How to retrieve data from database using spring jpa hibernate

1. Create a Specification which would construct a query to pull records from database for a particular jpa entity

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import org.springframework.data.jpa.domain.Specification;

public class TravelEntitySpecification {
        public static Specification<TravelEntity> filterTravelEntity(final String id,final String empId) {

              return new Specification<TravelEntity>() {
                      @Override
                      public Predicate toPredicate(Root<TravelEntity> root, CriteriaQuery<?> query,                                               CriteriaBuilder builder) {

                             Predicate predicate = builder.conjunction();
                             predicate = builder.and(predicate, builder.equal(root.<PK>get(Constant.STRING_ID).get(Constant.STRING_ID), id));

    predicate = builder.and(predicate, builder.equal(root.<PK>get(Constant.STRING_ID).get(Constant.DEFV201_empId), empId));

    return predicate;

   }

  };

 }

2. Create a  Repository interface as like below for the entity

 import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

public interface TravelEntityRepository  extends JpaRepository<TravelEntity, String>, JpaSpecificationExecutor<TravelEntity>{

}

3. Invoke the repository from the dao as like below

public class TravelDAO{
@Autowired
private TravelEntityRepository travelEntityRepository;

public List<TravelEntity> getTravelList(){
return travelEntityRepository.findAll(TravelEntitySpecification.filterTravelEntity("1","2"));
}

public TravelEntity getTravelData(){
return travelEntityRepository.findOne(TravelEntitySpecification.filterTravelEntity("2","2"));
}