Hibernate in Action CHRISTIAN BAUER GAVIN KING MANNING. Greenwich (74" w. long.)

Size: px

Start display at page:

Download "Hibernate in Action CHRISTIAN BAUER GAVIN KING MANNING. Greenwich (74" w. long.)"

Ella Goodwin
6 years ago
Views:

1 Hibernate in Action CHRISTIAN BAUER GAVIN KING M MANNING Greenwich (74" w. long.)

2 foreword xi preface xiii ncknowledgrnents xu about this book xvi about Hibernate3 and EJB 3 xx nuthor online xxi about the title and cower xxii Understanding objec/relational persistente What is persistence! 3 contents Relational datnbases 3. Understanding SQL 4. Using SQL in Java 5. Persistence in object-orientpd applications The paradigm mismatch 7 The Problem of panularity 9 The Problem of subtypes 10 Theprohlem of identity 11 9 Problems relating to assoczations 13 The Problem of object graph navigation 14 9 The cost of the mismatch Persistence layers and alternatives 16 Layered architecture 17 Hand-coding a pprsistence layer with SQL/JDBC 18 Using serializatzon 19 9 Considm'ng EJB entity beans 20 Object-omented database Systems 21 Other Options Object/relational mapping 22 What is ORM? 23. Generic ORMproblems 25 WhyORM? Summary 29 V

3 vi 1 CONTENTS 5 Introducing und integrating Hibermate "Hello World" with Hibernate Understanding the architecture 36 lhe core interfaces 38 Callback interfaces 40 Typs 40 9 Extensaon interfaces Basic configuration 41 Crmtzng a SessionFacto?y non-managed environments 42 9 Configurataon in 45 9 Confpration an managed enuironments Advanced configuration Settings 51 Usang XML-based conf-urataon 51 9 PI-bound SessaonFactory 53 9 Logeng 54 Java Management Extennons (JMX) Summary 58 Mappingpersistent classes The CaveatEmptor application 60 Analyzang the business domain 61 lhe CaueatEmptor domaan model Implementing the domain model 64 Addressing leakage of concms 64. Transparent and automated persistence 65 9 Wmting POJOs 67 Implementang POJO associations 69. Addang logc to accessor methods Defining the mapping metadata 75 Metadata an XML 75 Basic property and class mappings 78 9 Attmbute-omented programming 84 Manipulating metadata at mntime Understanding object identity 87 Identaty uersus pquality 87 Hibmate 88.. Database identity with Choosingprimaly keys Fine-grained object models 92 Entity und ualue types 93. Usang components Mapping class inheritance 97 Table Per concrete dass 97 Table Per dass hierarchy 99 Tableper subclass 101 Choosing a strategy 104

4 CONTENTS I vii 3.7 Introducing associations 105 Managed associations? Multiplicity 106 The simplest possible association Making the association bidirectional A parent/child relationship Summary 112 Working with persistent objects The persistence lifecycle 115 Transient objects Persistent objects 117 Detached objects 118 The scope of object identity Outszde the zdentaty scope Implemmting equal() and hashcode() The persistence manager 126 Making an object persistent 126 Updating the Persistent state of a detached anstanre Retrieving a persastent object 129 Updatang a persistent object Makzng a persastmt object transaent Making a detached object transient Using transitive persistence in Hibernate 131 Perszstence by reachability 131 Cascading persastence wath Habernate Managzng auctaon categories 134 Dzstanpishang between transient and detached instances Retrieving objects 139 Retrieving objects by identifier 140 Introducing HQL 141 Quq by criteria 142. Quq by example 143 Fetching strategies Selectzng a fetching strategy in mappings 146 Tunzng object retneval Summary 152 Transactions, concurrency, und caching Transactions, concurrency, and caching Understanding database transactions 156 J9BC andpa transactions 157 API Flushing the Session The Habernate Transaction Understanding isolation levpls Choosing an isolation level Setting an asolation hel Using pessimistic locking Working with application transactions 168 Using managed uersionzng 169 Granularity of a Sesszon 172 Other ways to implernent optamistac locking 174

5 viii 1 CONTENTS 5.4 Caching theory and practice 175 Caching strategies and scopes 176 m The Hibernate cache architecture Caching in practice Summary 194 Aduanced mapping concepts Understanding the Hibernate type system 196 Built-in mapping types 198 Using mapping types Mapping collections of value types 211 Sets, bugs, lists, and maps Mapping entity associations 220 One-to-one associations Many-to-many associations Mapping polymorphic associations 234 Polymorphie many-to-one associations 234 Polymorphie collections Polymorphie associations and table;berconcrete-dass Summary 239 ReCmeving Executing queries 243 The quq antofaces 243 = Bindingparameters 245 Using named queries Basic queries for objects 250 The simplest query 250. Using aliases 251 Polymorphie queries Restriction 252. Comparison Operators 253 String matching Lopcal Operators 256. Ordering quq results Joining associations 258 Hibmate join Options 259 = Fetching associations 260 Using aliases with joins Using implicitjoins 265 Theta-style joins Comparing identijiers Writing report queries 269 Projection Using aggregation 272 Grouping 273 Restricting groups with hauing Improving performance with report queries 275

6 CONTENTS 1 ix 7.5 Advanced query techniques 276 Dynarnic quem'es Collectionfilters 279 Subqueries 281 Native SQL qum'es Optimizing object retrieval 286 Solving the n+l sekcts problern Using iterate() qum'es 289 = Cachingqueries Summary 292 Writing Hibernate applications Designing layered applications 295 Using Habernute in a smlet Pngzne 296 Using Hibernate in an EJB Container Implementing application transactions 320 Approvzng a nau auctzon Doang at the hard way 322 Using detnched perszstent objects Usang a longsession 325 Choosing an approach to application transartaons Handling Special kinds of data 330 Lpgacy schernas and cornposate keys 330. Audit logging Summary 347 Using the toolset Development processes 349 Top down Bottorn up 350. Middle out (rnetadata oriented) Meet in the rnaddle 350 Roundtrippang Automatic Schema generation 351 Prepanng the rnappzng rnetadata Creating the scherna Updatzng the scherna Generating POJO Code 358 Adding rneta-attributes 358 Generatang finders 360 Configunng hbrn2java 362 Running hbrn2~ava Existing Schemas and Middlegen 364 Starting Mzddlpgen Rertricting tables and relationshaps Custornizing the rnptadata generation 368 Generatang hbrn2~ava and XDoclet rnetadata 370

7 9.5 XDoclet 372 Setting value type attributes 372 Mapping entity associations Running XDoclet Summary 376 appendix A: SQLJundamentals 378 appendix B: ORM implementation strategies 382 B.l Properties or fields? 383 B.2 Dirty-checking strategies 384 appendix C: Back in the real world 388 C.1 The Strange copy 389 C.2 The more the better 390 C.3 We don t need primary keys 390 C.4 Time isn t linear 391 C.5 Dynamically unsafe 391 C.6 To synchronize or not? 392 C.7 Really fat client 393 C.8 Resuming Hibernate 394 refmences 395 index 397

object/relational persistence What is persistence? 5

object/relational persistence What is persistence? 5 contents foreword to the revised edition xix foreword to the first edition xxi preface to the revised edition xxiii preface to the first edition xxv acknowledgments xxviii about this book xxix about the