Question

我有一个EmebeddedId的实体。正在按预期触发实体监听器（在加载时修剪Strings关闭空白）实体监听器，ID Embeddable上的同一监听器根本不会被触发。

我做错了吗？如何解决？

实体：

@Entity
@Table(name = "SUBMITTER_VIEW")
@EntityListeners(TrimListener.class)
public class Submitter implements Serializable {

    private static final long serialVersionUID = 1L;

    @EmbeddedId
    private SubmitterPK id;

    @Trim
    @Column(name = "DOC_NAME")
    private String name;
...

嵌入式：

@Embeddable
@EntityListeners(TrimListener.class)
public class SubmitterPK implements Serializable {

    private static final long serialVersionUID = 1L;

    @Column(name = "LSTORT")
    private String bsnr;

    @Trim
    @Column(name = "LOGIN")
    private String login;
...

监听器：

public class TrimListener {

    Logger log = LoggerFactory.getLogger("TrimListener");

    @PostLoad
    public void repairAfterLoad(final Object entity) throws IllegalAccessException {

        log.debug("trimlistener active");

        final Set<Field> trimProps = getTrimProperties(entity.getClass());

        for (final Field fieldToTrim : trimProps) {
            final String propertyValue = (String) fieldToTrim.get(entity);
            if (propertyValue != null) {
                fieldToTrim.set(entity, propertyValue.trim());
            }
        }
    }
...

Answer 1

我认为它显然被忽略了，因为它不是JPA 2.0所期望的标准场所。根据JPA 2.0最终规范，实体监听器可以是实体，映射的超类或与其中一个相关联的监听器（参见规范的第3.5节）：

可以将方法指定为生命周期回调方法，以接收实体生命周期的通知事件。可以在实体类，映射的超类或实体上定义生命周期回调方法与实体或映射的超类相关联的侦听器类

Answer 2

我已经调整了EntityListener，以递归方式跟随使用Embeddable注释的字段。现在，如果实体使用侦听器，则也会处理所有嵌入的类：

public class TrimListener {

    @PostLoad
    public void trimAfterLoad(final Object entity) throws IllegalAccessException {

        final Set<Trimmable> trimProps = getTrimProperties(entity);

        for (final Trimmable trimmable : trimProps) {
            final String propertyValue = (String) trimmable.field.get(trimmable.target);
            if (propertyValue != null) {
                trimmable.field.set(trimmable.target, propertyValue.trim());
            }
        }
    }

    private Set<Trimmable> getTrimProperties(final Object entity) throws IllegalAccessException {

        final Class<?> entityClass = entity.getClass();
        final Set<Trimmable> propertiesToTrim = new HashSet<Trimmable>();

        for (final Field field : entityClass.getDeclaredFields()) {
            if (field.getType().equals(String.class) && (field.getAnnotation(Trim.class) != null)) {
                field.setAccessible(true);
                propertiesToTrim.add(new Trimmable(entity, field));
                // if the entity contains embeddables, propagate the trimming
            } else if (field.getType().getAnnotation(Embeddable.class) != null) {
                field.setAccessible(true);
                propertiesToTrim.addAll(getTrimProperties(field.get(entity)));
            }
        }
        return propertiesToTrim;
    }

    private class Trimmable {

        final Object target;
        final Field field;

        public Trimmable(final Object target, final Field field) {
            this.target = target;
            this.field = field;
        }
    }
}

如何在Embeddable上触发EntityListener

2 个答案: