Java 在缺少字段时使用Jackson With Options生成Optional.Empty()

我正在使用Jackson将json字符串转换为Java对象.我班上有一门选修课.每当我试图反序列化缺少可选字段的字符串时，它为该字段生成null而不是Optional.empty().

下面是代码:

public class Main {
    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();
        mapper.registerModule(new Jdk8Module());
        Person1 p1 = mapper.readValue("{\"name\": \"harsh\"}", Person1.class);
        System.out.println(p1);
    }
}

@EqualsAndHashCode
@ToString
@Getter
@Builder
@NoArgsConstructor(force = true)
public class Person1 {
    public final String name;
    public final Optional<Integer> age;

    public Person1(String name, Optional<Integer> age) {
        this.name = name;
        this.age = age;
    }
}

它会生成以下输出:

Person1(name=harsh, age=null)

然而，我希望它能产生:

Person1(name=harsh, age=Optional.empty)

我还try 添加了OptionalIntegerDeserializer个客户反序列化程序，如下所示，但似乎不起作用:

public class Person1 {
    public final String name;
    @JsonDeserialize(using = OptionalIntegerDeserializer.class)
    public final Optional<Integer> age;

    public Person1(String name, Optional<Integer> age) {
        this.name = name;
        this.age = age;
    }

    public static class OptionalIntegerDeserializer extends StdDeserializer<Optional<Integer>> {
        public OptionalIntegerDeserializer() {
            super(Optional.class);
        }

        @Override
        public Optional<Integer> deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
            JsonNode node = p.readValueAsTree();
            if (node.isNull()) {
                return Optional.empty();
            } else {
                return Optional.of(node.intValue());
            }
        }
    }
}

有没有办法为缺失的字段生成Optional.empty而不是null？