Jeff Friesen
Java XML and JSONDocument Processing for Java SE2nd ed.
Jeff Friesen
Dauphin, MB, Canada
ISBN 978-1-4842-4329-9e-ISBN 978-1-4842-4330-5
https://doi.org/10.1007/978-1-4842-4330-5
Library of Congress Control Number: 2018968598
© Jeff Friesen 2019
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To my parents.

Introduction

XML and (the more popular) JSON let you organize data in textual formats. This book introduces you to these technologies along with Java APIs for integrating them into your Java code. This book introduces you to XML and JSON as of Java 11.

Chapter 1 introduces XML, where you learn about basic language features (such as the XML declaration, elements and attributes, and namespaces). You also learn about well-formed XML documents and how to validate them via the Document Type Definition and XML Schema grammar languages.

Chapter 2 focuses on Java’s SAX API for parsing XML documents. You learn how to obtain a SAX 2 parser; you then tour XMLReader methods along with handler and entity resolver interfaces. Finally, you explore a demonstration of this API and learn how to create a custom entity resolver.

Chapter 3 addresses Java’s DOM API for parsing and creating XML documents. After discovering the various nodes that form a DOM document tree, you explore the DOM API, where you learn how to obtain a DOM parser/document builder and how to parse and create XML documents. You then explore the Java DOM APIs related to the Load and Save, and Traversal and Range specifications.

Chapter 4 places the spotlight on Java’s StAX API for parsing and creating XML documents. You learn how to use StAX to parse XML documents with stream-based and event-based readers and to create XML documents with stream-based and event-based writers.

Moving on, Chapter 5 presents Java’s XPath API for simplifying access to a DOM tree’s nodes. You receive a primer on the XPath language, learning about location path expressions and general expressions. You also explore advanced features starting with namespace contexts.

Chapter 6 completes my coverage of XML by targetting Java’s XSLT API. You learn about transformer factories and transformers, and much more. You also go beyond the XSLT 1.0 and XPath 1.0 APIs supported by Java.

Chapter 7 switches gears to JSON. You receive an introduction to JSON, take a tour of its syntax, explore a demonstration of JSON in a JavaScript context (because Java doesn’t yet officially support JSON), and learn how to validate JSON objects in the context of JSON Schema.

You’ll need to work with third-party libraries to parse and create JSON documents. Chapter 8 introduces you to the mJson library. After learning how to obtain and use mJson, you explore the Json class, which is the entry point for working with mJSon.

Google has released an even more powerful library for parsing and creating JSON documents. The Gson library is the focus of Chapter 9 . In this chapter, you learn how to parse JSON objects through deserialization, how to create JSON objects through serialization, and much more.

Chapter 10 focuses on the JsonPath API for performing XPath-like operations on JSON documents.

Chapter 11 introduces you to Jackson, a popular suite of APIs for parsing and creating JSON documents.

Chapter 12 introduces you to JSON-P, an Oracle API that was planned for inclusion in Java SE, but was made available to Java EE instead.

Each chapter ends with assorted exercises that are designed to help you master the content. Along with long answers and true/false questions, you are often confronted with programming exercises. Appendix A provides the answers and solutions.

Thanks for purchasing this book. I hope you find it helpful in understanding XML and JSON in a Java context.

Jeff Friesen (October 2018)

Note

You can download this book’s source code by pointing your web browser to www.apress.com/9781484243299 and clicking the Source Code tab followed by the Download Now link.

Acknowledgments

I thank Apress Acquisition Editor Jonathan Gennick and the Apress Editorial Board for giving me the opportunity to create this second edition. I also thank Editor Jill Balzano for guiding me through the book development process. Finally, I thank my technical reviewer and copy editor for catching mistakes and making the book look great.

Table of Contents

Part I: Exploring XML1
Chapter 1:​ Introducing XML 3
What Is XML?​ 3
Language Features Tour 5
XML Declaration 5
Elements and Attributes 7
Character References and CDATA Sections 10
Namespaces 12
Comments and Processing Instructions 17
Well-Formed Documents 17
Valid Documents 18
Document Type Definition 19
XML Schema 26
Summary 34
Chapter 2:​ Parsing XML Documents with SAX 35
What Is SAX?​ 35
Exploring the SAX API 36
Obtaining a SAX 2 Parser 36
Touring XMLReader Methods 37
Touring the Handler and Resolver Interfaces 42
Demonstrating the SAX API 47
Creating a Custom Entity Resolver 59
Summary 65
Chapter 3:​ Parsing and Creating XML Documents with DOM 67
What Is DOM?​ 67
A Tree of Nodes 68
Exploring the DOM API 71
Obtaining a DOM Parser/​Document Builder 71
Parsing and Creating XML Documents 73
Demonstrating the DOM API 77
Parsing an XML Document 77
Creating an XML Document 82
Working with Load and Save 85
Loading an XML Document into a DOM Tree 86
Configuring a Parser 90
Filtering an XML Document While Parsing 96
Saving a DOM Tree to an XML Document 100
Working with Traversal and Range 102
Performing Traversals 102
Performing Range Operations 107
Summary 111
Chapter 4:​ Parsing and Creating XML Documents with StAX 113
What Is StAX?​ 113
Exploring StAX 114
Parsing XML Documents 115
Creating XML Documents 125
Summary 138
Chapter 5:​ Selecting Nodes with XPath 139
What Is XPath?​ 139
XPath Language Primer 139
Location Path Expressions 140
General Expressions 143
XPath and DOM 145
Advanced XPath 154
Namespace Contexts 154
Extension Functions and Function Resolvers 156
Variables and Variable Resolvers 161
Summary 164
Chapter 6:​ Transforming XML Documents with XSLT 165
What Is XSLT?​ 165
Exploring the XSLT API 166
Demonstrating the XSLT API 170
Going Beyond XSLT 1.​0 and XPath 1.​0 179
Downloading and Testing SAXON-HE 9.​9 179
Playing with SAXON-HE 9.​9 180
Summary 183
Part II: Exploring JSON185
Chapter 7:​ Introducing JSON 187
What Is JSON?​ 187
JSON Syntax Tour 188
Demonstrating JSON with JavaScript 190
Validating JSON Objects 195
Summary 202
Chapter 8:​ Parsing and Creating JSON Objects with mJson 205
What Is mJson?​ 205
Obtaining and Using mJson 206
Exploring the Json Class 206
Creating Json Objects 207
Learning About Json Objects 213
Navigating Json Object Hierarchies 223
Modifying Json Objects 225
Validation 232
Customization via Factories 235
Summary 242
Chapter 9:​ Parsing and Creating JSON Objects with Gson 243
What Is Gson?​ 243
Obtaining and Using Gson 244
Exploring Gson 244
Introducing the Gson Class 245
Parsing JSON Objects Through Deserialization 248
Creating JSON Objects Through Serialization 258
Learning More About Gson 267
Summary 298
Chapter 10:​ Extracting JSON Values with JsonPath 299
What Is JsonPath?​ 299
Learning the JsonPath Language 300
Obtaining and Using the JsonPath Library 304
Exploring the JsonPath Library 306
Extracting Values from JSON Objects 306
Using Predicates to Filter Items 309
Summary 321
Chapter 11:​ Processing JSON with Jackson 323
What Is Jackson?​ 323
Obtaining and Using Jackson 324
Working with Jackson’s Basic Features 325
Streaming 325
Tree Model 334
Data Binding 340
Working with Jackson’s Advanced Features 350
Annotation Types 350
Custom Pretty Printers 390
Factory, Parser, and Generator Features 398
Summary 402
Chapter 12:​ Processing JSON with JSON-P 405
What Is JSON-P?​ 405
JSON-P 1.​0 405
JSON-P 1.​1 408
Obtaining and Using JSON-P 410
Working with JSON-P 1.​0 411
Working with the Object Model API 411
Working with the Streaming Model API 418
Working with JSON-P 1.​1’s Advanced Features 423
JSON Pointer 424
JSON Patch 431
JSON Merge Patch 440
Editing/​Transformation Operations 447
Java SE 8 Support 449
Summary 456
Part III: Appendixes459
Appendix A:​ Answers to Exercises 461
Chapter 1:​ Introducing XML 461
Chapter 2:​ Parsing XML Documents with SAX 466
Chapter 3:​ Parsing and Creating XML Documents with DOM 474
Chapter 4:​ Parsing and Creating XML Documents with StAX 486
Chapter 5:​ Selecting Nodes with XPath 493
Chapter 6:​ Transforming XML Documents with XSLT 497
Chapter 7:​ Introducing JSON 501
Chapter 8:​ Parsing and Creating JSON Objects with mJson 503
Chapter 9:​ Parsing and Creating JSON Objects with Gson 506
Chapter 10:​ Extracting JSON Values with JsonPath 510
Chapter 11:​ Processing JSON with Jackson 511
Chapter 12:​ Processing JSON with JSON-P 515
Index 519

About the Author and About the Technical Reviewer

About the Author

Jeff Friesen
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is a freelance teacher and software developer with an emphasis on Java. In addition to authoring Java I/O, NIO and NIO.2 (Apress), Java Threads and the Concurrency Utilities (Apress), and the first edition of this book, Jeff has written numerous articles on Java and other technologies (such as Android) for JavaWorld ( JavaWorld.com ), informIT ( InformIT.com ), Java.net , SitePoint ( SitePoint.com ), and other web sites. Jeff can be contacted via his web site at JavaJeff.ca or via his LinkedIn ( LinkedIn.com ) profile ( www.linkedin.com/in/javajeff ).

 

About the Technical Reviewer

Massimo Nardone
../images/394211_2_En_BookFrontmatter_Figc_HTML.jpg

has more than 24 years of experiences in Security, web/mobile development, Cloud, and IT architecture. His true IT passions are Security and Android.

He has been programming and teaching how to program with Android, Perl, PHP, Java, VB, Python, C/C++, and MySQL for more than 20 years.

He holds a Master of Science degree in Computing Science from the University of Salerno, Italy.

He has worked as a Project Manager, Software Engineer, Research Engineer, Chief Security Architect, Information Security Manager, PCI/SCADA Auditor, and Senior Lead IT Security/Cloud/SCADA Architect for many years.

His technical skills include Security, Android, Cloud, Java, MySQL, Drupal, Cobol, Perl, web and mobile development, MongoDB, D3, Joomla, Couchbase, C/C++, WebGL, Python, Pro Rails, Django CMS, Jekyll, Scratch, etc.

He worked as visiting lecturer and supervisor for exercises at the Networking Laboratory of the Helsinki University of Technology (Aalto University). He holds four international patents (PKI, SIP, SAML, and Proxy areas).

He currently works as Chief Information Security Officer (CISO) for Cargotec Oyj, and he is member of ISACA Finland Chapter Board.

Massimo has been reviewing more than 45 IT books for different publishing companies, and he is the coauthor of Pro Android Games (Apress, 2015), Pro JPA 2 in Java EE 8 (APress 2018), and Beginning EJB in Java EE 8 (Apress, 2018).

 
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