This is a presentation on Spring 3 annotations on a web stack. It includes basic spring annotation details, working with jpa, and the new MVC stuff. The code samples add a lot. I'll try to get them up on github.com.
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Spring 3 Annotated Development
1. Spring - ADD Developer
Annotated Driven Development
Friday, February 13, 2009
2. About Speaker
Speaker @ JavaOne, NFJS, Devcon, Borcon
Sun Certified Java 2 Architect.
Instructor for VisiBroker for Java, OOAD, Rational Rose,
and Java Development.
JBoss Certified Developer
Friday, February 13, 2009
3. Agenda
Annotations and the MV
Spring 2.5/3 Annotations
– Spring Business Tier
Spring Data Tier
Spring MVC Tier
Summary
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4. Industry Forces
Annotations
– EJB 3.X
– JSR-250 Common Annotations
– JSR-299 Web Beans
Guice / SEAM
XML... way too much XML
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22. Spring 2.x Data Access Annotations
@Transactional
– Provides annotation driven demarcation for
transactions
@Repository
– Indicates that a class functions as a repository or
a data access object (DAO)
– Exceptions are transparently translated
• Springs DataAccessException Hierarchy
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23. Spring 2.5 Stereotypes
@Component **
– Indicates that a class is a component
– Class is a candidate for auto-detection
– Custom component extensions
@Controller
– Specialized Component
– Typically used with RequestMapping annotation
– Discussed in section on web mvc
@Repository
– 2.0 stereotype… previously mentioned
– Now an extension of @Component
@Service
– Intended to be a business service facade
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24. Spring 2.5 Factory Annotations
@Autowired
– Marks a constructor, field, setter or config method for injection.
– Fields are injected
• After construction
• Before config methods
– @Autowired(required=false)
– Config:
AutowiredAnnotationBeanPostProcessor
•
@Configurable
– Marks class as being eligible for Spring-driven configuration
– Used with AspectJ
@Qualifier
– Qualifies a bean for autowiring
– May be customized
@Required
– Marks a method as being injection required
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25. Types of Injections
Constructor
Setter
Field
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26. New Injection Type
configuration
method
with any
number of
arguments
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27. Let me Qualify that
@Autowired
@Qualifier(“xyzDataSourceName”)
Private DataSource dataSource
Or
@Autowired
public void init(@Qualifier(“xyzNAme”) DataSource
dataSource, Object2 obj)
{…}
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30. JPA - Specification
Packaging
Entities
Entity Operations
Queries
Metadata
Life-cycle Model
Callbacks
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31. Persistence.xml
In the classpath under the META-INF directory.
<persistence-unit name=quot;unit1quot; transaction-type=quot;RESOURCE_LOCALquot;>
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<properties>
<property name=quot;hibernate.hbm2ddl.autoquot; value=quot;createquot;/>
<property name=quot;hibernate.ejb.autodetectionquot; value=quot;classquot;/>
<property name=quot;hibernate.connection.urlquot;
value=quot;jdbc:hsqldb:hsql://localhost:1234/employeequot;/>
<property name=quot;hibernate.connection.driver_classquot;
value=quot;org.hsqldb.jdbcDriverquot;/>
<property name=quot;hibernate.connection.usernamequot; value=quot;saquot;/>
<property name=quot;hibernate.connection.passwordquot; value=quot;quot;/>
</properties>
</persistence-unit>
</persistence>
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32. Customer Entity (from spec)
@Entity(access=FIELD)
public class Customer {
@Id(generate=AUTO) Long id;
@Version protected int version;
@ManyToOne Address address;
@Basic String description;
@OneToMany(targetEntity=com.acme.Order.class,
mappedBy=quot;customerquot;)
Collection orders = new Vector();
@ManyToMany(mappedBy=quot;customersquot;)
Set<DeliveryService> serviceOptions = new HashSet();
public Customer() {}
public Collection getOrders() { return orders; }
public Set<DeliveryService> getServiceOptions() {
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33. JPA Persistence Interfaces
EntityManager
– Interface to interact with persistence context.
– @PersistenceContext
EntityManagerFactory
– Creates an EntityManager
– @PersistenceUnit
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34. Acquiring a Manager
Injection in Stateless Bean
@PersistenceContext
public EntityManager em;
OR
@PersistenceContext(unitName=quot;orderquot;)
EntityManager em;
From Java Application
EntityManagerFactory emf =
Persistence.createEntityManagerFactory(quot;unit1quot;);
EntityManager em = emf.createEntityManager();
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35. Spring 2 JPA Support
org.springframework.orm.jpa package
Contains subset of the JPA container
JpaDaoSupport
– similar to other DAO support classes like
HibernateDaoSupport
LocalEntityManagerFactoryBean
– Provides resource bootstrapping for non-jndi lookups
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36. Spring / JPA Approaches
JpaDaoSupport Approach
– Not preferred approach
– Similar to HibernateDaoSupport
– Requires Spring Configuration of the
EntityManager
Pure JPA Approach
– Preferred approach
– No spring references necessary in the code
• with the exception of @Transactional
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37. Approach 2: Spring / Pure JPA Configuration
Leverage the persistence.xml in classpath:/META-INF
<bean id=quot;entityManagerFactoryquot;
class=quot;org.springframework.orm.jpa.LocalEntityManagerFactoryBeanquot; >
<property name=quot;persistenceUnitNamequot; value=quot;unit1quot;/>
</bean>
DAO with no Spring references, however it contains
@PersistenceContext annotated EntityManager
<bean id=quot;conferenceDaoquot;
class=quot;com.codementor.jpa.domain.ConferenceDAOImplquot;/>
Spring configuration which injects JPA annotationed
EntityManager
<bean
class=quot;org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProces
sor“ />
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38. Pure JPA Code Example: ConferenceDaoImpl
package com.nfjs.jpa;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import org.springframework.transaction.annotation.Transactional;
public class ConferenceDAOImpl implements ConferenceDAO {
@PersistenceContext
private EntityManager entityManager;
public void setEntityManager(EntityManager entityManager) {
this.entityManager = entityManager;
}
– ...
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39. Pure JPA Spring Configuration
<bean id=quot;entityManagerFactoryquot;
class=quot;org.springframework.orm.jpa.LocalEntityManagerFactoryBeanquot; >
<property name=quot;persistenceUnitNamequot; value=quot;nfjsquot;/>
</bean>
<bean id=quot;conferenceDaoquot; class=quot;com.nfjs.jpa.ConferenceDAOImplquot;/>
<bean
class=quot;org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessorquot;
/>
</beans>
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40. No PU No Problem
The LocalContainerEntityManagerFactoryBean can be
configured with all Persistent Unit information.
<bean id=quot;entityManagerFactoryquot;
class=quot;org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBeanquot;>
<property name=quot;dataSourcequot; ref=quot;dataSourcequot;/>
<property name=quot;jpaVendorAdapterquot;>
<bean class=quot;org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapterquot;>
<property name=quot;showSqlquot; value=quot;truequot;/>
<property name=quot;generateDdlquot; value=quot;truequot;/>
<property name=quot;databasePlatformquot;
value=quot;org.hibernate.dialect.HSQLDialectquot;/>
</bean>
</property>
</bean>
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41. Transactions
XML Configuration
<tx:annotation-driven />
Annotation
@Transactional(readOnly = false,
propagation = Propagation.REQUIRES_NEW)
Public void doSomething() {
** transaction manger bean id must be transactionManger or configured
with the xml configuration above.
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42. Test JPA with Spring
public class SpeakerDAOTest extends AbstractJpaTests {
private SpeakerDAO speakerDao;
public void setSpeakerDao(SpeakerDAO speakerDao) {
this.speakerDao = speakerDao;
}
protected String[] getConfigLocations() {
return new String[] {quot;classpath:/jpaContext.xmlquot;};
}
protected void onSetUpInTransaction() throws Exception {
jdbcTemplate.execute(
quot;insert into speaker (id, name, company) values (1, 'Ken', 'CodeMentor')quot;);
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43. AbstractJpaTests Benefits
getConfigLocations ()
– Separates test from production configuration
– Allows for multiple configurations
Injected Dependencies By Type
– field references
Every Test
– Starts a Transactions
– Rolls back Transaction
Leverage jdbcTemplate for SQL checks
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46. Spring 2.5 MVC Annotations
@Controller
– Stereotype used to “Controller” of MVC
– Scanned for RequestMappings
@RequestMapping
– Annotates a handler method for a request
– Very flexible
@RequestParam
– Annotates that a method parameter should be bound to a
web request parameter
@SessionAttributes
– Marks session attributes that a handler uses
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47. New Controller Issues
Doesn’t implement an Interface
Multiple request mappings
High degree of flexibility
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51. A World Without Rules
Return Type?
Parameters?
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52. @RequestMapping - Extreme Flexibility
Parameters can be
– Request / response / session
– WebRequest
– InputStream
– OutputStream
– @RequestParam
– +++
Return types
– ModelAndView Object
– Model Object
– Map for exposing model
– View Object
– String which is a view name
– Void… if method wrote the response content directly
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53. Spring 2.5 Controller Example
@Controller
public class ConfController {
@Autowired
private confDB confDB;
@RequestMapping(quot;/sessionListquot;)
public String showSessionList(ModelMap model) {
model.addAttribute(quot;sessionsquot;, this.confDB.getSessions());
return quot;sessionListquot;;
}
@RequestMapping(quot;/speakerImagequot;)
public void streamSpeakerImage(@RequestParam(quot;namequot;) String name,
OutputStream outputStream) throws IOException {
this.confDB.getSpeakerImage(name,outputStream);
}
@RequestMapping(quot;/clearDatabasequot;)
public String clearDB() {
this.confDB.clear();
return quot;redirect:sessionListquot;;
}
}
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54. Spring MVC By Convention
Conventions:
hotel = HotelController
GET /hotel/list list = method
View selected
from request
path
Added to
Model
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