he would probably spend it hiking.
Ellen Finkelstein is the author of numerous best-selling computer books on
AutoCAD, PowerPoint, Flash, and most recently OpenOffice.org. She writes
regular articles on AutoCAD and PowerPoint in magazines, e-zines, and for
Web sites. She is an adjunct Instructor of Management, teaching e-business
courses to M.B.A. students. She writes at home so that she can take the bread
out of the oven on time.
01 559575 FM.qxd 3/2/04 3:53 PM Page v
Dedication

To MMY, for explaining the organizing power of Natural Law that sustains the
existence and evolution of the entire universe and showing us how to make use
of this power in our daily lives to achieve maximum results through minimum
effort.
Authors’ Acknowledgments

Mike Robinson
First and foremost I have to thank my co-author, Ellen Finkelstein, who initiated
me into the ins and outs of writing a book. Ellen is the epitome of cool under
the pressure of deadlines. She always manages to have a great sense of humor
and shiny outlook regardless of the situation. Thanks for your patience.
Thanks to my wife, Pat, who is always my guiding inspiration.
Ellen Finkelstein
I’d like to start out by thanking Mike Robinson for his extensive knowledge and
experience, clear thinking, integrity, sense of responsibility, and great flexibility.
Mike is the fountain of knowledge for this book. He is always a pleasure to work
with.
Thanks to my husband, Evan, and kids, Yeshayah and Eliyah (who want to
see their names in a book), who support me while I’m writing, writing, and
writing some more.
Collectively
At Wiley, our esteemed publisher, we’d like to thank Terri Varveris, our acqui­
sitions editor, for her ever-lively support. Both Linda Morris and Susan Pink
were our able project editors, keeping track of innumerable details, including
chapters, figures, and by how many pages we were over our quota. They kept
us on track and made it easy.
Thanks to Peter Just, our friend and colleague, who did a thorough and care­
ful job of technical editing, making sure that our terms and code were correct
and that we were consistent and clear. He also contributed the material for
Chapter 5.
01 559575 FM.qxd 3/2/04 3:53 PM Page vi
Publisher’s Acknowledgments
We’re proud of this book; please send us your comments through our online registration form
located at www.dummies.com/register/.
Some of the people who helped bring this book to market include the following:
Acquisitions, Editorial, and Production
Media Development
Project Coordinator: Nancee Reeves
Project Editors: Susan Pink and Linda Morris
Layout and Graphics: Andrea Dahl,

Acquisitions Editor: Terri Varveris Lauren Goddard, Denny Hager,

Lynsey Osborn, Heather Ryan,

Technical Editor: Peter Just
Jacque Schneider

Editorial Manager: Carol Sheehan
Proofreaders: Andy Hollandbeck,

Permissions Editor: Laura Moss Carl William Pierce,

Media Development Manager: TECHBOOKS Production Services

Laura VanWinkle Indexer: TECHBOOKS Production Services
Media Development Supervisor:
Richard Graves
Editorial Assistant: Amanda Foxworth
Cartoons: Rich Tennant (www.the5thwave.com)
Publishing and Editorial for Technology Dummies
Richard Swadley, Vice President and Executive Group Publisher
Andy Cummings, Vice President and Publisher
Mary C. Corder, Editorial Director
Publishing for Consumer Dummies
Diane Graves Steele, Vice President and Publisher
Joyce Pepple, Acquisitions Director
Composition Services
Gerry Fahey, Vice President of Production Services
Debbie Stailey, Director of Composition Services
01 559575 FM.qxd 3/2/04 3:53 PM Page vii
Contents at a Glance

Introduction .................................................................1
Part I: Getting to Know Jakarta Struts ..........................7
Chapter 1: Starting with the Basics .................................................................................9
Chapter 2: Laying the Groundwork ...............................................................................25
Chapter 3: Creating a Simple Web Application with Struts ........................................47
Part II: Starting from the Core ....................................89
Chapter 4: Controlling with the Controller ..................................................................91
Chapter 5: Creating the Model .....................................................................................109
Chapter 6: Designing the View .....................................................................................137
Chapter 7: Setting the Configuration ..........................................................................159
Part III: Expanding Your Development Options ...........189
Chapter 8: Exceptions to the Rule ...............................................................................191
Chapter 9: Getting Friendly with Plug-ins ...................................................................209
Chapter 10: Getting a Helping Hand with Tag Libraries ...........................................225
Chapter 11: Working with Page Composition Techniques .......................................249
Chapter 12: Securing Your Application ......................................................................265
Part IV: Putting It All Together .................................279
Chapter 13: Logging Your Actions ...............................................................................281
Chapter 14: Creating the MusicCollection.com Application ....................................287
Part V: The Part of Tens ...........................................327
Chapter 15: Ten Helpful Extensions to Struts ............................................................329
Chapter 16: Ten Ways to Find More Information .......................................................337
Part VI: Appendixes .................................................345
Appendix A: Struts-EL and JSTL Tag Library Syntax .................................................347
Appendix B: Glossary ...................................................................................................375
Index .......................................................................379
01 559575 FM.qxd 3/2/04 3:53 PM Page ix
Table of Contents

Introduction ..................................................................1
About This Book ..............................................................................................1
How to Use This Book ....................................................................................2
Foolish Assumptions ......................................................................................2
Conventions Used in This Book ....................................................................3
How This Book Is Organized ..........................................................................3
Part I: Getting to Know Jakarta Struts ...............................................4
Part II: Starting from the Core ..............................................................4
Part III: Expanding Your Development Options .................................4
Part IV: Putting It All Together .............................................................4
Part V: The Part of Tens ........................................................................4
Part VI: Appendixes ...............................................................................5
Icons Used in This Book .................................................................................5
Where to Go from Here ...................................................................................5
Part I: Getting to Know Jakarta Struts ...........................7
Chapter 1: Starting with the Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
What Is Jakarta Struts? ...................................................................................9
Structuring a Web Application ....................................................................11
Using Java Servlets ..............................................................................12
Creating JavaServer Pages .................................................................13
Using JavaBeans ..................................................................................14
Understanding the Model-View-Controller Design Pattern .....................17
What is a design pattern? ...................................................................18
The MVC design pattern .....................................................................18
How Struts enforces the MVC pattern ..............................................19
Chapter 2: Laying the Groundwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Getting Java ....................................................................................................26
Downloading and installing Java .......................................................26
Setting the Java Home environment variable ..................................28
Getting the Web Container ...........................................................................29
Downloading Tomcat to Windows ....................................................29
Installing Tomcat under Windows .....................................................29
Installing Tomcat under Linux or Mac OS X .....................................31
Starting and testing Tomcat ...............................................................32
01 559575 FM.qxd 3/2/04 3:53 PM Page x
x
Jakarta Struts For Dummies
Choosing Your Development Environment ................................................33
Downloading and Installing Eclipse ............................................................34
Getting the Tomcat Launcher Plug-in for Eclipse .....................................35
Downloading and installing the Tomcat Launcher plug-in ............35
Configuring the Tomcat Launcher plug-in ........................................36
Getting Struts .................................................................................................39
Downloading Struts .............................................................................40
Reviewing the components of Struts ................................................41
Testing Your Web Application Development Environment .....................43
Chapter 3: Creating a Simple Web Application with Struts . . . . . . . .47
Designing Your First Struts Application .....................................................48
Application requirements ...................................................................48
Determining which components to use ............................................49
Putting Everything in Place .........................................................................49
Creating the project in Eclipse ..........................................................50
Setting up the application folders .....................................................52
Importing the Struts files ....................................................................54
Creating the JavaServer Pages ....................................................................59
The login.jsp page ...............................................................................59
The loggedin.jsp page .........................................................................64
Using message resources ...................................................................67
Making the Formbean ...................................................................................69
Adding a JavaBean ........................................................................................74
Creating an Action .........................................................................................75
Configuring Struts .........................................................................................78
Defining web.xml .................................................................................78
Configuring Struts with struts-config.xml ........................................81
Strutting Your Stuff: Running the Application ...........................................85
Deploying the Login application .......................................................85
Testing the application .......................................................................85
Debugging with Eclipse ......................................................................87
Part II: Starting from the Core .....................................89
Chapter 4: Controlling with the Controller . . . . . . . . . . . . . . . . . . . . . . .91
Understanding the Struts Controller Classes ............................................91
Working with the Master Controller — the ActionServlet .......................93
Starting the Servlet .............................................................................94
Processing requests ............................................................................97
Shutting down the Servlet ..................................................................97
Working with the Controller’s Helper — RequestProcessor ...................98
Getting Down to Work: Extending ActionClass .......................................100
Using the execute method ................................................................101
Predefined Action classes ................................................................103
Action Forms ......................................................................................108
01 559575 FM.qxd 3/2/04 3:53 PM Page xi
xi

Table of Contents
Chapter 5: Creating the Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109
Understanding the Model ..........................................................................109
Working with Business Objects .................................................................110
Meeting requirements for business objects ..................................111
Adding helper classes .......................................................................112
Using JavaBeans ................................................................................112
Implementing the Model ............................................................................112
Achieving persistence .......................................................................113
Getting MySQL .............................................................................................113
Downloading and installing MySQL ................................................114
Downloading MySQL Connector/J ..................................................114
Setting Up Your IDE and Web Container ..................................................115
Importing the class library into Eclipse .........................................115
Adding the class library to Tomcat .................................................116
Working with MySQL ..................................................................................117
Starting and stopping MySQL ..........................................................118
Creating a database ...........................................................................120
Creating a table in MySQL ................................................................121
Inserting data in the users table ......................................................121
Executing queries ..............................................................................122
Exiting the MySQL command tool ...................................................123
Connecting the Model to the Database ....................................................123
Working with JDBC ............................................................................124
Retrieving multiple records .............................................................126
Pooling Connections ...................................................................................130
Jakarta Commons DBCP ...................................................................131
Using connection pooling .................................................................132
Configuring the data source in Struts .............................................134
Chapter 6: Designing the View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
Choosing JSP or an Alternative .................................................................137
Template engines ...............................................................................137
XML tools ...........................................................................................139
Internationalization .....................................................................................139
Creating multinational applications ................................................140
Using one source for String type constants ...................................148
Mediating between the View and the Controller ....................................149
Configuring the formbean ................................................................150
Interactions with the formbean .......................................................151
Preparing the form with the reset method ....................................152
Indexing data ......................................................................................152
Validating data ...................................................................................152
Declarative form validation ..............................................................154
Notifying Users of Problems ......................................................................154
Mediating Automatically ............................................................................155
Configuring the DynaActionForm class ..........................................156
Differences between ActionForm and DynaActionForm ..............157
01 559575 FM.qxd 3/2/04 3:53 PM Page xii
xii
Jakarta Struts For Dummies
Chapter 7: Setting the Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . .159
Stringing the Parts Together ......................................................................159
Editing the Web Container Configuration File .........................................160
The ServletContext configuration tag .............................................162
Listener configuration ......................................................................163
ActionServlet configuration .............................................................163
ActionServlet mapping .....................................................................166
Adding in the tag libraries ................................................................166
A complete example of a web.xml file ............................................167
Modifying the Struts Configuration File ...................................................169
DataSource configuration .................................................................169
Formbean configuration ...................................................................171
Global exceptions ..............................................................................174
Global forwards .................................................................................175
Action mapping .................................................................................176
Controller configuration ...................................................................179
Message resource configuration .....................................................181
Plug-in configuration .........................................................................183
Complete example of a struts-config.xml file .................................184
Part III: Expanding Your Development Options ............189
Chapter 8: Exceptions to the Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . .191
Java Errors and Exceptions .......................................................................192
Try/catch block .................................................................................192
Throwing exceptions ........................................................................193
Wrapping it up in finally ...................................................................194
Exception Strategies ...................................................................................196
Catching exceptions ..........................................................................196
Exception information ......................................................................196
Writing Your Own Exception Classes .......................................................197
Using Chained Exceptions .........................................................................198
Asserting Yourself .......................................................................................199
Handling Exceptions Yourself ....................................................................201
Saving information ............................................................................202
Recovering from errors ....................................................................202
Inform the user ..................................................................................202
Fail gracefully .....................................................................................202
Declarative Exception Handling ................................................................203
Declaring the exception ....................................................................204
Global or local exception handling .................................................204
Extending ExceptionHandler .....................................................................205
Handling RuntimeExceptions in Struts ....................................................207