BusinessLogic.java

// Part of your business logic code (using JPA). In this case, 'entityClass' is @Entity class, 
// and 'restrictions' is list of org.dynamicfinder.Restriction instance passed from 
// contoller/presesentation layer.
QueryBuilder queryBuilder = new JpaQueryBuilder(entityClass).where(restrictions);

// What we really need is query string based on restriction defined in 
// controller.
final String queryString = queryBuilder.getQueryString();
final String countQueryString = queryBuilder.getCountQueryString();

// Use parsed queryString as plain JPQL to EntityManager#createQuery() method.
final TypedQuery<E> query = this.entityManager.createQuery(queryString, entityClass);
final TypedQuery<Long> countQuery = this.entityManager.createQuery(countQueryString, Long.class);

// Now, JPA need to know about which parameter should be added to their 
// Query object. Luckily, dynamicfinder provide a way for this easily:
final Map<Integer, Restriction> actualRestriction = queryBuilder.getActualRestrictions();

for (final Integer parameter : actualRestriction.keySet()) {
	query.setParameter(parameter, actualRestriction.get(parameter).getValue());
	countQuery.setParameter(parameter, actualRestriction.get(parameter).getValue());
}