Showing posts with label onDelete. Show all posts
Showing posts with label onDelete. Show all posts

Saturday, May 3, 2014

Hibernate Interceptor Example

In order to use an Interceptor with our Session, we need to create a class that extends EmptyInterceptor.. Create a new class with name DataInterceptor.java. And now paste the following code:
package com.pkm.commands;

import java.io.Serializable;
import java.util.Iterator;
import org.hibernate.EmptyInterceptor;
import org.hibernate.Transaction;

public class DataInterceptor  extends EmptyInterceptor {
    private int updates = 0;
    private int creates = 0;
    private int loads = 0;
    private int deletes = 0;
    
    @Override
    public boolean onSave(Object entity, Serializable id, Object[] state, String[] propertyNames, org.hibernate.type.Type[] types) {
        System.out.println("onSave");
        creates++;
        return true;
    }
    
    // called on load events
    @Override
    public boolean onLoad(Object entity, Serializable id, Object[] state, String[] propertyNames, org.hibernate.type.Type[] types) {
        System.out.println("onLoad");
        loads++;
        return true;
    }

    @Override
    public boolean onFlushDirty(Object entity, Serializable id, Object[] currentState, Object[] previousState, String[] propertyNames, org.hibernate.type.Type[] types) {
        System.out.println("onFlushDirty");
        updates++;
        return false;
    }

    @Override
    public void onDelete(Object entity, Serializable id, Object[] state, String[] propertyNames, org.hibernate.type.Type[] types) {
        System.out.println("onDelete");
        deletes++;
    }

    //called before commit into database
    @Override
    public void preFlush(Iterator iterator) {
        System.out.println("preFlush");
    } 

    //called after committed into database
    @Override
    public void postFlush(Iterator iterator) {
        System.out.println("postFlush");
    }
    
    @Override
    public void afterTransactionCompletion(Transaction tx) {
        if ( tx.wasCommitted() ) {
            System.out.println("Creations: " + creates + ", Updates: " + 
                    updates + ", Loads: " + loads + ", Deletes: " + deletes);
        }
    }
}

These are the most basic methods that an Interceptor implements:
  • onSave : Called when you save an object. The object is not persisted yet.
  • onFlushDirty : Called when you update an object. The object is not persisted yet.
  • onLoad: Called when you read an object from database.
  • onDelete : Called when you delete an object. The object is not deleted from the database yet.
  • preFlush : Called before committing to the database.
  • postFlush :  Called after committing to the database.

We should also update HibernateUtil class:


package com.pkm.utils;

import com.pkm.commands.DataInterceptor;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistryBuilder;

public class HibernateUtil {
    private static final SessionFactory sessionFactory = buildSessionFactory();
    private static ServiceRegistry serviceRegistry;
    
    private static SessionFactory buildSessionFactory() {
        try {
            Configuration configuration = new Configuration().setInterceptor(new DataInterceptor());
            configuration.configure();
            serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry(); 
            return configuration.buildSessionFactory(serviceRegistry);
        } catch (Exception ex) {
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }
 
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    public static void shutdown() {
        // Close caches and connection pools
        getSessionFactory().close();
    }
}

Now create main java class file to test the Interceptor.


package com.pkm.commands;

import com.pkm.domains.User;
import com.pkm.utils.HibernateUtil;
import org.hibernate.Session;
import org.hibernate.Transaction;

public class TestInterceptor {
    @SuppressWarnings("unchecked")
    public static void main(String[] args) {
        Session session = null;
     Transaction transaction = null;
        try {
            session = HibernateUtil.getSessionFactory().openSession();
            transaction = session.beginTransaction();

            User user = new User(System.currentTimeMillis() + "@gmail.com", "Pritom", "Kumar Mondal");
            session.save(user);
            Long firstId = user.getId();

            user = new User(System.currentTimeMillis() + "@gmail.com", "Pritom", "Kumar Mondal");
            session.save(user);
            Long secondId = user.getId();
            
            user = (User) session.get(User.class, firstId);
            user.setFirstName("First name changed");
            session.save(user);
            
            user = (User) session.get(User.class, secondId);
            session.delete(user);
            
            user = (User) session.get(User.class, Long.parseLong("10"));
            user = (User) session.get(User.class, Long.parseLong("11"));
            user = (User) session.get(User.class, Long.parseLong("12"));
            
            transaction.commit();
        } catch (Exception ex) {
            if(transaction != null) {
                transaction.rollback();
            }
            System.err.println(ex.getMessage());
        } finally {
            if(session != null) {
                session.close();
            }
        }
    }
}

Output of Example:


onSave
Hibernate: insert into User (email, first_name, last_name) values (?, ?, ?)
onSave
Hibernate: insert into User (email, first_name, last_name) values (?, ?, ?)
onDelete
Hibernate: select user0_.id as id0_0_, user0_.email as email0_0_, user0_.first_name as first3_0_0_, user0_.last_name as last4_0_0_ from User user0_ where user0_.id=?
onLoad
Hibernate: select user0_.id as id0_0_, user0_.email as email0_0_, user0_.first_name as first3_0_0_, user0_.last_name as last4_0_0_ from User user0_ where user0_.id=?
onLoad
Hibernate: select user0_.id as id0_0_, user0_.email as email0_0_, user0_.first_name as first3_0_0_, user0_.last_name as last4_0_0_ from User user0_ where user0_.id=?
onLoad
preFlush
onFlushDirty
Hibernate: update User set email=?, first_name=?, last_name=? where id=?
Hibernate: delete from User where id=?
postFlush
Creations: 2, Updates: 1, Loads: 3, Deletes: 1

Download complete example