Building Spring 2 Enterprise Applications

Transcription

1 Building Spring 2 Enterprise Applications Interface 21 with Bram Smeets and Seth Ladd

2 Building Spring 2 Enterprise Applications Copyright 2007 by Interface 21, Bram Smeets, Seth Ladd All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of the copyright owner and the publisher. ISBN-13 (pbk): ISBN-10 (pbk): Printed and bound in the United States of America Trademarked names may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, we use the names only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. Java and all Java-based marks are trademarks or registered trademarks of Sun Microsystems, Inc., in the US and other countries. Apress, Inc., is not affiliated with Sun Microsystems, Inc., and this book was written without endorsement from Sun Microsystems, Inc. Lead Editors: Matthew Moodie, Steve Anglin Technical Reviewer: Rob Harrop Editorial Board: Steve Anglin, Ewan Buckingham, Gary Cornell, Jonathan Gennick, Jason Gilmore, Jonathan Hassell, Chris Mills, Matthew Moodie, Jeffrey Pepper, Ben Renow-Clarke, Dominic Shakeshaft, Matt Wade, Tom Welsh Project Manager: Kylie Johnston Copy Edit Manager: Nicole Flores Copy Editor: Marilyn Smith Assistant Production Director: Kari Brooks-Copony Production Editor: Laura Cheu Compositors: Dina Quan, Linda Weidemann Proofreader: April Eddy Indexer: Becky Hornyak Artist: Kinetic Publishing Services, LLC Cover Designer: Kurt Krames Manufacturing Director: Tom Debolski Distributed to the book trade worldwide by Springer-Verlag New York, Inc., 233 Spring Street, 6th Floor, New York, NY Phone SPRINGER, fax , orders-ny@springer-sbm.com, or visit For information on translations, please contact Apress directly at 2855 Telegraph Avenue, Suite 600, Berkeley, CA Phone , fax , info@apress.com, or visit The information in this book is distributed on an as is basis, without warranty. Although every precaution has been taken in the preparation of this work, neither the author(s) nor Apress shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the information contained in this work. The source code for this book is available to readers at in the Source Code/ Download section.

3 Contents at a Glance Introduction xi CHAPTER 1 A Gentle Introduction to the Spring Framework CHAPTER 2 The Core Container CHAPTER 3 Aspect-Oriented Programming CHAPTER 4 Spring AOP CHAPTER 5 Introduction to Data Access CHAPTER 6 Persistence with JDBC CHAPTER 7 Transaction Management CHAPTER 8 Spring MVC CHAPTER 9 View Technologies CHAPTER 10 Testing APPENDIX Installing the Eclipse Web Tools Platform INDEX iii

4 Contents Introduction xi CHAPTER 1 A Gentle Introduction to the Spring Framework Building a Business Application Java Platform Hurdles Enter the Spring Framework Introducing the Spring Framework Modules Introducing the Sample Application Managing Dependencies in Applications A Use Case That Has Dependencies Dealing with the Dependencies in Plain Java Looking Up Dependencies with JNDI Using the Spring Framework to Provide Dependencies Integrating the Spring Framework with Java EE Spring Framework Integration with Java EE Technologies Spring and EJB Setting Up the Spring Framework in Your Applications Summary CHAPTER 2 The Core Container How Do Factories Work? Factory Methods Factory Objects Introducing the BeanFactory Creating a BeanFactory Object Using Dependency Lookup Using Dependency Injection Using XML Tags for Bean Configuration Examining the Bean Life Cycle Bean Scope: Singleton or Prototype Bean Initialization Bean Destruction Using Factory Methods and Factory Objects in the Container Implementing Factory Methods Implementing Factory Objects Implementing Factory Objects with the FactoryBean Interface v

5 vi CONTENTS Introducing the ApplicationContext Representing Resources Creating ApplicationContext Objects Configuring the Container with Spring 2.0 XML Tags Using the Container As a Deployment Model Summary CHAPTER 3 Aspect-Oriented Programming Extending Applications the Traditional Way Extending a Base Class Using the Observer Design Pattern Using the Decorator Design Pattern Benefits of Separating Concerns Limitations of Object-Oriented Solutions Enter AOP The Classic Spring AOP Framework Implementing Cross-Cutting Concerns Configuring AOP in the Spring Container Using Proxy Objects Filtering Methods Selecting Advice Types AOP Usage in the Spring Framework Other Advice Classes Logging Messages with Around Advice Debugging with Around Advice Limiting Concurrent Method Execution with Around Advice Summary CHAPTER 4 Spring AOP Introducing AspectJ and Aspects Join Points and Pointcuts in AspectJ AspectJ Aspect Creation Aspects in Spring A Aspect Advice Types Pointcut Declaration and Reuse Auto-Proxy Creation in the Spring Container Advice and Aspect Ordering

6 CONTENTS vii Using AOP XML Tags AOP Configuration Tags XML Aspect Configuration Pointcut Declaration and Reuse with XML Advice Declaration in XML Advice Ordering in XML Advisors with AspectJ Pointcuts Proxy Type Selection in XML Working with Pointcuts Selecting Methods Directly Selecting Methods via Classes, Packages, and Inheritance Selecting Methods via Annotations Binding Advice Arguments Binding Method Argument Values Binding Return Values Binding Exceptions Binding Annotations Summary CHAPTER 5 Introduction to Data Access Spring Integration with Data-Access Frameworks The Challenges of Data Access Effects of Data-Access Leakage Database Resources Exceptions Related to Data Access Database Transactions Abstractions The Spring Solutions to Data Access Managing Database Resources Handling Data-Access Exceptions Working with Database Transactions Data-Access Leakage Changing the Application Abstractions for Data-Access Code Using the Repository Adapter The DataSource Interface and Connection Pools Setting Up Connection Pools Using Value Placeholders and Property Files Summary

7 viii CONTENTS CHAPTER 6 Persistence with JDBC Defining the Data Layer Using the JdbcTemplate Class Using the JdbcDaoSupport Class Working with Database Data Using Callbacks Using the RowMapper Interface Using the PreparedStatementSetter Interface Using Executable Query Objects Using the MappingSqlQuery Class Using the SqlUpdate Class Using the StoredProcedure Class Creating Batches Working with LOBs Using the NativeJdbcExtractor Interface Introducing New Spring 2.0 Features Using the SimpleJdbcTemplate Class Performing JNDI Data Source Lookups Summary CHAPTER 7 Transaction Management Database Transactions Transaction Management in Spring Configuring Spring s Transaction Manager for JDBC Configuring Spring s Transaction Manager for JTA Transaction Demarcation in Spring Transaction Demarcation Introduced in Spring Transaction Demarcation Introduced in Spring Transaction Demarcation Introduced in Spring Summary CHAPTER 8 Spring MVC Web Application Architecture The Domain Model The Data-Access Layer Web Request Routing User Interface Spring MVC Architecture MVC Components DispatcherServlet and Request Handling

8 CONTENTS ix Spring MVC Configuration Writing web.xml Creating ApplicationContexts Reviewing the Web Application Startup Process A Sample Spring MVC Application Configuring the Sample Application Implementing the List All Members Use Case Implementing the Search for a Member Use Case Implementing the Register a New Member Use Case Reviewing the Sample Application Implementation Summary CHAPTER 9 View Technologies Choosing a View Technology Using View Resolvers Using General-Purpose View Resolvers Combining View Resolvers Using View Technologies JSP Velocity FreeMarker XSLT PDF Excel JasperReports Introducing New Spring 2.0 Form Tags Summary CHAPTER 10 Testing Introducing Testing Approaches Unit Testing Integration Testing Test-Driven Development Writing Unit Tests Using JUnit Establishing the Requirements Writing the Test Definining a Test Suite Creating Mock Implementations with EasyMock Defining and Implementing the Interface Creating a Mock Object Testing with EasyMock

9 x CONTENTS Using Spring Support for Integration Testing Testing Without Transactions Testing with Transactions Testing with a DataSource Using Spring Mock Classes Summary APPENDIX Installing the Eclipse Web Tools Platform Installing Tomcat Installing Eclipse Installing WTP Starting a New Web Project INDEX

10 Introduction This book covers the Spring Framework, the Java application framework of choice for tens of thousands of Java developers worldwide. We feel it is important to introduce you to the Spring Framework by showing you how to use it. So we wrote a book that uses a complex sample application to demonstrate how the Spring Framework is used in a typical business application. By exploring the code from the sample application, presented throughout this book, you will benefit from many insights in application development. This is important knowledge for any developer, no matter how many years of experience you have. Ultimately, the goal of this book is to make you, the reader, more efficient as a Java developer by taking the things that are good about the Java platform and using them in the most efficient and reliable way. In this book, we focus on how to be successful in two areas that are important in software development: simplicity and consistency. Both goals can be achieved with the Spring Framework, although creating a simple design requires effort from your side as well. The concept of API consistency involves applying the same design and coding pattern where applicable. Clients of a consistent API feel at home when using it, and are able to concentrate on its logic instead of its semantics. The Spring Framework excels at bringing consistency to the Java platform. We re going to show you how to leverage this consistency to make your applications more consistent. Simplicity in software development means four things: To implement only the functionality that is absolutely required and nothing more To write code that is as clean, readable, and simple as possible To write code that is easy to test and is tested only once To streamline the development process cycle to be as agile and rapid as possible (taking into account the settings of your projects) The Spring Framework enables you to implement your applications in a simple way, but it does not stop you from writing overly complex software that is hard to test and doesn t deliver what is expected. This book will guide you in achieving simplicity in your code and show you how the Spring Framework helps to write simple code that is easy to test. Who This Book Is For This book is intended for Java developers who want to use the Spring Framework in their applications. You will learn not only what features the Spring Framework offers, but also when to use them and how to use them correctly. xi

11 xii INTRODUCTION How This Book Is Structured This book is divided into ten chapters: Chapter 1 introduces the Spring Framework and its core values. In this chapter, we will discuss the modules of the Spring Framework, introduce the sample application, and use the Spring Framework to solve an important problem that many applications face. This chapter also examines Spring s relationship with Java Enterprise Edition and Enterprise JavaBeans. Chapter 2 details the core deployment model of the Spring Framework that you can use to configure and deploy your applications. It s the perfect start to bring consistency to your applications. Once you know how this deployment model works, you can reuse it every time you need to configure objects. Chapter 3 explains how to reuse the most efficient and flexible solution to a problem everywhere you need it. The technical term for a solution that is required in multiple places is a cross-cutting concern. This chapter introduces Spring s aspect-oriented programming (AOP) framework. Chapter 4 builds on the theme of AOP and shows how Spring 2.0 makes AOP more consistent and simpler to use. Chapter 5 describes how data access also called persistence is simplified and made consistent by the Spring Framework. If you handle data access correctly, it will improve the simplicity of your applications significantly, and Chapter 5 explains how to do that. Chapter 6 discusses the data-access layer of the sample application, which is implemented using Spring s JDBC framework. Chapter 7 shows you how to move transaction management out of your application code by using Spring s transaction management framework. Chapter 8 introduces Spring s web framework and discusses how the web layer of the sample application is implemented. Chapter 9 demonstrates different ways of returning content to the browser window. This chapter also explores how to create and return Adobe PDF and Microsoft Excel files to the browser with ease. Chapter 10 shows you how to do less work during development projects by testing applications before you write code. In economics, the standard way to reduce costs is to do less work and deliver to customers only what they really want, and nothing more. This chapter translates this principle to application development. This book shows how the Spring Framework can make you more efficient as a developer and as a team member. The final chapter brings everything together and explains how you can start changing your development process so that you not only develop more efficient code, but also shorten the development life cycle. Prerequisites We assume that you have a good understanding of the Java programming language, preferably version 1.4 or later. For the first four chapters of this book and in Chapter 10, you are expected to understand classes, objects, inheritance, exception handling, and threads in Java. For Chapters 5 to 7, you are expected to have a basic understanding of JDBC, relational databases, the SQL query language, and database transactions.

12 INTRODUCTION xiii For Chapter 8, you are expected to have a basic understanding of HTML, JSP, and servlet containers such as Tomcat. Chapter 9 discusses specific frameworks with which the Spring Framework integrates. If you are not familiar with any of these frameworks, but wish to use them, you are encouraged to first gain a basic understanding of how they work, and then return to this chapter to learn how to use them in combination with the Spring Framework. Downloading the Code The source code for this book is available to readers from the Apress website ( com), in the Source Code/Download section. Please feel free to visit the Apress website and download all the code there. You can also check for errata and find related titles from Apress.