java - Jackson 反序列化为默认子类型

Question

从 Location 扩展而来的 AddressLocation 和 AirportLocation 类。当 json 中的“type”字段作为“ADDRESS”或“AIRPORT”出现时，jackson 正确地将其分别反序列化为 AddressLocation 和 AirportLocation 类。当“类型”不存在时， jackson 不知道如何反序列化该对象。有没有一种方法可以配置 jackson ，如果“类型”不存在或为空，则使用默认类型作为“地址”？

//从以下内容中删除了 getter、setter 和构造函数

@JsonInclude(value= JsonInclude.Include.NON_EMPTY)
@JsonIgnoreProperties(ignoreUnknown = true)
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type", visible=false)
@JsonSubTypes({ 
        @JsonSubTypes.Type(value = AirportLocation.class, name = "AIRPORT"),
        @JsonSubTypes.Type(value = AddressLocation.class, name = "ADDRESS")
})

public abstract class Location {
    private List<Float> geoCoordinates;
    private String city;
    private String countryCode;  
}

public class AddressLocation extends Location {
    private String province;
    private String postalCode;
    private String streetAddress;

    public AddressLocation(final List<Float> geoCoordinates, final String city, final String countryCode,
                           final String province,
                           final String postalCode, final String streetAddress) {
        super(geoCoordinates, city, countryCode);
        this.province = province;
        this.postalCode = postalCode;
        this.streetAddress = streetAddress;
    }
}

public class AirportLocation extends Location {
 String airportCode;
}

我得到的错误是 -

Missing type id when trying to resolve subtype of [simple type, class ***]: missing type id property 'type'
 at [Source: (String)"{"geo_coordinates":[1.17549435E-38],"city":"Whateverville","country_code":"WW"}"; line: 1, column: 79]

Answer 1

当 JSON 由客户端发送并由 Controller 等框架反序列化时，我遇到了类似的问题。如果是这种情况，那是因为框架管理的 Jackson 不是由您的代码管理的。您可以通过注入(inject)自定义反序列化器，也可以通过传输对象简单地控制代码中的所有实例初始化

@POST
public String createAddress(AddressLocationRequest requestObj) {

   AddressLocation address = new AddressLocation();
   BeanUtils.copyProperties(address, requestObj);
   ...
}