Kenneth A. Kousen FOREWORD BY Guillaume Laforge M A N N I N G Making Java Groovy Making Java Groovy KENNETH A. KOUSEN MANNING SHELTER ISLAND For online information and ordering of this and other Manning books, please visit www.manning.com. The publisher offers discounts on this book when ordered in quantity. For more information, please contact Special Sales Department Manning Publications Co. 20 Baldwin Road PO Box 261 Shelter Island, NY 11964 Email: [email protected] ©2014 by Manning Publications Co. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by means electronic, mechanical, photocopying, or otherwise, without prior written permission of the publisher. Photographs in this book were created by Martin Evans and Jordan Hochenbaum, unless otherwise noted. Illustrations were created by Martin Evans, Joshua Noble, and Jordan Hochenbaum. Fritzing (fritzing.org) was used to create some of the circuit diagrams. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in the book, and Manning Publications was aware of a trademark claim, the designations have been printed in initial caps or all caps. Recognizing the importance of preserving what has been written, it is Manning’s policy to have the books we publish printed on acid-free paper, and we exert our best efforts to that end. Recognizing also our responsibility to conserve the resources of our planet, Manning books are printed on paper that is at least 15 percent recycled and processed without the use of elemental chlorine. Manning Publications Co. Development editor: Cynthia Kane 20 Baldwin Road Copyeditor: Melinda Rankin PO Box 261 Proofreader: Melody Dolab Shelter Island, NY 11964 Typesetter: Dennis Dalinnik Cover designer: Marija Tudor ISBN: 9781935182948 Printed in the United States of America 1 2 3 4 5 6 7 8 9 10 – MAL – 19 18 17 16 15 14 13 To my father, Morton Kousen, MD, who taught me everything I know about dedication, persistence, and facing the future with a positive and upbeat attitude, despite whatever pain and difficulties lay ahead. He will always be my best example of what a man should be. brief contents PART 1 UP TO SPEED WITH GROOVY. ........................................1 1 ■ Why add Groovy to Java? 3 2 ■ Groovy by example 18 3 ■ Code-level integration 46 4 ■ Using Groovy features in Java 64 PART 2 GROOVY TOOLS..........................................................91 5 ■ Build processes 93 6 ■ Testing Groovy and Java projects 126 PART 3 GROOVY IN THE REAL WORLD....................................165 7 ■ The Spring framework 167 8 ■ Database access 199 9 ■ RESTful web services 227 10 ■ Building and testing web applications 257 vii contents foreword xv preface xvii acknowledgments xix about this book xxii about the cover illustration xxvi PART 1 UP TO SPEED WITH GROOVY. ............................1 1 Why add Groovy to Java? 3 1.1 Issues with Java 4 Is static typing a bug or a feature? 5 ■ Methods must be in a class, even if you don’t need or want one 7 ■ Java is overly verbose 10 Groovy makes testing Java much easier 11 ■ Groovy tools simplify your build 13 1.2 Groovy features that help Java 14 1.3 Java use cases and how Groovy helps 15 Spring framework support for Groovy 16 ■ Simplified database access 16 ■ Building and accessing web services 16 Web application enhancements 17 1.4 Summary 17 ix