Milos - Updates for new Criteria API

CustomerDAOImpl.java

package com.juratech.springdemo.dao;

import java.util.List;

import javax.persistence.TypedQuery;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

import com.juratech.springdemo.entity.Customer;

@Repository
public class CustomerDAOImpl implements CustomerDAO {

	//need to inject the session factory
	@Autowired
	private SessionFactory sessionFactory;
	
	@Override
	public List<Customer> getCustomers() {	
		return getCustomersBy("firstName");
	}
	
	

	@Override
	public void saveCustomer(Customer theCustomer) {
	// get current hibernate session
		Session currentSession = sessionFactory.getCurrentSession();
	//save the customer ... finally 
		currentSession.save(theCustomer);
		
	}

	public List<Customer> getCustomersBy(String theSortField) {
		
		Session currentSession = sessionFactory.getCurrentSession();
		
		//
		// Using new Criteria Query API
		// - docs: https://docs.oracle.com/javaee/7/tutorial/persistence-criteria.htm#GJITV
		// 
		//
		
		// Create CriteriaBuilder
		CriteriaBuilder builder = currentSession.getCriteriaBuilder();
		
		// Create CriteriaQuery
		CriteriaQuery<Customer> theCriteria = builder.createQuery(Customer.class);
		
		// For a particular CriteriaQuery object, the root entity of the query, 
		// from which all navigation originates, is called the query root. 
		// It is similar to the FROM clause in a JPQL query.
		//
		Root<Customer> customer = theCriteria.from(Customer.class);		
		theCriteria.select(customer);
		theCriteria.orderBy(builder.asc(customer.get(theSortField)));
		
		// create query based on criteria
		TypedQuery<Customer> query = currentSession.createQuery(theCriteria);
		
		// execute the query
		List<Customer> customers = query.getResultList();
		
		return customers;			
	}

}