Multiple entityManagerFactory without persistence.xml

Question

I've been working in a project that has been using spring mvc 4 and JPA configuration beans are created in java class without persistence.xml just like the code below.

package test.conf;

import java.util.Properties;
import javax.persistence.EntityManagerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
@EnableTransactionManagement
public class JPAConfiguration {

    @Bean
    @Primary
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        LocalContainerEntityManagerFactoryBean factoryBean = new LocalContainerEntityManagerFactoryBean();
        JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();

        factoryBean.setJpaVendorAdapter(vendorAdapter);
        factoryBean.setDataSource(dataSource());    

        Properties props = new Properties();
        props.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQL5Dialect");
        props.setProperty("hibernate.show_sql", "false");
        props.setProperty("hibernate.hbm2ddl.auto", "update");

        factoryBean.setJpaProperties(props);
        String [] packages = {"test.model"};
        factoryBean.setPackagesToScan(packages);

        return factoryBean;
    }

    @Bean
    @Primary
    public DriverManagerDataSource dataSource() {

        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setUsername("root");
        dataSource.setPassword("root");
        dataSource.setUrl("jdbc:mysql://localhost:3306/database");
        dataSource.setDriverClassName("com.mysql.jdbc.Driver");
        return dataSource;
    }

    @Bean
    @Primary
    public JpaTransactionManager transactionManager(EntityManagerFactory emf){
        return new JpaTransactionManager(emf);
    }

}

This is working fine, but now, we will have to connect to a second database (ORACLE) and there will be necessary a second entity manager factory. How can I do this ? I have found examples creating a second persistence unit on persistence.xml but I don't have the persistence.xml in that project. Others teach how to create connection to multiple datasources using spring boot, but this isn't a spring boot project.

I tried to create a second JPAConfiguration class for the other database and then specifying a factoryBean.setPersistenceUnitName(""); for each entitymanagerfactorybean, but seems that Spring is messing up since it always initializes one the persiscence unit twice.

Answer 1

You need have second datasource details in properties

#second db ...
spring.secondDatasource.url = [url]
spring.secondDatasource.username = [username]
spring.secondDatasource.password = [password]
spring.secondDatasource.driverClassName = oracle.jdbc.OracleDriver

Then create your configuration class that will have all configuration to use this second datasource and enable jpa repositry with this second datasource.

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(entityManagerFactoryRef = "secondEntityManagerFactory",
        transactionManagerRef = "secondTransactionManager",
        basePackages = {"com.server.second.repo"}
)
public class SecondDBConfiguration  

@Bean("secondDatasource")
@ConfigurationProperties(prefix="spring.secondDatasource")
public DataSource secondaryDataSource() {
return DataSourceBuilder.create().build();
}

@Bean(name = "secondEntityManagerFactory")
public LocalContainerEntityManagerFactoryBean
secondEntityManagerFactory(
        EntityManagerFactoryBuilder builder,
        @Qualifier("secondDatasource") DataSource dataSource
) {
    return
            builder
                    .dataSource(dataSource)
                    .packages("com.server.shadow.domain")
                    .persistenceUnit("shadow")
                    .build();
}
@Bean(name = "secondTransactionManager")
public PlatformTransactionManager secondTransactionManager(
        @Qualifier("secondEntityManagerFactory") EntityManagerFactory
                secondEntityManagerFactory
) {
    return new JpaTransactionManager(secondEntityManagerFactory);
}