杰克逊的@JsonPropertyOrder 不适用于@JsonUnwrapped

Question

我有一个包含另一个对象属性的对象，如下所示：

import com.fasterxml.jackson.annotation.JsonPropertyOrder;
import com.fasterxml.jackson.annotation.JsonUnwrapped;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.Data;

@JsonPropertyOrder({"fA1","b","fA2"})
@Data
public class A {
    private String fA1;
    private String fA2;

    @JsonUnwrapped
    private B b = new B();

    @Data
    class B {
        private String fB1;
        private String fB2;
    }

    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        A a = new A ();
        System.out.println(objectMapper.writeValueAsString(a));
    }

}

我想要的是生成遵守此顺序的 json :

{
  "fA1":"",
  "fB1":"",
  "fA2":"",
  "fB2":""
}

有什么办法吗？

Answer 1

根据 this issue in the jackson-databind repository on GitHub, the @JsonPropertyOrder annotation doesn't work with @JsonUnwrapped 注释。请参阅下面的引用：

True, unwrapped properties are not included in ordering, since they are not really known by enclosing serializer as regular properties. And specifically, as things are, will be output as a block of properties per contained, so even if known they can not be reordered separately.

Perhaps something could be done with Jackson 3.x once we get there.

但您可以考虑 解决方法：因为您似乎正在使用 Lombok，您可以使用 @Delegate and @JsonIgnore:

注释 b

@Data
@JsonPropertyOrder({"fa1", "fb1", "fa2", "fb2"})
public class A {

    private String fA1;
    private String fA2;

    @Delegate
    @JsonIgnore
    private B b = new B();
}

@JsonIgnore 注释将确保 b 属性不被 Jackson 序列化。

并且 @Delegate 注释将告诉 Lombok 生成将调用转发给 B 方法的委托方法。这样，A class 将具有委托给 fB1 和 fB2 字段的 getter 和 setter 的 getter 和 setter。

杰克逊的@JsonPropertyOrder 不适用于@JsonUnwrapped

Jackson's @JsonPropertyOrder doesn't work with @JsonUnwrapped

java

json

orders