如何将字符串列表反序列化为单个 arg 值 class？

Question

基本上我总是想将我的 Id class 解包到父对象，但是如果是 List<> 我不能使用 jackson 库中的 JsonUnwrapped Annotation。

@lombok.Value
public class Response {
  List<MyId> ids;
  // ... other fields
}

@lombok.Value
public class MyId {
  String id;
}

{
  "ids": ["id1", "id2"]
  "otherField": {}
}

Working solution with jackson-databind 2.11

@lombok.Value
public class MyId {
  @JsonValue
  String id;

  public MyId(final String id) {
    this.id = id;
  }
}

Answer 1

您可以使用 @JsonValue。来自 docs:

Marker annotation that indicates that the value of annotated accessor (either field or "getter" method [a method with non-void return type, no args]) is to be used as the single value to serialize for the instance, instead of the usual method of collecting properties of value. Usually value will be of a simple scalar type (String or Number), but it can be any serializable type (Collection, Map or Bean).

用法：

@Value
public class MyId {
    @JsonValue
    String id;
}

完整代码：

public class JacksonExample {

    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        List<MyId> myIds = new ArrayList<>();
        MyId id1 = new MyId("one");
        MyId id2 = new MyId("two");
        myIds.add(id1);
        myIds.add(id2);
        Response response = new Response(myIds, "some other field value");
        System.out.println(objectMapper.writeValueAsString(response));
    }
}

@Value
class Response {
    List<MyId> ids;
    String otherField;
}

@Value
class MyId {
    @JsonValue
    String id;
}

输出：

{
  "ids": [
    "one",
    "two"
  ],
  "otherField": "some other field value"
}

如何将字符串列表反序列化为单个 arg 值 class？

How to deserialize a List of String to a single arg value class?

java

jackson

deserialization

jackson-databind