Develop Reference

How to properly close a JdbcTemplate DataSource connection?

I want to create a one-shot database connection, based on spring classes.
To prevent spring loading the datasource on startup, I create it explicit when needed (only occasionally). I don't need any connection pooling, transactions and stuff like that.
DriverManagerDataSource ds = new DriverManagerDataSource(props.getUrl(), props.getUsername(), props.getPassword());
JdbcTemplate jdbc = new JdbcTemplate(ds);
jdbc.execute(...);
Question: how can I afterwards close/destroy the datasource and any open connections explicit?

Set maxConnectionLimit to Manually created connection using Spring DataSourceBuilder.create()

Using application.properties we can provide the
spring.datasource.hikari.maximum-pool-size=10
as spring using the Hikari connection pooling by default.
But when we are creating datasource manually as a specific requirement we cannot use the application.properties.
Scenario.
User will configure the datasource dynamically and that connection object should be available from thereafter.
For this we are creating DatasourceBuilder.create().build() method to create a datasource connection object and set it into the bean factory.
But while creating a datasource connection object using DataSourceBuilder.create().build() method it is creating connection pooling and 10 connection to the database at the same time.
We wanted to avoid that connection pooing and have only one connection.
How do I do that?

While creating the custom datasource we can create an instance of HikariDataSource instead of DataSource.
Assuming you are using Spring default Connection pooling (Hikari)
public DataSource createCustomConnection(String driverClass, String url, String username, String password) {
HikariConfig config = new HikariConfig();
config.setDriverClassName(driverClass);
config.setJdbcUrl(url);
config.setUsername(username);
config.setPassword(password);
config.setMaximumPoolSize(MENTIONED_TOTAL_CONNECTIONS);
// Like this you can configure multiple properties here
HikariDataSource dataSource = new HikariDataSource(config);
return dataSource;
}
DataSource dataSource = createCustomConnection(...) // Pass Parameters here
Here you have created the datasource that creates a single connection at the same time.
for more information https://github.com/brettwooldridge/HikariCP#initialization
Thank you.

You can try setting the minimumIdle property. By default it is set to maxPoolSize, so 10 connections are created initially. You can refer minimumIdle section in this link, https://github.com/brettwooldridge/HikariCP#frequently-used

Using DataSource with Transaction using Spring

I am working as part of a legacy j2ee application (plain application no Spring or Hibernate support)
The application exposes the following method:
public DataSource getConnectionDataSource();
DataSource is properly initiated to a specific DB schema by the product.
When I want to query the DB I create a jdbcTemplate object and query the like so:
MapSqlParameterSource parameters = new MapSqlParameterSource();
parameters.addValue("PRINT_LOCA",printerLocation);
DataSource printersSchemaDS = context.getCommonServices().getConnectionDataSource("printersSchema");
NamedParameterJdbcTemplate jdbcTemplate = new NamedParameterJdbcTemplate(printersSchemaDS);
String printerId = jdbcTemplate.queryForObject("select printerId from printers where printer_location=:PRINT_LOCA ",parameters,String.class);
My question is how can I execute multiple Update SQL statements in a single transaction when I only have the DataSource object?
I see that there is TransactionTemplate in Spring, but is it possible to initialize it with DataSource object alone?
Thank you!

Try to take single connection from datasource, then use ordinary manual jdbc transaction:
try (Connection con = datasource.getConnection();) {
con.setAutoCommit(false);
// insert logic
con.commit();
} catch (SQLException e) {
// handle exception
con.rollback();
}
Full example here:
https://docs.oracle.com/javase/tutorial/jdbc/basics/transactions.html

Create Entity Manger runtime with connection pooling in Spring and eclipse Link JPA

I am trying to create a entity manager at runtime which will have connection pooling.
Data base details will be provided by user and based on that we need to create one entity manager which will have connection pooling.
I am using spring MVC , Eclipse Link JPA.
I tried some solution but either they are working with #configuration annotation which is not ideal for me.
One solution is working fine but i am not able to maintain connection pooling.
below is code which is working fine but not able to add support for connection pooling.
public static EntityManager getEntityManager(){
EntityManagerFactory emf;
Map properties = new HashMap();
properties.put("eclipselink.jdbc.driver", "com.mysql.jdbc.Driver");
properties.put("eclipselink.jdbc.url", "jdbc:mysql://localhost:3306/SampleDB");
properties.put("eclipselink.jdbc.user", "root");
properties.put("eclipselink.jdbc.password", "root");
//emf = Persistence.createEntityManagerFactory("jpablogPUnit");
emf = Persistence.createEntityManagerFactory("datajpa",properties);
return (EntityManager) emf.createEntityManager();
}

Error while connecting Mysql db with java using hibernate

I was trying to connect a simple java application with mysql db using hibernate. I have already created the schema in my db and this java application is simply creating a table in this schema and inserting data in it.All the time I am getting same error.
My Code is as follows:
hibernate.cfg.xml
UserDetails.java
HibernateTest.java
Error:
Please help me, I have been stuck for quite a long time.
Thanks !!

Seems like a duplicate of Exception in thread "main" java.util.ServiceConfigurationError
Seems that your using hibernate >=4 and the setup procedure from hibernate <4.
Correct way according to the link is.
Configuration configuration = new Configuration().configure();
ServiceRegistryBuilder registry = new ServiceRegistryBuilder();
registry.applySettings(configuration.getProperties());
ServiceRegistry serviceRegistry = registry.buildServiceRegistry();
SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
Session session = sessionFactory.openSession();

//check External Jar files whether you added properly or not...if not remove all jar files and add once again...
After Main
Configuration cfg = new Configuration();
cfg.configure("hibernate.cfg.xml");
SessionFactory sf = cfg.buildSessionFactory();
Session session = sf.OpenSession();
UserDetails ud = new UserDetails();
ud.setName("bdskbf");
ud.setId(23);
Transaction tnx = session.beginTransaction();
session.save(ud);
tnx.getTransaction.commit();