Hibernate 4 migration tips

I was migrating the spring and hibernate in my application and found couple of issues. 

The hibernate 3.2.5 was not working with the old configuration methods.

With all the dependencies I got a null pointer exception 




java.lang.NullPointerException at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:207) at org.hibernate.service.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:75)

The above  exception message can be resolved by adding below in Hibernate property:

<property name="hibernate.temp.use_jdbc_metadata_defaults">false</property>

For developing a standalone hibernate code to ensure the entity works with the web application we can have a utility class with main method and make the changes.

hbm.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-mapping PUBLIC

      "-//Hibernate/Hibernate Mapping DTD //EN"

          "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-configuration>

    <session-factory>

       <property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>

       <property name="hibernate.connection.username">schemaname</property> 

       <property name="hibernate.connection.password">password</property>

       <property name="hibernate.connection.url">jdbc:oracle:thin:@database.com:port:databasename </property>

      <property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>

      <property name="connection.pool_size">1</property>

      <property name="show_sql">true</property>

      <property name="hibernate.temp.use_jdbc_metadata_defaults">false</property>

      <property name="hibernate.format_sql">false</property>

    </session-factory>

</hibernate-configuration>

public class HibernateUtil {

private static final SessionFactory sessionFactory;

static {

  //above config location - if present outside the class path, we use this file in the configuration object

        File f = new File("C:\\hibernate.cfg.xml");

        String xmlFile = "C:\\resources\\hibernate.query.xml";

//Add file that has the named query - use the addFile chaining method in configuration object.

//1. create a configuration object

Configuration config= new Configuration().configure(f);

config.addAnnotatedClass(Entity1.class)

.addAnnotatedClass(Entity2.class)

                .addFile(xmlFile);

//2. Create a service registry builder object and this needs to be attached to the config to get the session factory.

ServiceRegistryBuilder builder = new ServiceRegistryBuilder().applySettings(config.getProperties());

//3. buildSessionFactory expects a serviceRegistry object to create a session Factory

// the session object can be obtained from this sessionFactory - object factory.

sessionFactory = config.buildSessionFactory(builder.buildServiceRegistry());

}

public void main(String args[]){

  Session session = sessionFactory.openSession();

  Query query = session.createQuery("from entity1");

  List<Object> resobj = query.list();

  

//if we need to update the filter to the session use

 session.enableFilter("filterName");

 // Named Query

 Query query1 = session.getNamedQuery("QUERY_NAME_IN_XMLFILE");

List<Object> resobj1 = query1.list();

//if to execute the native SQL query and transform it to a entity within.

Query query2 = session.createSQLQuery("select * from ENTITY1_TABLE");

 query2.setResultTransformer(Transformers.aliasToBean(Entity1.class));

List<Entity1> resobj2 = query2.list();

}

}

//The above will execute and returns the results as expected.

Note: if there is a filter then we should use the enableFilter("name of filter")

if we have a parameterized filter we can set that using  session.enableFilter("name").setParameter("filterparam");