DatabaseWrapper.java 文件源码

/**
 * @return A list of all elements of the requested entity class
 */
// NOTE: this method is probably not a great idea to use for giant tables
@Nonnull
@CheckReturnValue
//returns a list of sauced entities
public <E extends SaucedEntity<I, E>, I extends Serializable> List<E> loadAll(@Nonnull final Class<E> clazz)
        throws DatabaseException {
    final EntityManager em = this.databaseConnection.getEntityManager();
    try {
        final String query = "SELECT c FROM " + clazz.getSimpleName() + " c";
        em.getTransaction().begin();
        final List<E> queryResult = em
                .createQuery(query, clazz)
                .getResultList();
        em.getTransaction().commit();
        return queryResult
                .stream()
                .map(s -> s.setSauce(this))
                .collect(Collectors.toList());
    } catch (final PersistenceException e) {
        final String message = String.format("Failed to load all %s entities on DB %s",
                clazz.getName(), this.databaseConnection.getName());
        throw new DatabaseException(message, e);
    } finally {
        em.close();
    }
}