How to retrieve the datasource used by a persistence unit programmatically

Question

...without actually reading and parsing the persistence.xml

I can retrieve the name of the persistence unit of an EntityManager using the p

Answer 1

DataSource dataSource = (DataSource) 
em.getEntityManagerFactory().getProperties()
            .get(org.hibernate.cfg.AvailableSettings.JPA_JTA_DATASOURCE);

You can retrieve datasoure with hibernate. Tested with Hibernate 5.3

Answer 2

In a Spring environment you can use this:

import org.springframework.orm.jpa.EntityManagerFactoryInfo;
...

@PersistenceContext
EntityManager entityManager;

public DataSource getDataSourceFromHibernateEntityManager() {
   EntityManagerFactoryInfo info = (EntityManagerFactoryInfo) entityManager.getEntityManagerFactory();
   return info.getDataSource();
}

Answer 3

in SpringBoot environment you can use the following:

@PersistenceContext
EntityManager entityManager;

private HikariDataSource getDataSourceFromHibernateEntityManager() {
    EntityManagerFactoryInfo info = (EntityManagerFactoryInfo) entityManager.getEntityManagerFactory();
    return (HikariDataSource) info.getDataSource();
}

public String getDataSourceProperties() {
    HikariDataSource dataSource = getDataSourceFromHibernateEntityManager();
    return "DataSource properties:" +
            "URL: " + dataSource.getJdbcUrl() + "\n" +
            "Default Schema: " + dataSource.getPoolName() + "\n" +
            "Driver Class Name: " + dataSource.getDriverClassName() + "\n" +
            "Username: " + dataSource.getUsername() + "\n";
}

Answer 4

Here's what helped me. I use HikariCP but I don't think it matters.

Basically what needs to be done is

1. find a service registry
2. get service by org.hibernate.engine.jdbc.connections.spi.ConnectionProvider class
3. unwrap it to javax.sql.DataSource.

Service registry can be retrieved from EntityManager

((SessionImpl) em).getFactory().getServiceRegistry()

or from EntityManagerFactory directly

((SessionFactoryImpl) entityManagerFactory).getServiceRegistry()