Spring Data JPA Tutorial - Java Based Configuration

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In the previous article, we have seen What is Spring Data JPA and its interfaces. In this article, we will discuss how we can configure the persistence layer of a Spring application that uses Spring Data JPA and Hibernate.
Note that we are not using Spring Boot. We are using the plain Spring framework to demonstrate configuring the persistence layer of a Spring application that uses Spring Data JPA and Hibernate.
For the Spring Boot project, check out Spring Boot with Spring Data JPA.

Configuring the Persistence Layer of a Spring Application

We can create the configuration class, which configures the persistence layer of a Spring application, by following these steps:
  1. Create the properties file that contains the properties used by our application context configuration class.
  2. Configure Datasource bean.
  3. Configure the entity manager factory bean.
  4. Configure the transaction manager bean.
  5. Enable annotation-driven transaction management.
  6. Configure Spring Data JPA.
  7. Read property file using @PropertySource Annotation
The below diagram shows easy steps to configure the persistence layer of a Spring application that uses Spring Data JPA and Hibernate:

But before we can get started, we have to create the configuration class that configures the persistence layer of our application. 

The source code of the PersistenceJPAConfig class looks as follows:
@Configuration
@ComponentScan({ "net.javaguides.springmvc" })
public class PersistenceJPAConfig {
}
  • @Configuration tags the class as a source of bean definitions for the application context.
  • @ComponentScan tells Spring to look for other components, configurations, and services in the hello package, allowing it to find the controllers.

1. Creating the Properties File - database.properties

# jdbc.X
jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/demo?useSSL=false
jdbc.user=root
jdbc.pass=root

# hibernate.X
hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
hibernate.show_sql=false
hibernate.hbm2ddl.auto=create-drop
hibernate.cache.use_second_level_cache=false
hibernate.cache.use_query_cache=false

2. Configuring the Datasource Bean

We can configure the Datasource bean by following these steps:
  • Ensure that the close() method of the created DataSource object is invoked when the application context is closed.
  • Configure the database connection. We need to set the name of the JDBC driver class, the JDBC URL, the username of a database user, and the password of the database user.
  • Create a new DriverManagerDataSource object and return the created object.
@Bean
public DataSource dataSource() {
    final DriverManagerDataSource dataSource = new DriverManagerDataSource();
    dataSource.setDriverClassName(env.getProperty("jdbc.driverClassName"));
    dataSource.setUrl(env.getProperty("jdbc.url"));
    dataSource.setUsername(env.getProperty("jdbc.user"));
    dataSource.setPassword(env.getProperty("jdbc.pass"));
    return dataSource;
}
Note that, in this sample code we are using DriverManagerDataSource datasource which is a simple implementation of the standard JDBC javax.sql.DataSource interface, configuring the plain old JDBC java.sql.DriverManager via bean properties, and returning a new java.sql.Connection from every getConnection call.

3. Configuring the Entity Manager Factory Bean

We can configure the entity manager factory bean by following these steps:
  1. Create a new LocalContainerEntityManagerFactoryBean object. We need to create this object because it creates the JPA EntityManagerFactory.
 final LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
  1. Configure the used datasource.
final LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
entityManagerFactoryBean.setDataSource(dataSource());
  1. Configure the Hibernate-specific implementation of the JpaVendorAdapter interface. It will initialize our configuration with the default settings that are compatible with Hibernate.
final LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
entityManagerFactoryBean.setDataSource(dataSource());
final HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
entityManagerFactoryBean.setJpaVendorAdapter(vendorAdapter);
  1. Configure the packages that are scanned for entity classes.
final LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
entityManagerFactoryBean.setDataSource(dataSource());
final HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
entityManagerFactoryBean.setJpaVendorAdapter(vendorAdapter);
entityManagerFactoryBean.setPackagesToScan(new String[] { "net.javaguides.springmvc.entity" });
  1. Configure the JPA properties that are used to provide additional configuration to the used JPA provider.
final Properties additionalProperties() {
 final Properties hibernateProperties = new Properties();
 hibernateProperties.setProperty("hibernate.hbm2ddl.auto", env.getProperty("hibernate.hbm2ddl.auto"));
 hibernateProperties.setProperty("hibernate.dialect", env.getProperty("hibernate.dialect"));
 hibernateProperties.setProperty("hibernate.cache.use_second_level_cache", env.getProperty("hibernate.cache.use_second_level_cache"));
 hibernateProperties.setProperty("hibernate.cache.use_query_cache", env.getProperty("hibernate.cache.use_query_cache"));
 // hibernateProperties.setProperty("hibernate.globally_quoted_identifiers", "true");
 return hibernateProperties;
}
The method that configures the entity manager factory bean looks as follows:
    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        final LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
        entityManagerFactoryBean.setDataSource(dataSource());
        entityManagerFactoryBean.setPackagesToScan(new String[] {
            "net.javaguides.springmvc.entity"
        });

        final HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        entityManagerFactoryBean.setJpaVendorAdapter(vendorAdapter);
        entityManagerFactoryBean.setJpaProperties(additionalProperties());

        return entityManagerFactoryBean;
    }

    final Properties additionalProperties() {
        final Properties hibernateProperties = new Properties();
        hibernateProperties.setProperty("hibernate.hbm2ddl.auto", env.getProperty("hibernate.hbm2ddl.auto"));
        hibernateProperties.setProperty("hibernate.dialect", env.getProperty("hibernate.dialect"));
        hibernateProperties.setProperty("hibernate.cache.use_second_level_cache", env.getProperty("hibernate.cache.use_second_level_cache"));
        hibernateProperties.setProperty("hibernate.cache.use_query_cache", env.getProperty("hibernate.cache.use_query_cache"));
        // hibernateProperties.setProperty("hibernate.globally_quoted_identifiers", "true");
        return hibernateProperties;
    }

    @Bean
    public DataSource dataSource() {
        final DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(env.getProperty("jdbc.driverClassName"));
        dataSource.setUrl(env.getProperty("jdbc.url"));
        dataSource.setUsername(env.getProperty("jdbc.user"));
        dataSource.setPassword(env.getProperty("jdbc.pass"));
        return dataSource;
    }

4. Configuring the Transaction Manager Bean

Because we are using JPA, we have to create a transaction manager bean that integrates the JPA provider with the Spring transaction mechanism. We can do this by using the JpaTransactionManager class as the transaction manager of our application.
We can configure the transaction manager bean by following these steps:
  1. Create a new JpaTransactionManager object.
 final JpaTransactionManager transactionManager = new JpaTransactionManager();
  1. Configure the entity manager factory whose transactions are managed by the created JpaTransactionManager object.
final JpaTransactionManager transactionManager = new JpaTransactionManager();
transactionManager.setEntityManagerFactory(emf);
The method that configures the transaction manager bean looks as follows:
    @Bean
    public PlatformTransactionManager transactionManager(final EntityManagerFactory emf) {
        final JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(emf);
        return transactionManager;
    }

5. Enabling Annotation-Driven Transaction Management

We can enable annotation-driven transaction management by annotating the PersistenceJPAConfig class with the @EnableTransactionManagement annotation. 
The relevant part of the PersistenceJPAConfig class looks as follows:
@Configuration
@EnableTransactionManagement
@ComponentScan({ "net.javaguides.springmvc" })
public class PersistenceJPAConfig {
}

6. Configuring Spring Data JPA

We can configure Spring Data JPA by following these steps:
Enable Spring Data JPA by annotating the PersistenceContext class with the @EnableJpaRepositories annotation and also configure the base packages that are scanned when Spring Data JPA creates implementations for our repository interfaces.
The relevant part of the PersistenceJPAConfig class looks as follows:
@Configuration
@EnableTransactionManagement
@ComponentScan({ "net.javaguides.springmvc" })
@EnableJpaRepositories(basePackages = "net.javaguides.springmvc.repository")
public class PersistenceJPAConfig {
}

7. Read property file using @PropertySource Annotation

We have created the database.properties file in step 1, which contains the properties used by our application context configuration class. Now we read these properties using @PropertySource annotation and configure them in respective beans.
@Configuration
@EnableTransactionManagement
@PropertySource({ "classpath:database.properties" })
@ComponentScan({ "net.javaguides.springmvc" })
@EnableJpaRepositories(basePackages = "net.javaguides.springmvc.repository")
public class PersistenceJPAConfig {

    @Autowired
    private Environment env;
}

Complete Configuration code - PersistenceJPAConfig class

After successfully configuring the persistence layer of our example application, our PersistenceJPAConfig class looks like this:
package net.javaguides.springmvc.config;

import java.util.Properties;

import javax.persistence.EntityManagerFactory;
import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
@EnableTransactionManagement
@PropertySource({
    "classpath:database.properties"
})
@ComponentScan({
    "net.javaguides.springmvc"
})
@EnableJpaRepositories(basePackages = "net.javaguides.springmvc.repository")
public class PersistenceJPAConfig {

    @Autowired
    private Environment env;

    public PersistenceJPAConfig() {
        super();
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        final LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
        entityManagerFactoryBean.setDataSource(dataSource());
        entityManagerFactoryBean.setPackagesToScan(new String[] {
            "net.javaguides.springmvc.entity"
        });

        final HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        entityManagerFactoryBean.setJpaVendorAdapter(vendorAdapter);
        entityManagerFactoryBean.setJpaProperties(additionalProperties());

        return entityManagerFactoryBean;
    }

    final Properties additionalProperties() {
        final Properties hibernateProperties = new Properties();
        hibernateProperties.setProperty("hibernate.hbm2ddl.auto", env.getProperty("hibernate.hbm2ddl.auto"));
        hibernateProperties.setProperty("hibernate.dialect", env.getProperty("hibernate.dialect"));
        hibernateProperties.setProperty("hibernate.cache.use_second_level_cache", env.getProperty("hibernate.cache.use_second_level_cache"));
        hibernateProperties.setProperty("hibernate.cache.use_query_cache", env.getProperty("hibernate.cache.use_query_cache"));
        // hibernateProperties.setProperty("hibernate.globally_quoted_identifiers", "true");
        return hibernateProperties;
    }

    @Bean
    public DataSource dataSource() {
        final DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(env.getProperty("jdbc.driverClassName"));
        dataSource.setUrl(env.getProperty("jdbc.url"));
        dataSource.setUsername(env.getProperty("jdbc.user"));
        dataSource.setPassword(env.getProperty("jdbc.pass"));
        return dataSource;
    }

    @Bean
    public PlatformTransactionManager transactionManager(final EntityManagerFactory emf) {
        final JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(emf);
        return transactionManager;
    }

    @Bean
    public PersistenceExceptionTranslationPostProcessor exceptionTranslation() {
        return new PersistenceExceptionTranslationPostProcessor();
    }
}

The Spring Data JPA XML Configuration

<?xml version="1.0" encoding="UTF-8"?>
<beans
    xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:tx="http://www.springframework.org/schema/tx"
   xsi:schemaLocation="
      http://www.springframework.org/schema/beans 
      http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
      http://www.springframework.org/schema/tx 
      http://www.springframework.org/schema/tx/spring-tx-3.2.xsd">
    <bean id="myEmf"
     class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="packagesToScan" value="org.baeldung.persistence.model" />
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
        </property>
        <property name="jpaProperties">
            <props>
                <prop key="hibernate.hbm2ddl.auto">create-drop</prop>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
            </props>
        </property>
    </bean>
    <bean id="dataSource"
     class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost:3306/spring_jpa" />
        <property name="username" value="tutorialuser" />
        <property name="password" value="tutorialmy5ql" />
    </bean>
    <bean id="transactionManager"
     class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="myEmf" />
    </bean>
    <tx:annotation-driven />
    <bean id="persistenceExceptionTranslationPostProcessor" class=
     "org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />
</beans>

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