Core JSTL: mastering the JSP standard tag library

603 Pages·5.384 MB·English

by  Geary, David M

c o r e
JSTL
Mastering the JSP™
Standard Tag Library
DAVID M. GEARY
Prentice Hall PTR, Upper Saddle River, NJ 07458 Sun Microsystems Press
www.phptr.com A Prentice Hall Title
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Editorial/production supervision: Patti Guerrieri
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Sun Microsystems Press publisher: Michael Llwyd Alread
10 9 8 7 6 5 4 3 2 1
ISBN 0-13-100153-1
Sun Microsystems Press
A Prentice Hall Title

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PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . xviii
1
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . 2
JSTL Overview 5
What Is JSTL? 6
The JSTL Expression Language 7
The JSTL Tag Libraries 8
Getting Started 23
The JSTL Specification 23
The JSTL Reference Implementation 24
Downloading and Installing a Servlet Container 26
A Simple JSTL Web Application 30
JSTL Design Principles 34
Naming Conventions for JSTL Actions 35
Scoped Variables vs. Scripting Variables 35
vi Contents
Static vs. Dynamic Action Attributes 36
Error Handling 37
Configuration Settings 37
2
THE JSTL EXPRESSION LANGUAGE . . . . . . . . . . . . .38
Expression Language Overview 40
How the Expression Language Works 40
How to Use the Expression Language 41
Expressions 41
Identifiers 43
Operators 44
Operator Precedence 45
The . and [] Operators 45
Accessing JavaBeans Components 46
Accessing Objects Stored in Arrays, Lists, and Maps 52
A Closer Look at the [] Operator 56
The empty Operator 60
Type Coercion 62
Literal Values 63
Implicit Objects 64
Accessing Request Parameters 65
Accessing Request Headers 69
Accessing Context Initialization Parameters 72
Accessing Cookies 74
Accessing Scoped Attributes 78
Accessing JSP Page and Servlet Properties 80
Method Invocation 86
EL Expressions in Custom Actions 91
Common Mistakes 95
Forgetting Curly Braces 95
Forgetting taglib Declarations 96
Neglecting to Store Variables in a Scope 96
Using Illegal Characters for Attribute Values 97
Inadvertently Using Implicit Objects 98
Contents vii
3
GENERAL-PURPOSE
AND CONDITIONAL ACTIONS . . . . . . . . . . . . . . 100
General-Purpose Actions 102
The <c:out> Action 102
The <c:set> Action 111
The <c:remove> Action 125
The <c:catch> Action 126
Conditional Actions 127
Simple Conditions 128
Mutually Exclusive Conditions 132
Using Conditional and General-Purpose Actions Together 137
Conditional Custom Actions 145
4
ITERATION ACTIONS. . . . . . . . . . . . . . . . . . . . 150
The <c:forEach> Action 154
Iterating Over Integer Values 155
Iterating Over Data Structures 158
The <c:forTokens> Action 166
Iteration Status 171
Iteration Status for Integer Iterations 172
Iteration Status for Data Structure Iterations 174
Custom Iteration Actions 178
Collaboration Custom Actions 178
Iteration Custom Actions 182
5
URL ACTIONS . . . . . . . . . . . . . . . . . . . . . . . . 198
Overview 201
The <c:import> Action 201
The <c:redirect> Action 208
The <c:url> Action 208
The <c:param> Action 210
viii Contents
Accessing External Resources 210
Accessing Resources in Foreign Contexts 215
Redirecting a Response 225
6
CONFIGURATION SETTINGS . . . . . . . . . . . . . . . 230
Overview 232
The FMT_LOCALE Configuration Setting 235
Temporarily Overriding Configuration Settings 235
The Config Class 239
Accessing Configuration Settings in Servlets 240
Accessing Configuration Settings in Life-Cycle Listeners 242
Accessing Configuration Settings in Custom Actions 243
7
I18N ACTIONS . . . . . . . . . . . . . . . . . . . . . . . 248
Overview 250
Localizing Messages 251
Multiple Resource Bundles 254
Compound Messages 255
I18N and L10N 258
Locales 258
Resource Bundles 259
Unicode and Charsets 260
Localization Contexts 263
An Overview of the I18N Actions 264
Use of <fmt:message> 265
Localization Context Lookup 268
Resource Bundle Lookup 274
An Example of Dynamically Switching Locales 278
Compound Messages and <fmt:param> 283
Request Encoding 287
I18N Custom Actions 293
Validation with JSP Pages 296
Validation with a Custom Action That Uses
javax.servlet.jsp.jstl.fmt.LocaleSupport 304
Contents ix
8
FORMATTING ACTIONS . . . . . . . . . . . . . . . . . . 308
Formatting and Parsing Numbers 310
Custom Number Patterns 319
Percents 325
Currencies 326
Formatting and Parsing Dates and Times 333
Custom Patterns for Dates and Times 336
Using Time Zones 343
Determining a Formatting Locale 352
Formatting Locale Lookup 354
9
DATABASE ACTIONS . . . . . . . . . . . . . . . . . . . . 356
Overview 358
SQL Actions 358
Configuration Settings 359
A Simple Database 360
How JSTL Locates Data Sources 363
Creating Data Sources 365
Specify Your Data Source in the Deployment Descriptor 366
Specify Your Data Source with <sql:setDataSource> 369
Create Your Data Source in a Business Component 372
Querying a Database 378
Using <sql:query> 378
Accessing Query Properties 382
Scrolling Through Large Queries 385
Prepared Statements and SQL Parameters 389
Updating a Database 398
Database Inserts 399
Database Updates 400
Database Deletes 407
Executing Database Transactions 411
Implementing Database Custom Actions 418