包含在注释中时,@ JsonSerialize和@JsonDeserialize无法正常工作

时间:2019-07-02 13:35:33

标签: java spring-boot serialization jackson serializer

我试图创建一个自定义批注,以始终在给定属性进行批注时将其标记化,因此我具有以下结构:

@JsonComponent
public class TokenSerializer {

    @JsonSerialize(using = IdToTokenSerializer.class) // This does not work 
    @JsonDeserialize(using = TokenToIdDeserializer.class) // This does not work 
    @Retention(RetentionPolicy.RUNTIME)
    public static @interface TokenizedId {
        Class<?> value();
    }

    public static class IdToTokenSerializer extends JsonSerializer<Long> implements ContextualSerializer {
        ...
    }

    public static class TokenToIdDeserializer extends JsonDeserializer<Long> implements ContextualDeserializer {
        ...
    }
}

我为什么要那样使用?因为@TokenizedId将提供一个类,有条件地将在序列化器/反序列化器上考虑该类以执行某些操作。使用ContextualDeserializer配置此值,并从@TokenizedId获取类。

问题是,当我这样注释时,序列化程序和反序列化程序都无法工作:

@TokenizedId(MyClass.class)
private Long id;

但是当我这样使用它们(从@JsonSerialize移除@JsonDeserialize@TokenizedId时,它们起作用了)

@JsonSerialize(using = IdToTokenSerializer.class)
@JsonDeserialize(using = TokenToIdDeserializer.class)
@TokenizedId(MyClass.class)
private Long id;

我个人不喜欢这种方法,因为当开发人员想要对某些id进行标记时,他们将始终需要记住使用这三个注释,而且我希望@TokenizedId始终与这些序列化程序相关

在另一个注释上注释时,有没有办法使序列化器/反序列化器正常工作?

1 个答案:

答案 0 :(得分:1)

我能够使注释按我想要的方式工作,在查看Jackson图书馆的一些线索后,我发现了@JacksonAnnotationsInside注释:

/**
 * Meta-annotation (annotations used on other annotations)
 * used for indicating that instead of using target annotation
 * (annotation annotated with this annotation),
 * Jackson should use meta-annotations it has.
 * This can be useful in creating "combo-annotations" by having
 * a container annotation, which needs to be annotated with this
 * annotation as well as all annotations it 'contains'.
 * 
 * @since 2.0
 */
@Target({ElementType.ANNOTATION_TYPE})
@Retention(RetentionPolicy.RUNTIME)
@JacksonAnnotation
public @interface JacksonAnnotationsInside
{

}

在我的注释中包括此内容可以解决此问题:

@JacksonAnnotationsInside
@JsonSerialize(using = IdToTokenSerializer.class) 
@JsonDeserialize(using = TokenToIdDeserializer.class)
@Retention(RetentionPolicy.RUNTIME)
public static @interface TokenizedId {
    Class<?> value();
}