Use native JPA API
Since Spring 3.0, Spring embrace JPA quickly, and JPA is the first class citizen in Spring core framework. And in the latest Spring, JPA support is improved and the usage of JPA is more friendly than Hibernate.Configuration
An example of XML format configuration is shown below:<jdbc:embedded-database id="dataSource" >
</jdbc:embedded-database>
<bean class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
id="entityManagerFactory">
<property name="persistenceUnitName" value="persistenceUnit" />
<property name="dataSource" ref="dataSource" />
<property name="persistenceProviderClass" value="org.hibernate.ejb.HibernatePersistence"></property>
<property name="packagesToScan">
<array>
<value>com.hantsylabs.example.spring.model</value>
</array>
</property>
<property name="jpaProperties">
<value>
hibernate.format_sql=true
hibernate.show_sql=true
hibernate.hbm2ddl.auto=create
</value>
</property>
</bean>
<bean class="org.springframework.orm.jpa.JpaTransactionManager"
id="transactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<context:component-scan
base-package="com.hantsylabs.example.spring.dao,com.hantsylabs.example.spring.jpa">
</context:component-scan>
Firstly, it declares a DataSource bean.Then registers a EntityManagerFactoryBean bean, there are two version of EntityManagerFactoryBean are provided in Spring.
- LocalEntityManagerFactoryBean reads the standard JPA configuration file from /META-INF/peresistence.xml in the project and prepare a JPA EntityManagerFactory at runtime.
- LocalContainerEntityManagerFactoryBean is an advanced version and it provides more features. It is more friendly for container environment. It allow you specify the location of persistence.xml file. You can also configure a Spring loadTimeWeaver. Use this version, you can reuse the DataSource bean, and override the properties. In another word, you are free from maintaining the JPA specific configuration file( /META-INF/persistence.xml), you do not need it at all.
At last declare a JPA transaction manager.
The following is the Java configuration example, it is equivalent to the before XML format.
@Configuration
@ComponentScan(basePackages = { "com.hantsylabs.example.spring.dao",
"com.hantsylabs.example.spring.jpa" })
public class JpaConfig {
@Bean
public DataSource dataSource() {
return new EmbeddedDatabaseBuilder().build();
}
@Bean
public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
LocalContainerEntityManagerFactoryBean emf = new LocalContainerEntityManagerFactoryBean();
emf.setDataSource(dataSource());
emf.setPackagesToScan("com.hantsylabs.example.spring.model");
emf.setPersistenceProvider(new HibernatePersistence());
emf.setJpaProperties(jpaProperties());
return emf;
}
private Properties jpaProperties() {
Properties extraProperties = new Properties();
extraProperties.put("hibernate.format_sql", "true");
extraProperties.put("hibernate.show_sql", "true");
extraProperties.put("hibernate.hbm2ddl.auto", "create");
return extraProperties;
}
@Bean
public PlatformTransactionManager transactionManager() {
return new JpaTransactionManager(entityManagerFactory().getObject());
}
}
Example codes
@Repository
public class JpaConferenceDaoImpl implements ConferenceDao {
private static final Logger log = LoggerFactory
.getLogger(JpaConferenceDaoImpl.class);
@PersistenceContext
private EntityManager entityManager;
@Override
public Conference findById(Long id) {
return (Conference) entityManager.find(Conference.class, id);
}
}
As you see, it uses @PersistenceContext to inject the JPA EntityManager bean, there is only one Spring specific @Repository annotation in the above codes.If you are using JSR330, you can replace the @Repository with @Named, we will discuss this topic in further posts.
@Named
public class JpaConferenceDaoImpl implements ConferenceDao {
@PersistenceContext
private EntityManager entityManager;
}
Now, the above codes are no difference between Spring and Java EE, it
can be run in Spring(especially a Servlet container, such as Apache
Tomcat, Jetty) and any standard Java EE 6 container(for example JBoss AS
7, Glassfish 3.1). Of course you have to contribute extra effort on the
base configuration for different platform.Check out the codes from my github.com, https://github.com/hantsy/spring-sandbox.
评论