如何使用Java和Jackson库反序列化Json字符串以获得多态结果？

Question

I've a class CONTAINER, that contains a List . BaseClass is not an abstract class, but there is 2 subtypes of BaseClass : BaseClassA and BaseClassB which each have extra fields.

BaseClass has an attribut enum Type, from which i can determinate if an object is BaseClass, BaseClassA or BaseClassB and that i want to use as a discriminator.

How can i tell Jackson the discriminator so when it deserialize the json string, it builds the correct object. At the moment every object is instancied as a BaseClass so i cannot cast it in my java code. The same way as @DiscriminatorFormula & @DiscriminatorValue work for hibernate and entities

I've found this question : How can I polymorphic deserialization Json String using Java and Jackson Library? which is kinda close but here the user only wants the basic type.

Answer 1

Guessing you have probably solved this but if not check out JsonTypeInfo as a way to annotate classes with subtypes for desrialization. This link http://programmerbruce.blogspot.com/2011/05/deserialize-json-with-jackson-into.html has a good explanation that is still valid. If you can't annotate your classes you can use configuration to set up mix-ins (see https://github.com/FasterXML/jackson-docs/wiki/JacksonMixInAnnotations ) that allow you to add annotations to existing classes.