JPABookService.java 文件源码

@Override
public List<Book> getBooksOfAuthorWithId(int id) {
    EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("pl.edu.bogdan.training.db.entity");
    EntityManager em = entityManagerFactory.createEntityManager();

    // begining of transaction
    em.getTransaction().begin();
    Author author = em.find(Author.class, id);
    System.out.println(author.toString());
    for (Book b : author.getBooks()) {
        System.out.println(b.toString());
    }
    return author == null ? new ArrayList<Book>() : author.getBooks();
}