- •brief contents
- •contents
- •foreword
- •preface
- •acknowledgments
- •about this book
- •Roadmap
- •Code conventions and downloads
- •Author Online
- •About the author
- •about the cover illustration
- •1 Why add Groovy to Java?
- •1.1 Issues with Java
- •1.1.1 Is static typing a bug or a feature?
- •1.1.2 Methods must be in a class, even if you don’t need or want one
- •1.1.3 Java is overly verbose
- •1.1.4 Groovy makes testing Java much easier
- •1.1.5 Groovy tools simplify your build
- •1.2 Groovy features that help Java
- •1.3 Java use cases and how Groovy helps
- •1.3.1 Spring framework support for Groovy
- •1.3.2 Simplified database access
- •1.3.3 Building and accessing web services
- •1.3.4 Web application enhancements
- •1.4 Summary
- •2 Groovy by example
- •2.1 Hello, Groovy
- •2.2 Accessing Google Chart Tools
- •2.2.1 Assembling the URL with query string
- •2.2.2 Transmitting the URL
- •2.2.3 Creating a UI with SwingBuilder
- •2.3 Groovy Baseball
- •2.3.1 Database data and Plain Old Groovy Objects
- •2.3.2 Parsing XML
- •2.3.3 HTML builders and groovlets
- •2.4 Summary
- •3 Code-level integration
- •3.1 Integrating Java with other languages
- •3.2 Executing Groovy scripts from Java
- •3.2.1 Using JSR223 scripting for the Java Platform API
- •3.2.2 Working with the Groovy Eval class
- •3.2.3 Working with the GroovyShell class
- •3.2.4 Calling Groovy from Java the easy way
- •3.2.5 Calling Java from Groovy
- •3.3 Summary
- •4 Using Groovy features in Java
- •4.1 Treating POJOs like POGOs
- •4.2 Implementing operator overloading in Java
- •4.3 Making Java library classes better: the Groovy JDK
- •4.4 Cool AST transformations
- •4.4.1 Delegating to contained objects
- •4.4.2 Creating immutable objects
- •4.4.3 Creating singletons
- •4.5 Working with XML
- •4.6 Working with JSON data
- •4.7 Summary
- •5 Build processes
- •5.1 The build challenge
- •5.2 The Java approach, part 1: Ant
- •5.3 Making Ant Groovy
- •5.3.1 The <groovy> Ant task
- •5.3.2 The <groovyc> Ant task
- •5.3.3 Writing your build in Groovy with AntBuilder
- •5.3.4 Custom build scripts with Gant
- •5.3.5 Ant summary
- •5.4 The Java approach, part 2: Maven
- •5.4.2 The GMaven project
- •5.4.3 Maven summary
- •5.5 Grapes and @Grab
- •5.6 The Gradle build system
- •5.6.1 Basic Gradle builds
- •5.6.2 Interesting configurations
- •5.7 Summary
- •6 Testing Groovy and Java projects
- •6.1 Working with JUnit
- •6.1.1 A Java test for the Groovy implementation
- •6.1.2 A Groovy test for the Java implementation
- •6.1.3 A GroovyTestCase test for a Java implementation
- •6.2 Testing scripts written in Groovy
- •6.2.1 Useful subclasses of GroovyTestCase: GroovyShellTestCase
- •6.2.2 Useful subclasses of GroovyTestCase: GroovyLogTestCase
- •6.3 Testing classes in isolation
- •6.3.1 Coerced closures
- •6.3.2 The Expando class
- •6.3.3 StubFor and MockFor
- •6.4 The future of testing: Spock
- •6.4.1 The Search for Spock
- •6.4.2 Test well, and prosper
- •6.4.4 The trouble with tribbles
- •6.4.5 Other Spock capabilities
- •6.5 Summary
- •7 The Spring framework
- •7.1 A Spring application
- •7.2 Refreshable beans
- •7.3 Spring AOP with Groovy beans
- •7.4 Inline scripted beans
- •7.5 Groovy with JavaConfig
- •7.6 Building beans with the Grails BeanBuilder
- •7.7 Summary
- •8 Database access
- •8.1 The Java approach, part 1: JDBC
- •8.2 The Groovy approach, part 1: groovy.sql.Sql
- •8.3 The Java approach, part 2: Hibernate and JPA
- •8.4 The Groovy approach, part 2: Groovy and GORM
- •8.4.1 Groovy simplifications
- •8.5 Groovy and NoSQL databases
- •8.5.1 Populating Groovy vampires
- •8.5.2 Querying and mapping MongoDB data
- •8.6 Summary
- •9 RESTful web services
- •9.1 The REST architecture
- •9.3 Implementing JAX-RS with Groovy
- •9.4 RESTful Clients
- •9.5 Hypermedia
- •9.5.1 A simple example: Rotten Tomatoes
- •9.5.2 Adding transitional links
- •9.5.3 Adding structural links
- •9.5.4 Using a JsonBuilder to control the output
- •9.6 Other Groovy approaches
- •9.6.1 Groovlets
- •9.6.2 Ratpack
- •9.6.3 Grails and REST
- •9.7 Summary
- •10 Building and testing web applications
- •10.1 Groovy servlets and ServletCategory
- •10.2 Easy server-side development with groovlets
- •10.2.1 A “Hello, World!” groovlet
- •10.2.2 Implicit variables in groovlets
- •10.3.2 Integration testing with Gradle
- •10.3.3 Automating Jetty in the Gradle build
- •10.4 Grails: the Groovy “killer app”
- •10.4.1 The quest for the holy Grails
- •10.5 Summary
- •A.1 Installing a JDK
- •A.2 Installing Groovy
- •A.3 Testing your installation
- •A.4 IDE support
- •A.5 Installing other projects in the Groovy ecosystem
- •B.1 Scripts and the traditional example
- •B.2 Variables, numbers, and strings
- •B.2.1 Numbers
- •B.2.2 Strings and Groovy strings
- •B.3 Plain Old Groovy Objects
- •B.4 Collections
- •B.4.1 Ranges
- •B.4.2 Lists
- •B.4.3 Maps
- •B.5 Closures
- •B.6 Loops and conditionals
- •B.6.1 Loops
- •B.6.2 Conditionals
- •B.6.3 Elvis
- •B.6.4 Safe de-reference
- •B.7 File I/O
- •B.8.1 Parsing and slurping XML
- •B.8.2 Generating XML
- •B.8.3 Validation
- •B.9 JSON support
- •B.9.1 Slurping JSON
- •B.9.2 Building JSON
- •index
- •Symbols
226 |
CHAPTER 8 Database access |
It’s hard to be much simpler than that. Working with MongoDB20 is just as easy as using a traditional relational database.21
8.6Summary
Virtually every significant application requires persistent data. The vast majority of those are based on relational databases. In the Java world, relational persistence uses either JDBC or an object-relational mapping tool like Hibernate or JPA. This chapter reviewed both approaches and examined how Groovy can simplify them.
The Groovy Sql class removes most of the clutter that accompanies raw JDBC. Any code that uses JDBC directly can be significantly simplified using the Sql class.
Many modern applications use JPA for persistence, especially with Hibernate as the underlying API and the Spring framework to handle singletons and transactions. Just configuring such an application is a nontrivial task. On the other hand, the Grails framework handles all of it elegantly and with a minimum of effort.
Finally, many so-called NoSQL databases have a Java API. Some, like MongoDB, include a Groovy wrapper that makes working with the underlying databases simple.
20A detailed treatment of MongoDB is contained in the book MongoDB in Action (Manning, 2011) by Kyle Banker: www.manning.com/banker/.
21For some reason, none of the Twilight movies were returned from the “vampire” query. I thought about fixing that, and ultimately decided it wasn’t a bug, but a feature.
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