Spring &引用；org.hibernate.PersistentObject异常：分离实体；然后是应用程序崩溃

我正在尝试将此实体持久化：

@Entity
public class Produto extends Model {
  @Id
  @GeneratedValue(strategy=GenerationType.IDENTITY)
  private Integer id;
...
  @OneToMany
  @Fetch(FetchMode.SELECT)
  @Cascade(CascadeType.ALL)
  private List<Imagem> thumbnails;
...
}

服务

public void insert(E object) {
    dao.insert(object);
  }

dao

public void insert(E object) {
    EntityManager entityManager = getEntityManager();
        entityManager.getTransaction().begin();
        entityManager.persist(object);
        entityManager.getTransaction().commit();
    entityManager.close();
  }

属性编辑器

  @RequestMapping(value = "/insert", method=RequestMethod.POST)
  @ResponseBody
  @PreAuthorize("hasPermission(#user, 'cadastra_'+#this.this.name)")
  public void insert(@Valid E object, BindingResult result) {
    serv.insert(object);
  }

public class ImagemEditor extends PropertyEditorSupport {
  @Override
  public void setAsText(String text) {
    if (!text.equals("")) {
      Integer id = Integer.parseInt(text);
      ImagemService serv = new ImagemService();
      org.loja.AppContextHolder.getContext().getAutowireCapableBeanFactory().autowireBean(serv);
      Imagem imagem = serv.findBy("id", id);
      setValue(imagem);
    } else {
      setValue(null);
    }
  }
}

但我得到了这个错误：

org.hibernate.PersistentObjectException: detached entity passed to persist: org.loja.model.imagem.Imagem

当我尝试退出应用程序时（使用ctrl-c，我使用spring boot运行它），它会崩溃，并出现以下消息：

2019-11-18 19:55:46.244  INFO 134572 --- [       Thread-3] .SchemaDropperImpl$DelayedDropActionImpl : HHH000477: Starting delayed evictData of schema as part of SessionFactory shut-down'

直到我结束这个过程

---

任何人都可以提示这里出了什么问题？

我设法解决了这个问题，将属性配置更改为：

  @OneToMany(fetch = FetchType.EAGER)
  private Set<Imagem> thumbnails;

@OneToMany（fetch=FetchType.EAGER）
私人设置缩略图；

使用此html/thymeleaf代码：

  <table>
    <tr>
      <td>
        <button type="button" onclick="add_single_imagem();" th:style="${command.icone}? 'display: none;' : 'display: block;'">
          <img class="thumbnail" th:src="@{/images/icon_add_imagem.png}" alt="adicionar icone"/>
          <input type="file" accept="image/jpeg" class="image-uploader" id="thumbnails" style="display: none;" th:attr="data-target=${'thumbnails'}, data-url=@{/imagem/upload}, data-path=@{/imagem/download}" onchange="image_upload(this);"/>
        </button>
      </td>
      <td>
        <div class="gallery" id="gallery">
          <th:block th:each="img,stat : ${command.thumbnails}">
            <input type="hidden" th:field="*{thumbnails}" th:value="${img.id}"/>
            <img class="thumbnail" th:id="${'image_'+img.id}" th:src="@{/imagem/download/__${img.id}__}" th:alt="${command.nome}">
          </th:block>
        </div>
      </td>
    </tr>
  </table>

现在，该属性将与实体一起保留，不会出现问题

  <table>
    <tr>
      <td>
        <button type="button" onclick="add_single_imagem();" th:style="${command.icone}? 'display: none;' : 'display: block;'">
          <img class="thumbnail" th:src="@{/images/icon_add_imagem.png}" alt="adicionar icone"/>
          <input type="file" accept="image/jpeg" class="image-uploader" id="thumbnails" style="display: none;" th:attr="data-target=${'thumbnails'}, data-url=@{/imagem/upload}, data-path=@{/imagem/download}" onchange="image_upload(this);"/>
        </button>
      </td>
      <td>
        <div class="gallery" id="gallery">
          <th:block th:each="img,stat : ${command.thumbnails}">
            <input type="hidden" th:field="*{thumbnails}" th:value="${img.id}"/>
            <img class="thumbnail" th:id="${'image_'+img.id}" th:src="@{/imagem/download/__${img.id}__}" th:alt="${command.nome}">
          </th:block>
        </div>
      </td>
    </tr>
  </table>