Overview
At some point of time, as your project scope grows, the Hibernate mapping XML files are going to get to a point where it becomes very difficult to maintain. This is where the annotation-based configuration comes in. It took me a few years to convince myself that annotation-based configuration is the way to go. Change is hard, yet necessary.
This tutorial covers the following:-
- Upgrade Hibernate from 3.x to 4.x.
- Configure Spring-Hibernate integration to replace XML-based configuration with annotation-based configuration.
- Configure Joda-Time to work properly in Hibernate 4.
- Activate @Transactional instead of relying on AOP-based transaction.
Maven Dependencies
Change the Hibernate dependency version from 3.x to 4.x. On top of that, add org.jadira.usertype:usertype.core:[version] dependency to get Joda-Time to work properly with Hibernate 4.
Hibernate 3.x
<dependency>
<groupid>org.hibernate</groupid>
<artifactid>hibernate-core</artifactid>
<version>3.6.9.Final</version>
</dependency>
<dependency>
<groupid>joda-time</groupid>
<artifactid>joda-time</artifactid>
<version>2.3</version>
</dependency>
<dependency>
<groupid>joda-time</groupid>
<artifactid>joda-time-hibernate</artifactid>
<version>1.3</version>
</dependency>
Hibernate 4.x
<dependency>
<groupid>org.hibernate</groupid>
<artifactid>hibernate-core</artifactid>
<version>4.2.6.Final</version>
</dependency>
<dependency>
<groupid>joda-time</groupid>
<artifactid>joda-time</artifactid>
<version>2.3</version>
</dependency>
<dependency>
<groupid>joda-time</groupid>
<artifactid>joda-time-hibernate</artifactid>
<version>1.3</version>
</dependency>
<dependency>
<groupid>org.jadira.usertype</groupid>
<artifactid>usertype.core</artifactid>
<version>3.1.0.CR8</version>
</dependency>
By the way, if you don’t know what Joda-Time is or haven’t use it by now, then you should be spanked by the Date God. With that added dependency, the @Type for date field will look a little different ( see here for more info ):-
@Entity
@Table(name = "MrMeow")
public class MrMeow implements Ideable, Serializable {
...
@Column
@Type(type = "org.jadira.usertype.dateandtime.joda.PersistentLocalDate")
private LocalDate whenMeowed;
}
Spring Integration
Hibernate 3.x
This configuration uses Hibernate XML mapping files to configure mappings between the domain objects and the database tables. Further, AOP is used to configure the transaction.
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="dataSource" ref="dataSource">
<property name="configLocation" value="classpath:hibernate.cfg.xml">
</property></property>
</bean>
<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory">
</property></bean>
<tx:advice id="txAdvice">
<tx:attributes>
<tx:method name="*" propagation="REQUIRED">
</tx:method></tx:attributes>
</tx:advice>
<aop:config proxy-target-class="true">
<aop:advisor pointcut="execution(* myproject..*.*(..))" advice-ref="txAdvice">
</aop:advisor></aop:config>
Hibernate 4.x
This configuration scans myproject.domain package, which contains all Hibernate annotated domain classes. Further, it activates @Transactional so that you can place it in your code to manage the transaction.
<tx:annotation-driven transaction-manager="transactionManager"/>
<bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory"/>
</bean>
<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<property name="hibernateProperties">
<props>
<!-- Configure your Hibernate dialect -->
<prop key="hibernate.dialect">org.hibernate.dialect.SQLServerDialect</prop>
<prop key="hibernate.show_sql">false</prop>
</props>
</property>
<property name="packagesToScan">
<list>
<!-- Configure your domain package -->
<value>myproject.domain</value>
</list>
</property>
</bean>
web.xml
Change filter class for OpenSessionInViewFilter.
Hibernate 3.x
<filter>
<filter-name>hibernateFilter</filter-name>
<filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>hibernateFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
Hibernate 4.x
<filter>
<filter-name>hibernateFilter</filter-name>
<filter-class>org.springframework.orm.hibernate4.support.OpenSessionInViewFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>hibernateFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
Domain Classes
Finally, time to annotate your Hibernate domain classes!
Helpful Note
Please make sure you don’t have JPA 1.x in your classpath in the first place. Read java.lang.NoSuchMethodError: javax/persistence/OneToMany.orphanRemoval()Z for more information.