package ejava.examples.daoex.dao;
   
   import java.util.List;
   
   import javax.persistence.EntityManager;
   
   import ejava.examples.daoex.bo.Book;
   
   /**
   * This class provides a simple DAO implementation based on JPA
   */
  public class JPABookDAOImpl implements BookDAO {
  	private EntityManager em;
  	
  	public void setEntityManager(EntityManager em) {
  		this.em = em;
  	}
  
  	@Override
  	public Book create(Book book) {
  		em.persist(book);
  		return book;
  	}
  
  	@Override
  	public Book update(Book book) {
  		return em.merge(book);
  	}
  
  	@Override
  	public Book get(long id) {
  		return em.find(Book.class, id);
  	}
  
  	@Override
  	public void remove(Book book) {
  		em.remove(book);
  	}
  
  	@Override
  	public List<Book> findAll(int offset, int limit) {
  		return em.createQuery("select b from Book b", Book.class)
  				.setFirstResult(offset)
  				.setMaxResults(limit)
  				.getResultList();
  	}
  
  }