SAAS| AbstractRoutingDataSource

@Configuration
public class MultiTenantManager {

    private final ThreadLocal<String> currentTenant = new ThreadLocal<>();
    private final Map<Object, Object> tenantDataSources = new ConcurrentHashMap<>();
    private final DataSourceProperties properties;

    private AbstractRoutingDataSource multiTenantDataSource;

    public MultiTenantManager(DataSourceProperties properties) {
        this.properties = properties;
    }

    @Bean
    public DataSource dataSource() {
        multiTenantDataSource = new AbstractRoutingDataSource() {
            @Override
            protected Object determineCurrentLookupKey() {
                return currentTenant.get();
            }
        };
        multiTenantDataSource.setTargetDataSources(tenantDataSources);
        multiTenantDataSource.setDefaultTargetDataSource(defaultDataSource());
        multiTenantDataSource.afterPropertiesSet();
        return multiTenantDataSource;
    }

    public void addTenant(String tenantId, String url, String username, String password) throws SQLException {

        DataSource dataSource = DataSourceBuilder.create()
                .driverClassName(properties.getDriverClassName())
                .url(url)
                .username(username)
                .password(password)
                .build();

        // Check that new connection is 'live'. If not - throw exception
        try(Connection c = dataSource.getConnection()) {
            tenantDataSources.put(tenantId, dataSource);
            multiTenantDataSource.afterPropertiesSet();
        }
    }

    public void setCurrentTenant(String tenantId) {
        currentTenant.set(tenantId);
    }

    private DriverManagerDataSource defaultDataSource() {
        DriverManagerDataSource defaultDataSource = new DriverManagerDataSource();
        defaultDataSource.setDriverClassName("org.h2.Driver");
        defaultDataSource.setUrl("jdbc:h2:mem:default");
        defaultDataSource.setUsername("default");
        defaultDataSource.setPassword("default");
        return defaultDataSource;
    }
}