THE EXPERT’S VOICE® IN JAVA Java XML JSON and — Jeff Friesen Java XML and JSON Jeff Friesen Java XML and JSON Jeff Friesen Dauphin, Manitoba, Canada ISBN-13 (pbk): 978-1-4842-1915-7 ISBN-13 (electronic): 978-1-4842-1916-4 DOI 10.1007/978-1-4842-1916-4 Library of Congress Control Number: 2016943840 Copyright © 2016 by Jeff Friesen This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. 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Contents at a Glance About the Author ............................................................................xiii About the Technical Reviewer ..........................................................xv Acknowledgments ..........................................................................xvii Introduction .....................................................................................xix ■ Chapter 1: Introducing XML ............................................................1 ■ Chapter 2: Parsing XML Documents with SAX ..............................29 ■ Chapter 3: Parsing and Creating XML Documents with DOM .......57 ■ Chapter 4: Parsing and Creating XML Documents with StAX .......75 ■ Chapter 5: Selecting Nodes with XPath ........................................97 ■ Chapter 6: Transforming XML Documents with XSLT .................119 ■ Chapter 7: Introducing JSON ......................................................133 ■ Chapter 8: Parsing and Creating JSON Objects with mJson ..........149 ■ Chapter 9: Parsing and Creating JSON Objects with Gson .........179 v vi Contents at a Glance ■ Chapter 10: Extracting JSON Values with JsonPath ...................223 ■ Appendix A: Answers to Exercises ............................................241 Index ..............................................................................................279 Contents About the Author ............................................................................xiii About the Technical Reviewer ..........................................................xv Acknowledgments ..........................................................................xvii Introduction .....................................................................................xix ■ Chapter 1: Introducing XML ............................................................1 What Is XML? ..........................................................................................1 Language Features Tour ..........................................................................3 XML Declaration .......................................................................................................3 Elements and Attributes ...........................................................................................5 Character References and CDATA Sections ..............................................................7 Namespaces .............................................................................................................8 Comments and Processing Instructions .................................................................13 Well-Formed Documents .......................................................................14 Valid Documents ...................................................................................15 Document Type Defi nition .......................................................................................15 XML Schema ...........................................................................................................21 Summary ...............................................................................................28 vii viii Contents ■ Chapter 2: Parsing XML Documents with SAX ..............................29 What Is SAX? .........................................................................................29 Exploring the SAX API ............................................................................30 Obtaining a SAX 2 Parser ........................................................................................30 Touring XMLReader Methods ..................................................................................31 Touring the Handler and Resolver Interfaces..........................................................35 Demonstrating the SAX API ...................................................................40 Creating a Custom Entity Resolver ........................................................49 Summary ...............................................................................................54 ■ Chapter 3: Parsing and Creating XML Documents with DOM .......57 What Is DOM? ........................................................................................57 A Tree of Nodes .....................................................................................58 Exploring the DOM API ...........................................................................61 Obtaining a DOM Parser/Document Builder............................................................61 Parsing and Creating XML Documents ...................................................................63 Demonstrating the DOM API ..................................................................67 Summary ...............................................................................................74 ■ Chapter 4: Parsing and Creating XML Documents with StAX .......75 What Is StAX? ........................................................................................75 Exploring StAX .......................................................................................76 Parsing XML Documents.........................................................................................77 Creating XML Documents .......................................................................................85 Summary ...............................................................................................95 ■ Chapter 5: Selecting Nodes with XPath ........................................97 What Is XPath? ......................................................................................97 XPath Language Primer .........................................................................97 Location Path Expressions ......................................................................................98 General Expressions .............................................................................................101 Contents ix XPath and DOM ...................................................................................103 Advanced XPath ..................................................................................110 Namespace Contexts ............................................................................................110 Extension Functions and Function Resolvers .......................................................111 Variables and Variable Resolvers ..........................................................................115 Summary .............................................................................................118 ■ Chapter 6: Transforming XML Documents with XSLT .................119 What Is XSLT? ......................................................................................119 Exploring the XSLT API .........................................................................120 Demonstrating the XSLT API ................................................................123 Summary .............................................................................................132 ■ Chapter 7: Introducing JSON ......................................................133 What Is JSON? .....................................................................................133 JSON Syntax Tour ................................................................................134 Demonstrating JSON with JavaScript .................................................137 Validating JSON Objects ......................................................................140 Summary .............................................................................................147 ■ Chapter 8: Parsing and Creating JSON Objects with mJson ..........149 What Is mJson? ...................................................................................149 Obtaining and Using mJson ..................................................................................150 Exploring the Json Class .....................................................................150 Creating Json Objects ...........................................................................................151 Learning About Json Objects ................................................................................155 Navigating Json Object Hierarchies ......................................................................163 Modifying Json Objects ........................................................................................165 Validation ..............................................................................................................170 Customization via Factories .................................................................................173 Summary .............................................................................................178