book

Harnessing Hibernate

by James Elliott, Timothy M. O'Brien, Ryan Fowler

April 2008

Intermediate to advanced

380 pages

11h 26m

English

O'Reilly Media, Inc.

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How to Use This BookFont ConventionsOn the Web SiteHow to Contact UsAcknowledgmentsJames ElliottRyan FowlerTimothy O’Brien
Getting an Ant DistributionWhy do I care?How do I do that?Check Your Java VersionWhat just happened?What about…Getting the Maven Tasks for AntHow do I do that?Installing the Maven Tasks for AntUsing the HSQLDB Database EngineWhy do I care?How do I do that?What about…Using Hibernate CoreHow do I do that?Setting Up a Project HierarchyWhy do I care?How do I do that?A quick testWhat just happened?What’s next?Why didn’t it work?
Writing a Mapping DocumentWhy do I care?How do I do that?Generating Some ClassHow do I do that?Cooking Up a SchemaHow do I do that?What just happened?What about…
Configuring HibernateCreating Persistent ObjectsHow do I do that?What just happened?What about…Finding Persistent ObjectsHow do I do that?What just happened?What about…Better Ways to Build QueriesWhy do I care?How do I do that?What about…
Mapping CollectionsHow do I do that?Why didn’t it work?What about…What just happened?Persisting CollectionsHow do I do that?What just happened?Retrieving CollectionsUsing Bidirectional AssociationsWorking with Simpler CollectionsHow do I do that?
Eager and Lazy AssociationsHow do I do that?What about…My head hurtsOrdered CollectionsHow do I do that?Augmenting Associations in CollectionsHow do I do that?What just happened?What about…Lifecycle AssociationsHow do I do that?Reflexive AssociationsHow do I do that?
Defining a User TypeHow do I do that?Defining a Persistent Enumerated TypeUsing a Custom Type MappingHow do I do that?What about…Working with Persistent EnumerationsHow do I do that?Not so fast!What just happened?Why didn’t it work?Building a Composite User TypeHow do I do that?What about…
Hibernate AnnotationsWhy do I care?How do I do that?Why do I have to?Annotating Model ObjectsHow do I do that?Annotating TrackAnnotating AlbumDoes it work?An Alternate ApproachWhat now?

Using Simple CriteriaHow do I do that?What about…Compounding CriteriaProjection and Aggregation with CriteriaHow do I do that?Applying Criteria to AssociationsHow do I do that?What just happened?Querying by ExampleHow do I do that?Property-Oriented Criteria FactoriesWhat about…
Writing HQL QueriesHow do I do that?What just happened?What about…Selecting Properties and PiecesHow do I do that?What about…SortingHow do I do that?Working with Aggregate ValuesHow do I do that?What just happened?Writing Native SQL QueriesHow do I do that?What about…
Setting Up a MySQL DatabaseHow do I do that?Connecting to MySQLTrying It OutWhat just happened?Looking at the DataWhat about…
Installing the Hibernate Tools in EclipseHow do I do that?What went wrong?Now what?Creating a Hibernate Console ConfigurationMore Editing SupportBut wait, there’s more!The Hibernate Console PerspectiveWhat about…Code GenerationMapping Diagrams
What Is Maven?Maven’s standard directory layoutInstalling MavenBuilding, Testing, and Running a ProjectGenerating IDE Project Files using MavenGenerating Reports with MavenA Maven Project Object ModelParent/child Project Object ModelsThe Maven Build LifecycleUsing the Maven Hibernate3 Plug-inConfiguring the Hibernate3 plug-inGenerating Hibernate mapping documentationBecoming a Maven Maven
What Is Spring?What is inversion of control?Combining Spring and HibernateAdding the Spring framework as a project dependencyWriting a Data Access ObjectWhat is a Data Access Object?Why would I want to use a DAO?Writing the ArtistDAO interfaceImplementing the ArtistDAO interfaceWhat HibernateDaoSupport providesHow do I do that?Where are the other DAOs?Creating an Application ContextHibernate configuration propertiesPutting It All TogetherTransactions: the test interfaceHow do I activate the transactional annotation?Adapting CreateTest, QueryTest, and AlbumTestTestRunner: loading a Spring ApplicationContextRunning CreateTest, QueryTest, and AlbumTestIt worked! Now what?
Earn Your StripesDispatcherServletStripesFilterActionBeansViewsPrepare TomcatCreate the Web ApplicationWhat just happened?Add StripesWrite up an ActionBeanWhat just happened?What’s next?Dealing with AssociationsInterceptors: a powerful way to extend stripes
Basic TypesCustom Value Types“Any” Type MappingsAll Types
The Criterion FactoryThe Projection FactoryThe Order FactoryThe Property Factory
Getting Fluent in the Local SQL
Using the Spring Framework’s Transactional AnnotationTransactional annotation attributesTransaction propagationTransaction isolationUsing a JTA Transaction Manager
Online ManualsBooksSource CodeDealing with Newer ReleasesGetting Involved

Content preview from Harnessing Hibernate

Chapter 8. Criteria Queries

Relational query languages like HQL (and SQL, on which HQL is based) are extremely flexible and powerful, but they take a long time to truly master. Many application developers get by with a rudimentary understanding, cribbing similar examples from past projects, and calling in database experts when they need to come up with something truly new, or to understand a particularly cryptic query expression.

It can also be awkward to mix a query language’s syntax with Java code. The section “Better Ways to Build Queries” in Chapter 3 showed how to at least keep the queries in a separate file so they can be seen and edited in one piece, free of Java string escape sequences and concatenation syntax. Even with that technique, though, the HQL isn’t parsed until the mapping document is loaded, which means that any syntax errors it might harbor won’t be caught until the application is running.

Hibernate offers an unusual solution to these problems in the form of criteria queries. They provide a way to create and connect simple Java objects that act as filters for picking your desired results. You can build up nested, structured expressions. The mechanism also allows you to supply example objects to show what you’re looking for, with control over which details matter and which properties to ignore.

As you’ll see, this can be quite convenient. To be fair, it has its own (very minor) disadvantages. Expanding long query expressions into a Java API makes them take up more ...