Jackson 序列化:如何忽略超类属性

问题描述

我想序列化一个不受我控制的 POJO 类，但想避免序列化来自超类而不是来自最终类的任何属性.示例:

I want to serialize a POJO class which is not under my control, but want to avoid serializing any of the properties which are coming from the superclass, and not from the final class. Example:

public class MyGeneratedRecord extends org.jooq.impl.UpdatableRecordImpl<...>,
    example.generated.tables.interfaces.IMyGenerated {
  public void setField1(...);
  public Integer getField1();

  public void setField2(...);
  public Integer getField2();
...
}

从例子中可以猜到，这个类是由JOOQ生成的，继承自一个复杂的基类UpdatableRecordImpl，该类也有一些类似bean属性的方法，在序列化过程中会出现问题.此外，我有几个类似的类，因此最好避免为我生成的所有 POJO 复制相同的解决方案.

You can guess from the example that that this class is generated by JOOQ, and inherits from a complex base class UpdatableRecordImpl which also has some bean property-like methods, which cause problems during the serialization. Also, I have several similar classes, so it would be good to avoid duplicating the same solution for all of my generated POJOs.

到目前为止，我找到了以下可能的解决方案:

I have found the following possible solutions so far:

• 使用像这样的混合技术忽略来自超类的特定字段:如何告诉 jackson 忽略我无法控制源代码的属性?

这样做的问题是，如果基类发生变化(例如，其中出现了一个新的 getAnything() 方法)，它可能会破坏我的实现.

The problem with this is that if the base class changes (e.g., a new getAnything() method appears in it), it can break my implementation.

实现自定义序列化程序并在那里处理问题.这对我来说似乎有点矫枉过正.

implement a custom serializer and handle the issue there. This seems a bit overkill to me.

顺便说一下，我有一个接口，它准确地描述了我想要序列化的属性，也许我可以混合一个 @JsonSerialize(as=IMyGenerated.class) 注释......?我可以将其用于我的目的吗?

as incidentally I have an interface which describes exactly the properties I want to serialize, maybe I can mixin a @JsonSerialize(as=IMyGenerated.class) annotation...? Can I use this for my purpose?

但是，从纯设计的角度来看，最好能够告诉 jackson 我只想序列化最终类的属性，而忽略所有继承的属性.有没有办法做到这一点?

But, from pure design point of view, the best would be to be able to tell jackson that I want to serialize only the final class' properties, and ignore all the inherited ones. Is there a way to do that?

提前致谢.

推荐答案

您可以注册一个自定义的Jackson annotation introector 将忽略来自特定超类型的所有属性.下面是一个例子:

You can register a custom Jackson annotation intropector which would ignore all the properties that come from the certain super type. Here is an example:

public class JacksonIgnoreInherited {

    public static class Base {
        public final String field1;

        public Base(final String field1) {
            this.field1 = field1;
        }
    }

    public static class Bean extends Base {
        public final String field2;

        public Bean(final String field1, final String field2) {
            super(field1);
            this.field2 = field2;
        }
    }

    private static class IgnoreInheritedIntrospector extends JacksonAnnotationIntrospector {
        @Override
        public boolean hasIgnoreMarker(final AnnotatedMember m) {
            return m.getDeclaringClass() == Base.class || super.hasIgnoreMarker(m);
        }
    }

    public static void main(String[] args) throws JsonProcessingException {
        final ObjectMapper mapper = new ObjectMapper();
        mapper.setAnnotationIntrospector(new IgnoreInheritedIntrospector());
        final Bean bean = new Bean("a", "b");
        System.out.println(mapper
                        .writerWithDefaultPrettyPrinter()
                        .writeValueAsString(bean));
    }

}

输出:

{字段2":b"}

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