struts2RestJpaBootstrap - dao

JpaBookDAO.java

package org.demo.vo.dao;

import java.util.ArrayList;
import java.util.List;

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

import org.apache.commons.lang3.StringUtils;
import org.demo.util.GenericJpaDao;
import org.demo.vo.bean.Book;

public class JpaBookDAO extends GenericJpaDao<Book, Integer> {

	private final static Predicate[] ap = {};
	
	/**
	 * Constructs a DAO for Book
	 */
	public JpaBookDAO() {
		super(Book.class);
	}
	
	/**
	 * Search by book example
	 */
	public List<Book> search(Book book) {
		final EntityManager em = getEntityManager();
		if ( book != null  ) {
			CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();
			CriteriaQuery<Book> criteriaQuery = criteriaBuilder.createQuery(Book.class);
			Root<Book> from = criteriaQuery.from(Book.class);
			
			List<Predicate> listP = new ArrayList<Predicate>();
			if (StringUtils.isNotBlank(book.getIsbn())) {
				Predicate predicate = criteriaBuilder.equal(from.get("isbn"), book.getIsbn());
				listP.add(predicate);
			}
			
			if (StringUtils.isNotBlank(book.getTitle())) {
				Predicate predicate = criteriaBuilder.equal(from.get("title"), book.getTitle());
				listP.add(predicate);
			}

			if (book.getId() != null) {
				Predicate predicate = criteriaBuilder.equal(from.get("id"), book.getId());
				listP.add(predicate);
			}

			if (book.getPublisherId() != null) {
				Predicate predicate = criteriaBuilder.equal(from.get("publisherId"), book.getPublisherId());
				listP.add(predicate);
			}

			if (book.getAuthorId() != null) {
				Predicate predicate = criteriaBuilder.equal(from.get("authorId"), book.getAuthorId());
				listP.add(predicate);
			}

			if (book.getPrice() != null) {
				Predicate predicate = criteriaBuilder.equal(from.get("price"), book.getPrice());
				listP.add(predicate);
			}

			if (book.getQuantity() != null) {
				Predicate predicate = criteriaBuilder.equal(from.get("quantity"), book.getQuantity());
				listP.add(predicate);
			}

			if (book.getDiscount() != null) {
				Predicate predicate = criteriaBuilder.equal(from.get("discount"), book.getDiscount());
				listP.add(predicate);
			}

			if (book.getAvailability() != null) {
				Predicate predicate = criteriaBuilder.equal(from.get("availability"), book.getAvailability());
				listP.add(predicate);
			}

			if (book.getBestSeller() != null) {
				Predicate predicate = criteriaBuilder.equal(from.get("bestSeller"), book.getBestSeller());
				listP.add(predicate);
			}
			
			criteriaQuery.where(listP.toArray(ap));
			TypedQuery<Book> tq = em.createQuery(criteriaQuery);
			return tq.getResultList();
		}
		else
		{
    		return this.loadAll();
		}
	}

}