Java Jackson将子JSON反序列化为父属性
这是我的要求。我有下面的POJOJava Jackson将子JSON反序列化为父属性,java,json,jackson,mapping,parent-child,Java,Json,Jackson,Mapping,Parent Child,这是我的要求。我有下面的POJO class Car { private String brandName; private String color; private Model model; } class Model { private String modelName; private String year; } 如果我得到如下所示的输入json,那么它应该反序列化并映射到这两个类 String json = "{\"brandName\" : \"Toyoto\"
class Car {
private String brandName;
private String color;
private Model model;
}
class Model {
private String modelName;
private String year;
}
如果我得到如下所示的输入json,那么它应该反序列化并映射到这两个类
String json = "{\"brandName\" : \"Toyoto\", \"color\" : \"Silver\", \"model\" : {\"modelName\": \"Corolla\", \"year\": \"2019\"}}"
ObjectMapper mapper = new ObjectMapper();
Car car = mapper.readValue(json, Car.class);
assertEquals("Corolla", car.getModel().getModelName());
这个案子没问题
但若我传递子json,那个么在不改变映射类的情况下也应该可以工作
String json = "{\"modelName\": \"Corolla\", \"year\": \"2019\"}"
ObjectMapper mapper = new ObjectMapper();
Car car = mapper.readValue(json, Car.class);
assertEquals("Corolla", car.getModel().getModelName());
任何解决此问题的方法您都可以为汽车类实现自定义反序列化器,如:
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
import java.io.IOException;
/**
* @author Ehsan Zaery Moghaddam
*/
public class CarDeserializer extends StdDeserializer<Car> {
public CarDeserializer() {
this(null);
}
public CarDeserializer(Class<?> vc) {
super(vc);
}
@Override
public Car deserialize(JsonParser jp, DeserializationContext dctx)
throws IOException, JsonProcessingException {
JsonNode node = jp.getCodec().readTree(jp);
Car c = new Car();
Model cModel = new Model();
if(node.has("brandName")) {
// the JSON string contains both car and model details
c.setBrandName(node.get("brandName").asText());
c.setColor(node.get("color").asText());
JsonNode modelNode = node.get("model");
cModel.setModelName(modelNode.get("modelName").asText());
cModel.setYear(modelNode.get("year").asText());
} else {
// the JSON string just has model details
cModel.setModelName(node.get("modelName").asText());
cModel.setYear(node.get("year").asText());
}
c.setModel(cModel);
return c;
}
}
这不需要更改您的POJO。但是,如果可以这样做,您可以选择在POJO类中使用注释注册自定义反序列化程序,如下所示:
@JsonDeserialize(using = CarDeserializer.class)
public class Car { ... }
感谢您的代码,尽管我之前考虑过这种方法,但我正在寻找一些更简单的方法,否则我需要像上面那样有许多自定义实现。
@JsonDeserialize(using = CarDeserializer.class)
public class Car { ... }