oracle - Hibernate自定义类型映射设置字符长度

Question

我目前正在 hibernate 中实现自定义类型映射(将 UUID 映射到 char 以便在 oracle 中设置索引)。我实现了 hibernate 类型 UUIDType 和 UUIDJavaDescriptor 并通过 @TypeDef 将它们添加到我们的 baseEntity (JPAEntity)。问题是列生成为 varchar(255) 而不是 varchar(36)。通过 @Column(length = 36,/* ... */) 注释 UUID 字段按预期工作，但我不想注释项目中的所有 UUID 字段。有谁知道全局调整所有 UUID 字段长度的方法吗？

public class UUIDType extends AbstractSingleColumnStandardBasicType<UUID> {
  public static final UUIDType INSTANCE = new UUIDType();
  public static final String NAME = "uuid";
  public static final Size SIZE = new Size(0, 0, 36, Size.LobMultiplier.NONE);
  // define the column size                      ^^^

  public UUIDType() {
    super(VarcharTypeDescriptor.INSTANCE, UUIDJavaDescriptor.INSTANCE);
  }

  @Override
  public String getName() {
    return NAME;
  }

  // Override size related methods
  @Override
  protected Size getDictatedSize() {
    return SIZE;
  }

  @Override
  public Size[] dictatedSizes(Mapping mapping) throws MappingException {
    return new Size[] { SIZE };
  }

  @Override
  public Size[] defaultSizes(Mapping mapping) throws MappingException {
    return new Size[] { SIZE };
  }
}

public class UUIDJavaDescriptor extends AbstractTypeDescriptor<UUID> {
  public static final UUIDJavaDescriptor INSTANCE = new UUIDJavaDescriptor();

  public UUIDJavaDescriptor() {
    super(UUID.class, ImmutableMutabilityPlan.INSTANCE);
  }

  @Override
  public UUID fromString(String string) {
    if (StringUtils.isEmpty(string)) return null;
    return UUID.fromString(string);
  }

  @Override
  public <X> X unwrap(UUID value, Class<X> type, WrapperOptions options) {
    if (value == null) {
      return null;
    }

    if (String.class.isAssignableFrom(type)) {
      return (X) toString(value);
    }

    throw unknownUnwrap(type);
  }

  @Override
  public <X> UUID wrap(X value, WrapperOptions options) {
    if (value == null) {
      return null;
    }

    if (String.class.isInstance(value)) {
      return UUID.fromString((String) value);
    }

    throw unknownWrap(value.getClass());
  }
}

@NoArgsConstructor
@EqualsAndHashCode(callSuper = true)
@Getter
@Setter
@ToString(callSuper = true)
@MappedSuperclass
@Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
@TypeDefs({
  @TypeDef(typeClass = UUIDType.class, defaultForType = UUID.class, name = UUIDType.NAME)
})
public abstract class JPAEntity {
 // ...
}

技术细节:

• Apache Maven 3.6.3
• openjdk 11.0.2
• Hibernate-Core 5.4.30.Final

Answer 1

您不能更改它，因为值 255 来自 javax.persistence.Column 注释。 Hibernate 6.0 将正确处理此问题，但目前，您只需在所有位置设置长度即可。