Enabling HicariCP manually in Spring Boot

I have manually set up Spring Boot with multiple databases. Only problem is that I do not use properties file, but a YAML file, and I manually setup the dual DB connectivity.

@AllArgsConstructor
public abstract class PersistenceConfiguration {

    private final String driverClassName;
    private final String url;
    private final String username;
    private final String password;
    private final String[] packagesToScan;
    private final String hbm2ddl;
    private final String dialect;

    public DataSource dataSource() {

        final DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(driverClassName);
        dataSource.setUrl(url);
        dataSource.setUsername(username);
        dataSource.setPassword(password);

        return dataSource;
    }

    public LocalContainerEntityManagerFactoryBean entityManager() {

        final LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(dataSource());
        em.setPackagesToScan(packagesToScan);

        final HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        em.setJpaVendorAdapter(vendorAdapter);

        final HashMap<String, Object> properties = new HashMap<>();
        properties.put("hibernate.hbm2ddl.auto", hbm2ddl);
        properties.put("hibernate.dialect", dialect);
        em.setJpaPropertyMap(properties);

        return em;
    }

    public PlatformTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
        return new JpaTransactionManager(entityManagerFactory);
    }
}


@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = "adjustmentEntityManagerFactory",
        transactionManagerRef = "adjustmentTransactionManager",
        basePackages = {"com.gtn.ca_adjustments.repository.adjustment"}
)
public class AdjustmentPersistenceConfiguration extends PersistenceConfiguration {

    @Autowired
    public AdjustmentPersistenceConfiguration(Environment env) {
        super(
                env.getProperty("spring.datasource.driverClassName"),
                env.getProperty("spring.datasource.url"),
                env.getProperty("spring.datasource.username"),
                env.getProperty("spring.datasource.password"),
                new String[]{"com.gtn.ca_adjustments.entity.adjustment"},
                "none",
                env.getProperty("hibernate.dialect")
        );
    }

    @Bean(name = "adjustmentDataSource")
    @Primary
    @Override
    public DataSource dataSource() {
        return super.dataSource();
    }

    @Primary
    @Bean(name = "adjustmentEntityManagerFactory")
    @Override
    public LocalContainerEntityManagerFactoryBean entityManager() {
        return super.entityManager();
    }

    @Bean(name = "adjustmentTransactionManager")
    @Primary
    @Override
    public PlatformTransactionManager transactionManager(
            @Qualifier("adjustmentEntityManagerFactory") EntityManagerFactory entityManagerFactory
    ) {
        return super.transactionManager(entityManagerFactory);
    }
}

I have seen examples to configure HicariCP via properties file:

first.datasource.jdbc-url=jdbc:oracle:thin:@*a host*
first.datasource.username=user1
first.datasource.password=xxxxxxxxx
first.datasource.poolName=FirstPool
first.datasource.maximumPoolSize=100
first.datasource.maxLifetime=10000

How can I enable HicariCP manually via java code. I do not see methods to configure HicariCP like other properties such as username, password etc. (I use spring boot 2.7 with java 17)

Based on your question it looks like you need to configure 2 datasources manually via java code then this is what I am suggesting-- Using Qualifier for identification purpose & returning 2 different beans based on different database properties --

public class DataSource {
          
    @Bean
    @Qualifier("firstDataSource")
    public DataSource firstDataSource(){
        HikariConfig config = new HikariConfig();
        config.setJdbcUrl( "jdbc_url" );
        config.setUsername( "database_username" );
        config.setPassword( "database_password" );
        ....
        return new HikariDataSource( config );
    }

    @Bean
    @Qualifier("secondDataSource")
    public DataSource secondDataSource(){
        HikariConfig config = new HikariConfig();
        config.setJdbcUrl( "jdbc_url" );
        config.setUsername( "database_username" );
        config.setPassword( "database_password" );
        ....
        return new HikariDataSource( config );
    }
}

You can put these bean definitions in your configuration class as well.