Tài liệu Art of Java Web Development P1 pptx

MANNING
Neal Ford
STRUTS
TAPESTRY
COMMONS
VELOCITY
JUNIT
AXIS
COCOON
INTERNETBEANS
WEBWORK
ART
OF
JAVA WEB
DEVELOPMENT

Art of Java
Web Development

Art of Java
Web Development
STRUTS, TAPESTRY, COMMONS, VELOCITY, JUNIT,
AXIS, COCOON, INTERNETBEANS, WEBWORK
NEAL FORD
MANNING
Greenwich
(74° w. long.)
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1 2 3 4 5 6 7 8 9 10 – VHG – 08 07 06 05 04 03
To Chuck,
who still teaches me stuff daily

vii
brief contents
PART ITHE EVOLUTION OF WEB ARCHITECTURE
AND DESIGN 1
1 ■ State-of-the-art web design 3
2
■ Building web applications 27
3

■ Creating custom JSP tags 61
4
■ The Model 2 design pattern 91
PART II WEB FRAMEWORKS 131
5 ■ Using Struts 133
6
■ Tapestry 159
7
■ WebWork 199
8
■ InternetBeans Express 227
9
■ Velocity 261
10
■ Cocoon 283
11
■ Evaluating frameworks 311
viii BRIEF CONTENTS
PART III BEST PRACTICES 327
12 ■ Separating concerns 329
13
■ Handling flow 371
14
■ Performance 409
15
■ Resource management 445
16
■ Debugging 475
17
■ Unit testing 521

18
■ Web services and Axis 543
19
■ What won’t fit in this book 563
ix
contents
preface xvii
acknowledgments xix
about the book xxi
about the cover illustration xxx
PART ITHE EVOLUTION OF WEB ARCHITECTURE
AND DESIGN 1
1
State-of-the-art web design 3
1.1 A brief history of Java web development 4
1.2 The importance of design patterns 6
The Model-View-Controller design pattern 7
■
The emergence of
Model 2 9
■
Evolution 10
1.3 Using frameworks 11
A flavor of the Struts framework 12
■
A flavor of the Turbine
framework 14
■
Objectively choosing a framework 20
1.4 Best practices 20

Business rules 20
■
Where should the rules reside? 22
Leveraging best practices 24
1.5 Summary 25
x CONTENTS
2
Building web applications 27
2.1 Building web applications with servlets 29
The eMotherEarth servlet application 29
Evaluating the servlet approach 50
2.2 Building web applications with JSP 50
The JSP eMotherEarth application 51
Evaluating the JSP approach 59
2.3 Summary 60
3
Creating custom JSP tags 61
3.1 The case for custom tags 62
3.2 The tag interfaces 63
The Tag interface 63
■
The IterationTag interface 64
The BodyTag interface 65
3.3 Building simple tags 66
The HtmlSqlResult tag 66
■
Registering the tag 71
3.4 Validating tag attributes 75
Adding DbPool to the application tag 75
3.5 Using prebuilt tags 80

Using JSTL 81
■
Using other taglibs 84
3.6 Custom tag considerations 86
Resource usage 87
■
Building a framework 88
3.7 Now that we’re here, where are we? 88
3.8 Summary 89
4
The Model 2 design pattern 91
4.1 Using Model 2 as your framework 92
The Model 2 schedule application 93
Options in Model 2 116
4.2 Parameterizing commands with controller servlets 117
An example of parameterizing commands 118
Advantages and disadvantages 127
4.3 Summary 128
CONTENTS xi
PART II WEB FRAMEWORKS 131
5
Using Struts 133
5.1 Building Model 2 Web applications with Struts 134
The Struts schedule application 134
■
Value objects as form
beans 136
■
Objectifying commands with Struts’ actions 137
Configuring Struts applications 139

■
Using Struts’ custom tags
to simplify JSP 142
■
Internationalization with Struts 145
Struts’ support for data entry 147
■
Declarative validations 151
5.2 Evaluating Struts 156
5.3 Summary 157
6
Tapestry 159
6.1 Overview 160
6.2 The architecture 160
6.3 A simple Tapestry application 162
Tapestry Hello, World 162
6.4 The Tapestry framework 167
Framework classes and interfaces 167
■
Components 170
6.5 Scheduling in Tapestry 173
Bootstrapping the application 173
■
The Home page 176
The custom table component 180
■
The Add page 185
6.6 Evaluating Tapestry 192
Documentation and samples 192
■

Debugging support 195
Using Tapestry 196
6.7 Summary 197
7
WebWork 199
7.1 Overview 200
The architecture 201
■
The configuration 202
7.2 Key concepts 203
Actions 204
■
Key interfaces 204
■
The value stack 205
Expression language 206
■
BeanInfo classes 207
Templates 207
xii CONTENTS
7.3 Scheduling in WebWork 208
The configuration 208
■
The View page 209
The Add page 214
■
Validations 220
7.4 Evaluating WebWork 224
7.5 Summary 226
8

InternetBeans Express 227
8.1 Overview 228
8.2 The architecture 230
DataExpress 230
■
InternetBeans Express 233
8.3 InternetBeans Express components 234
ixPageProducer 234
■
ixComponents 236
8.4 Scheduling with InternetBeans 237
Data connectivity 238
■
The View page 242
■
The Add
page 245
■
Validations 249
8.5 JSP custom tags 255
8.6 Evaluating InternetBeans Express 257
Documentation and samples 257
Using InternetBeans Express 258
8.7 Summary 259
9
Velocity 261
9.1 Overview 262
9.2 The architecture 263
9.3 Key concepts 265
Setting up Velocity 265

■
The Velocity Template
Language 268
■
Context 269
9.4 Scheduling with Velocity 269
The View page 271
■
The Add page 274
Validations 278
CONTENTS xiii
9.5 Evaluating Velocity 281
Documentation and samples 281
■
Using Velocity 282
9.6 Summary 282
10
Cocoon 283
10.1 Overview 284
10.2 The architecture 285
The publishing framework 285
■
The web framework 288
10.3 Key concepts 289
The publishing framework 289
■
The sitemap 295
The web framework 299
10.4 Scheduling in Cocoon 302
The sitemap 303

■
The action 304
■
The view 305
10.5 Evaluating Cocoon 307
Documentation and samples 307
■
Source code 308
Debugging 308
10.6 Summary 309
11
Evaluating frameworks 311
11.1 Evaluation criteria 312
Suitability to the application 312
■
Documentation 315
Source code 316
■
Tool support 317
■
External criteria 318
11.2 Design considerations 319
Adherence to good design principles 319
■
The user
interface 320
■
Innovative features 321
Insularity 322
■

“Feel” 322
11.3 What I like 323
Transparent infrastructure 323
■
Innovative ideas 323
Ultra-high cohesion and low coupling 324
Evaluating frameworks as a hobby 324
11.4 Summary 324
xiv CONTENTS
PART III BEST PRACTICES 327
12
Separating concerns 329
12.1 Using interfaces to hide implementation 330
JDBC interfaces 331
■
Interfaces in frameworks 331
Decoupled classes 332
12.2 Using JavaBeans 333
Model beans 334
12.3 Using Enterprise JavaBeans 337
The EJB architecture 338
■
Porting from JavaBeans to Enterprise
JavaBeans 340
■
Using EJBs in web frameworks 360
Managing JNDI context 361
12.4 Performing validations with model beans 362
Client-side validations 362
Building client-side validations from the server 365

12.5 Summary 368
13
Handling flow 371
13.1 Application usability options 372
Building the base: eMotherEarth.com 372
■
Page-at-a-time
scrolling 378
■
Sortable columns 384
User interface techniques in frameworks 389
13.2 Building undo operations 390
Leveraging transaction processing 391
■
Using the Memento
design pattern 394
■
Undo in frameworks 401
13.3 Using exception handling 401
The difference between technical and domain exceptions 401
Creating custom exception classes 402
■
Where to catch and
handle exceptions 403
■
Exceptions in frameworks 406
13.4 Summary 407
14
Performance 409
14.1 Profiling 410

Measuring memory 410
■
Performance profiling 412
Load testing 419
■
Performance of profiling frameworks 421
CONTENTS xv
14.2 Common performance pitfalls 421
Object creation 422
■
Extraneous object references 424
String usage 426
14.3 Pooling 427
Simple object pools 427
■
Soft and weak references 428
Commons pools 433
■
Pooling in frameworks 440
14.4 Designing for scalability 440
When to scale up to EJB 441
Molding your architecture for the future 441
14.5 When to optimize 442
14.6 Summary 443
15
Resource management 445
15.1 Caching strategies 446
Caching with the Flyweight design pattern 447
■
Caching with

the Façade design pattern 453
■
Resource management
in frameworks 469
15.2 Other resources you need to manage 470
Effectively using JNDI 470
■
Using lazy instantiation 472
Working with web collections 472
15.3 Summary 473
16
Debugging 475
16.1 Debugging web applications 476
16.2 Debugging with the SDK 483
Starting the debugger 483
■
Running the debugger 486
Breakpoints and steps 489
■
Accessing variables 490
Effectively using jdb 492
16.3 Debugging with IDEs 493
Debugging with NetBeans 493
■
Debugging with JBuilder 498
Differences between debuggers 502
16.4 Evaluating debuggers 505
16.5 Debugging in frameworks 506
Struts 506
■

Tapestry 507
■
WebWork 507
InternetBeans Express 507
■
Velocity 508
■
Cocoon 508
xvi CONTENTS
16.6 Logging 508
General logging concepts 509
■
SDK logging 512
log4j logging 516
■
Choosing a logging framework 519
Logging in frameworks 519
16.7 Summary 520
17
Unit testing 521
17.1 The case for testing 522
Agile development 522
■
Unit testing in web applications 524
17.2 Unit testing and JUnit 525
Test cases 525
■
Testing entities 525
■
Running tests 528

Test suites 529
■
Testing boundaries 530
■
Tool support 534
17.3 Web testing with JWebUnit 536
JWebUnit TestCases 537
■
Testing complex elements 539
17.4 Summary 541
18
Web services and Axis 543
18.1 Key concepts 544
18.2 Axis 545
Architecture of Axis 546
■
Axis tools 547
18.3 Calling web services 551
18.4 eMotherEarth web services 553
Configuration 553
■
Orders 556
■
Calling the web service 559
18.5 Summary 562
19
What won’t fit in this book 563
19.1 Persistence 564
Plain old Java objects 564
■

Enterprise JavaBeans 564
Java data objects (JDO) 565
■
Hibernate 566
19.2 HTML and the user interface 566
HTML/XHTML 567
■
Cascading Style Sheets 567
19.3 JavaScript 568
19.4 Summary 569
bibliography 570
index 571
xvii
preface
In ancient China (approximately 500 B.C.), Sun Tzu wrote The Art of War. In it, he
described the state of the art in warfare. The book took a universal approach,
describing wide-ranging topics that related to one another only through how they
applied to warfare. In 1961, Julia Child published the classic Mastering the Art of
French Cooking. In her book, she described the essentials of mastering French
cooking. Her book covered an extensive array of topics, including both kitchen
techniques and recipes.
Both of these influential books offered a comprehensive look at the current
thinking in their fields. Each covered a variety of topics, discussing specific tech-
niques and underlying theories. They included concrete, practical advice, and
they talked about the tools available to make the job of warfare (or cooking) easier.
Art of Java Web Development strives for the same breadth and depth of coverage for
web development in Java. It is not a random selection of topics. Rather, it encom-
passes topics that web developers must master to deliver state-of-the-art software. It
also examines the evolution of the cutting edge in web development architecture
and design, describes the best tools (or weapons) available to developers, and

explains specific, practical techniques for improving your web applications.
Most development books today fall into one of two categories:
API or best prac-
tices. The
API books focus on a single API, either from J2EE and Java or, for exam-
ple, an open-source project. A perfect example is Manning’s excellent Struts in
Action, by Ted Husted et al. It takes you through everything you need to know
xviii PREFACE
about how to use Struts. The best (or worst) practices books focus on individual
topics, examining design patterns and coding samples that represent the best (or
worst) ways to perform a certain task. Art of Java Web Development overlaps some of
the topics from these other types of books, but it does so in a synergistic manner,
discussing how all these pieces (and others) combine to create real-world web
applications.
xix
acknowledgments
Writing any book is a daunting task, and the nature of this book made it even
more so. This means that my supporting structure (i.e., my family and friends)
suffered with and supported me even more than usual. For that, they have my
undying gratitude. First, to all my immediate and extended family, thanks for all
your support, especially my mother, Hazel, who bears the most responsibility for
who I am today. Also, thanks to my dad, Geary, along with Sherrie, Elisha, and the
whole menagerie for their support. I would also like to thank Lloyd, Michelle,
John, Madison, and Max (a force of nature) for all their fun and companionship,
along with Mechelle, Mark, Wyatt, and Wade. The whole Shephard clan deserves
a nod, because they care a lot more about me learning to cook the secret family
recipe for Death by Candied Yams than what I put to paper.
I would also like to thank my surrogate family here in Atlanta, as fine a bunch
of people as you will ever meet: Margie, Wright, Melissa, Julie, Walker, Jim, Randy,
and Karen. They have taken Candy and me into their family and made us feel like

one of them.
There are several instructors whom I feel I should acknowledge as well. Being
an instructor myself, I have insight into what it takes to do it right, and these peo-
ple showed me all I know about it. I would like to thank K. N. King at Georgia
State for excellence in computer science, Robert Goetzman for teaching me to
appreciate literature at a finer level, and James Head for being the finest instruc-
tor whose classes I’ve had the pleasure to attend. Dr. Head and the others are
xx ACKNOWLEDGMENTS
shining examples of how quality instructors make fundamental changes to peo-
ple’s lives every day.
The entire crew at
DSW deserves thanks and acknowledgment. I cannot imag-
ine working with a finer group of people, who keep me technically sharp and
firmly planted: Allan, Brooks, David, Emerson, Jamie, Mike, Noah, Shanna, Steve,
and Tim. As long as I’m acknowledging technical folks, the most insane person I
know, Glenn (but he’s from Australia, so that’s
OK), belongs here, along with my
good friends from Vancouver, Michael and Maggie. From the other side of the
world, Masoud, Frank, and Stepan in Frankfurt are also friends whom I see too lit-
tle and too briefly. Among technically inclined friends, I should include a thanks
and acknowledgment to Chris (and his Evil Twin, Dallas), who is currently lost in
Louisiana. I should also thank Steve Mikel, whom I admire because he shows that
it is possible to have an interesting and diverse life.
I would also like to thank everyone at Manning, the best publisher I’ve ever
encountered. Everyone there from the publisher down embodies what a book
company should be. A special thanks goes out to my technical editor, Luigi Vig-
giano, for keeping me honest, along with the rest of the Manning cast, including
(but not limited to) Marjan Bace, Liz Welch, Mary Piergies, Susan Capparelle,
Ann Navarro, and Dottie Marsico. I would also like to thank all the technical
reviewers who spent a great deal of time to make this book better: Jason Carreira,

Erik Hatcher, Shahram Khorsand, Howard Lewis Ship, Steve Loughran, Ted
Neward, Eitan Suez, and Luigi Viggiano. I appreciate their insights, comments,
criticisms, and feedback.
It is virtually impossible to exist in this field if you don’t have activities that fall
completely outside the technical realm. For that I have other circles of friends,
who are vaguely aware of what I do for a living, but frankly could care less. These
include my neighbors, Jamie, Diane, Kitty, and Gail. Another large support group
consists of all my triathlete buddies, who only know me as the slow guy behind
them: Jon, Joan, Jane, and Robert all fall into that group of people who help keep
me sane.
There aren’t many people who span all the above groups (plus some other
groups that I didn’t even mention). In fact, there is really only one: Terry, who
deserves special thanks for support and friendship, who is a good travel partner,
geek, and Tri-geek. And thanks to Stacy for letting him do all that stuff.
Last but certainly not least is the person who both likes and dislikes this book
the most. My beautiful and wonderful wife, Candy, whom I love more than any-
thing, has spent far too long in the company of only Winston and Parker and
deserves more of my time. Honey, this book is finally done, and I’m all yours again.
xxi
about the book
This book is for every Java web developer, regardless of his or her level of exper-
tise. It is designed primarily for intermediate to advanced developers, who under-
stand the specifics of the various web
APIs in Java but haven’t yet mastered the best
way to apply them. It is perfect for developers who have heard terms like Model-
View-Controller and Model 2, but weren’t present for the series of events that led
to the widespread adoption of these best practices. It is also perfect for designers
and architects of web applications because it discusses the implications of archi-
tecture and design at every opportunity.
This book is also well suited to developers who have looked at (and possibly

struggled with) one of the many web frameworks on the market. It is unique in its
coverage of web frameworks, giving equal weight to six different frameworks and
comparing them on equal ground. Whether you are planning to use a framework
or you want to write your own, understanding the similarities and differences
between the existing frameworks will save you a great deal of time. Art of Java Web
Development also illustrates new possibilities for those who are using a framework
but aren’t happy with it.
In addition, this book is aimed at developers who must create applications in
the real world. Many of the best practices books treat each tip as the sole focus of
a chapter, with no discussion of integrating it into a real application. Real applica-
tions are messy, requiring lots of moving parts working together seamlessly. The
best practices in this book are presented in the context of a working e-commerce
xxii ABOUT THE BOOK
application, with all the places that the real world intersects with the academia of
the pattern discussed.
How this book is organized
Art of Java Web Development consists of three parts. It begins with coverage of the his-
tory of the architecture of web applications, highlighting the uses of the standard
web
API to create applications with increasingly sophisticated architectures. The
discussion leads to the development of industry-accepted best practices for archi-
tecture. Instead of simply pronouncing one architecture as the best, Art of Java Web
Development shows the history and evolution of each architecture.
The second part of the book provides a unique overview of the most popular
web application frameworks. Trying to evaluate a framework is difficult because its
documentation typically stresses its advantages but hides its deficiencies. This
book builds the same application in six different frameworks, encouraging you to
perform an “apples to apples” comparison. The last chapter of part 2 provides a
candid evaluation of the pros and cons of each framework to assist you in making
a decision or in evaluating a framework on your own.

The selection of the correct framework is only the beginning of the life cycle of
an application. Part 3 examines best practices, including sophisticated user inter-
face techniques, intelligent caching and resource management, performance tun-
ing, debugging, testing, and web services.
Part 1
Chapter 1 serves as the jumping-off point for the book. It highlights all the topics
to come in the subsequent chapters and explains my primary motivation for writ-
ing the book.
Chapter 2 begins our discussion of the evolution of web applications. The idea
behind this chapter is to present an application built by a developer who is very
good with Java and understands the web
APIs but hasn’t yet applied best practices
and architecture. The first pass at the application uses only servlets (which was the
only tool available when the web
APIs first debuted). Then we build the same
application using just
JSP. In both cases, we highlight the strengths and weak-
nesses of the resulting applications.
Chapter 3 carries the evolution a step further with custom tags. It takes the
JSP
application built in the second chapter and improves it using custom JSP tags.
Chapter 4 represents the culmination of the evolution of architecture and
design. Here, we rewrite our sample application as a Model 2 application. You’ll
also learn how to leverage design patterns to improve the Model 2 application.
ABOUT THE BOOK xxiii
Part 2
Part 2 covers six web frameworks. In chapter 5, you’ll learn about Struts. We intro-
duce this framework in chapter 1, but here we “deconstruct” it and describe all
the important moving parts. Chapter 6 examines Tapestry, another Model 2–based
open-source framework. We show you how the Tapestry

API completely encapsu-
lates the web
APIs in Java. Chapter 7 takes a look at WebWork, another open-source
Model 2 framework. It includes some innovative ideas for passing just-in-time
information between the layers of Model 2.
Chapter 8 covers the only commercial framework in the book, InternetBeans
Express, which is the framework included with Borland’s JBuilder. It is a rapid
application development environment that lets you create web applications in
record time.
Chapter 9 examines Velocity, which can act as a replacement for
JSP and other
visual representation languages. Velocity is a popular open-source framework that
is very cohesive and single-purpose. In chapter 10, you’ll learn about Cocoon, an
open-source publishing framework that also includes capabilities as a Model 2
web framework.
Chapter 11 offers an evaluation of all six frameworks. It lays out the criteria we
used to judge them, and gives you the information you need to evaluate frame-
works on your own.
Part 3
Part 3 looks at best practices and helpful techniques for building web applications
in the real world. The topic coverage is very broad, but we focus on various tech-
niques and tools for building web applications.
Chapter 12 discusses techniques for separating concerns between the tiers of
the application. Chapter 13 describes user interface techniques for managing the
flow of information in web applications. It shows you how to build page-at-a-time
displays and sortable columns without sacrificing clean Model 2 architecture. We
also discuss building “undo” operations in web applications, using either transac-
tion processing or the Memento design pattern. Chapter 14 focuses on perfor-
mance. You’ll learn how to profile web applications to determine whether
performance bottlenecks exist, using both

SDK-supplied and commercial tools.
Next, we look at performance pitfalls and common mistakes and offer solutions.
Then we delve into object pooling and explain how to implement it using either
Java references or Jakarta Commons pooling.
Chapter 15 complements the previous chapter by showing you how to conserve
resources. We examine several sophisticated caching techniques using both the