In this document,we list two main part.
By default, Spring Data uses Hibernate as the default JPA implementation provider.However, Hibernate is certainly not the only JPA implementation available to us.In this document, we’ll go through steps necessary to set up EclipseLink as the implementation provider for Spring Data JPA.The migration will not need to convert any Hibernate annotations to EclipseLink annotations in application code.
Since we want to use EclipseLink instead as the JPA provider, we don't need it anymore.Therefore we can remove it from our project by excluding its dependencies:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
<exclusions>
<exclusion>
<groupId>org.hibernate</groupId>
<artifactId>*</artifactId>
</exclusion>
</exclusions>
</dependency>
To use it in our Spring Boot application, we just need to add the org.eclipse.persistence.jpa dependency in the pom.xml of our project.
<properties>
<eclipselink.version>2.6.0</eclipselink.version>
</properties>
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>org.eclipse.persistence.jpa</artifactId>
<version>${eclipselink.version}</version>
</dependency>
EclipseLink requires the domain types to be instrumented to implement lazy-loading. This can be achieved either through static weaving at compile time or dynamically at class loading time (load-time weaving). In Apache Griffin,we use static weaving in pom.xml.
<build>
<plugins>
<plugin>
<groupId>com.ethlo.persistence.tools</groupId>
<artifactId>eclipselink-maven-plugin</artifactId>
<version>2.7.0</version>
<executions>
<execution>
<phase>process-classes</phase>
<goals>
<goal>weave</goal>
</goals>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>org.eclipse.persistence.jpa</artifactId>
<version>${eclipselink.version}</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
JpaBaseConfiguration is an abstract class which defines beans for JPA in Spring Boot. Spring provides a configuration implementation for Hibernate out of the box called HibernateJpaAutoConfiguration. However, for EclipseLink, we have to create a custom configuration.To customize it, we have to implement some methods like createJpaVendorAdapter() or getVendorProperties(). First, we need to implement the createJpaVendorAdapter() method which specifies the JPA implementation to use. Also, we have to define some vendor-specific properties which will be used by EclipseLink.We can add these via the getVendorProperties() method. Add following code as a class to org.apache.griffin.core.config package in Apache Griffin project.
@Configuration
@ComponentScan("org.apache.griffin.core")
public class EclipseLinkJpaConfig extends JpaBaseConfiguration {
protected EclipseLinkJpaConfig(DataSource ds, JpaProperties properties,
ObjectProvider<JtaTransactionManager> jtm,
ObjectProvider<TransactionManagerCustomizers> tmc) {
super(ds, properties, jtm, tmc);
}
@Override
protected AbstractJpaVendorAdapter createJpaVendorAdapter() {
return new EclipseLinkJpaVendorAdapter();
}
@Override
protected Map<String, Object> getVendorProperties() {
Map<String, Object> map = new HashMap<>();
map.put(PersistenceUnitProperties.WEAVING, "false");
map.put(PersistenceUnitProperties.DDL_GENERATION, "create-or-extend-tables");
return map;
}
}
You need to configure properties according to the database you use in Apache Griffin. Please see Mysql and postgresql switch to configure.
Here we'll go through steps necessary to migrate applications from using EclipseLink JPA to using Hibernate JPA.The migration will not need to convert any EclipseLink annotations to Hibernate annotations in application code.
In Apache Griffin, we provide hibernate_mysql_pom.xml file for hibernate and mysql. If you want to quick use hibernate and mysql with jar, firstly you should configure properties and then use command mvn clean package -f pom_hibernate.xml to package jar.
By default, Spring Data uses Hibernate as the default JPA implementation provider.So we just add spring-boot-starter-data-jpa dependency.If you have already added it, skip this step.
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
If you don't want to remove EclipseLink,you can skip this step.
remove EclipseLink dependency
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>org.eclipse.persistence.jpa</artifactId>
<version>${eclipselink.version}</version>
</dependency>
remove EclipseLink static weaving
<plugin>
<groupId>com.ethlo.persistence.tools</groupId>
<artifactId>eclipselink-maven-plugin</artifactId>
<version>2.7.0</version>
<executions>
<execution>
<phase>process-classes</phase>
<goals>
<goal>weave</goal>
</goals>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>org.eclipse.persistence.jpa</artifactId>
<version>${eclipselink.version}</version>
</dependency>
</dependencies>
</plugin>
remove EclipseLinkJpaConfig class
remove EclipseLinkJpaConfig class in org.apache.griffin.core.config package.
You need to configure properties according to the database you use in Apache Griffin. Please see Mysql and postgresql switch to configure.