解决Jackson YAML序列化中多态类型标签的显示问题

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLGenerator;
import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
import com.google.common.collect.ImmutableList;
import lombok.Value;

import java.util.List;
import static java.util.Objects.requireNonNull;

public class PolymorphicSerializationExample {

    @JsonTypeInfo(use = JsonTypeInfo.Id.NAME,
        include = JsonTypeInfo.As.EXISTING_PROPERTY,
        property = "type")
    @JsonSubTypes({
        @JsonSubTypes.Type(value = Car.class, name = "car"),
        @JsonSubTypes.Type(value = Truck.class, name = "truck") })
    public interface Vehicle {
        String getName();
    }

    @Value
    public static class Car implements Vehicle {
        String name;
        String type = "car"; // 类型信息作为现有属性

        @JsonCreator
        public Car(@JsonProperty("name") final String name) {
            this.name = requireNonNull(name);
        }
    }

    @Value
    public static class Truck implements Vehicle {
        String name;
        String type = "truck"; // 类型信息作为现有属性

        @JsonCreator
        public Truck(@JsonProperty("name") final String name) {
            this.name = requireNonNull(name);
        }
    }

    @Value
    public static class Vehicles {
        List<Vehicle> vehicles;

        @JsonCreator
        public Vehicles(@JsonProperty("vehicles") final List<Vehicle> vehicles) {
            super();
            this.vehicles = requireNonNull(vehicles);
        }
    }

    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper MAPPER = new ObjectMapper(); // JSON Mapper
        ObjectMapper YAML_MAPPER = YAMLMapper.builder()
            .disable(YAMLGenerator.Feature.WRITE_DOC_START_MARKER) // 禁用文档开始标记
            .build(); // YAML Mapper

        final Vehicles vehicles = new Vehicles(ImmutableList.of(new Car("Dodge"), new Truck("Scania")));

        // 序列化为JSON
        final String json = MAPPER.writerWithDefaultPrettyPrinter().writeValueAsString(vehicles);
        System.out.println("--- JSON Output ---");
        System.out.println(json);

        // 序列化为YAML
        final String yaml = YAML_MAPPER.writerWithDefaultPrettyPrinter().writeValueAsString(vehicles);
        System.out.println("\n--- YAML Output (Problematic) ---");
        System.out.println(yaml);
    }
}

--- JSON Output ---
{
  "vehicles" : [ {
    "name" : "Dodge",
    "type" : "car"
  }, {
    "name" : "Scania",
    "type" : "truck"
  } ]
}

--- YAML Output (Problematic) ---
vehicles:
- !<car>
  name: "Dodge"
  type: "car"
- !<truck>
  name: "Scania"
  type: "truck"

import com.fasterxml.jackson.dataformat.yaml.YAMLGenerator;
import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
import com.fasterxml.jackson.databind.ObjectMapper;
// ... 其他导入

public class PolymorphicSerializationExample {
    // ... Vehicle, Car, Truck, Vehicles 类定义

    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper MAPPER = new ObjectMapper();

        // 修正后的YAML Mapper配置
        ObjectMapper YAML_MAPPER = YAMLMapper.builder()
            .disable(YAMLGenerator.Feature.WRITE_DOC_START_MARKER)
            .disable(YAMLGenerator.Feature.USE_NATIVE_TYPE_ID) // 禁用原生类型ID特性
            .build();

        final Vehicles vehicles = new Vehicles(ImmutableList.of(new Car("Dodge"), new Truck("Scania")));

        final String json = MAPPER.writerWithDefaultPrettyPrinter().writeValueAsString(vehicles);
        System.out.println("--- JSON Output ---");
        System.out.println(json);

        final String yaml = YAML_MAPPER.writerWithDefaultPrettyPrinter().writeValueAsString(vehicles);
        System.out.println("\n--- YAML Output (Corrected) ---");
        System.out.println(yaml);
    }
}

--- JSON Output ---
{
  "vehicles" : [ {
    "name" : "Dodge",
    "type" : "car"
  }, {
    "name" : "Scania",
    "type" : "truck"
  } ]
}

--- YAML Output (Corrected) ---
vehicles:
- name: "Dodge"
  type: "car"
- name: "Scania"
  type: "truck"