Question

我想知道在从数据库中读取实体后是否有更好的方法来更新实体。

这似乎太多代码来完成一项简单的任务。我已经尝试使用em.merge（），它没有将数据持久存储到数据库中。

public class PodcastManager {

    private EntityManagerFactory emf;


    public PodcastManager(EntityManagerFactory emf) {
        this.emf = emf;
    }

    public void updatePodcast(Podcast podcast) {
        EntityManager em = emf.createEntityManager();
        em.getTransaction().begin();
        Podcast ptu = em.find(Podcast.class, podcast.getId());
        if ( ptu != null) {
            ptu.setTitle(podcast.getTitle());
            ptu.setDescription(podcast.getDescription());
            ptu.setUrl(podcast.getUrl());
            ptu.setLang(podcast.getLang());
            ptu.setCopyright(podcast.getCopyright());
            ptu.setItunesSubtitle(podcast.getItunesSubtitle());
            ptu.setItunesAuthor(podcast.getItunesAuthor());
            ptu.setItunesSummary(podcast.getItunesSummary());
            ptu.setItunesOwnerName(podcast.getItunesOwnerName());
            ptu.setItunesOwnerEmail(podcast.getItunesOwnerEmail());
            ptu.setItunesImageHREF(podcast.getItunesImageHREF());
            ptu.setExplicit(podcast.isExplicit());
        }
        em.getTransaction().commit();
        em.close();
    }
}

Answer 1

我设法让它合并工作如下。

public void updatePodcast(Podcast podcast) {
        EntityManager em = emf.createEntityManager();
        try {
            em.getTransaction().begin();
            em.merge(podcast);
            em.flush();

        } finally {
            em.getTransaction().commit();
            em.close();
        }
    }

带有EclipseLink Update Entity的Java SE JPA

1 个答案: