使用 Java 中的 Jackson 处理 JSON 中的原始联合类型（反）序列化

Question

I know that there are a couple of questions around this topic already, but I still struggle to find a good solution for primitive types. I am trying to serialize and deserialize the following JSON data:

{
  "key": "key1"
  "value": "value1"
}

However, the value is a union type and could be either a boolean, a number or a string. So these are also valid inputs:

{
  "key": "key2"
  "value": true
}

and

{
  "key": "key3"
  "value": 3
}

What is the best way to serialize and deserialize this into a Java POJO? My approach looks like this (but obviously only works with string values)

@RequiredArgsConstructor
@Getter
@EqualsAndHashCode
public class Request {

    private final String key;

    private final String value;
}

@RequiredArgsConstructor
@Getter
@EqualsAndHashCode
public class Response {

    private final String key;

    @JsonInclude(JsonInclude.Include.NON_NULL)
    private final String value;
}

Answer 1

Solved it this way.

@RequiredArgsConstructor
@Getter
@EqualsAndHashCode
public class Request {

    private final String key;

    @JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, property = "valueClass")
    private final String value;

    private final String valueClass;
}

@RequiredArgsConstructor
@Getter
@EqualsAndHashCode
public class Response {

    private final String key;

    @JsonInclude(JsonInclude.Include.NON_NULL)
    @JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, property = "valueClass")
    private final String value;

    @JsonIgnore
    private final String valueClass;
}