I want to configure a Jackson deserializer that act differently depending on the target type of the annotated field.
public class Car {
@JsonSerialize(using=IdSerializer.class)
@JsonDeserialize(using=IdDeserializer.class)
String id
}
public class Bus {
@JsonSerialize(using=IdSerializer.class)
@JsonDeserialize(using=IdDeserializer.class)
Id id
}
Jackson serializers know the type from which it is converting data, so this is working:
public class IdSerializer extends JsonSerializer<Object> {
@Override
public void serialize(Object value, JsonGenerator jsonGen, SerializerProvider provider) throws IOException {
// value is the annotated field class
if(value instanceof String)
jsonGen.writeObject(...);
else if (value instanceof Id)
jsonGen.writeObject(...);
else
throw new IllegalArgumentException();
}
}
Jackson deserializers seem to do not know the target type into which it will convert data:
public class IdDeserializer extends JsonDeserializer<Object> {
@Override
public Object deserialize(JsonParser jp, DeserializationContext context) throws IOException {
// what is the annotated field class?
}
}
In the serializer, you could add extra information about the type that will help you during deserialization.
Building from your posted IdSerializer...
public class IdSerializer extends JsonSerializer<Object> {
@Override
public void serialize(Object value, JsonGenerator jsonGen, SerializerProvider provider) throws IOException {
// value is the annotated field class
if(value instanceof String){
jsonGen.writeStartObject();
jsonGen.writeFieldName("id");
jsonGen.writeObject(value);
jsonGen.writeFieldName("type");
jsonGen.writeString("String");
jsonGen.writeEndObject();
}
else if (value instanceof Id){
Id id = (Id) value;
jsonGen.writeStartObject();
jsonGen.writeFieldName("id");
jsonGen.writeString(id.getStuff());
jsonGen.writeFieldName("type");
jsonGen.writeString("Id");
jsonGen.writeEndObject();
}
else{
throw new IllegalArgumentException();
}
}
}
In your deserializer, you can parse this 'type' field and return an Object of the proper type.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.