DatabaseWrapper.java 文件源码

/**
 * @return An entity if it exists in the database or null if it doesn't exist. If the entity is a SaucedEntity the
 * sauce will be set.
 */
@Nullable
@CheckReturnValue
public <E extends IEntity<I, E>, I extends Serializable> E getEntity(@Nonnull final EntityKey<I, E> entityKey)
        throws DatabaseException {
    final EntityManager em = this.databaseConnection.getEntityManager();
    try {
        em.getTransaction().begin();
        @Nullable final E result = em.find(entityKey.clazz, entityKey.id);
        em.getTransaction().commit();
        return setSauce(result);
    } catch (final PersistenceException e) {
        final String message = String.format("Failed to find entity of class %s for id %s on DB %s",
                entityKey.clazz.getName(), entityKey.id.toString(), this.databaseConnection.getName());
        throw new DatabaseException(message, e);
    } finally {
        em.close();
    }
}