Jackson Deserialize To Concrete Class Based On Type

Question

I have what I believe should be a simple use case.

I would like to serialize a POJO with type metadata (preferably a simple name I come up with, not the fully qualified class/package name), and later have Jackson deserialize the JSON back into the concrete class it came from by using this metadata. There is no inheritance hierarchy among classes being serialized and deserialized.

My scenario is I have a service which accepts multiple file types. For each file uploaded, the client can retrieve JSON data whose structure and type depends on the file it came from. Thus when I retrieve JSON from the service, it's not known what the concrete class is to deserialize to. I would like Jackson to figure this out based on metadata which it supplies.

For example, I'd like to be able to do this:

String json = ... // get JSON from the service
Object obj = mapper.readValue(json, Object.class) // concrete class is not known
System.out.println(obj.getClass()) // I want this to be MyConcreteClass.class

There is no inheritance hierarchy among JSON types returned.
I don't want to reveal package names or other internal service details/structure.
I have control over Jackson's serialization process

Relevant question: Can jackson determine root object type to deserialize to when json includes type property?

Thank you so much for your help!

score 1 · Answer 1 · answered Nov 12 '15 at 13:09

This can be achieved using Jackson's JavaType:

String className = "class.name.from.json.service";
JavaType dtoType = TypeFactory.defaultInstance().constructFromCanonical(className);
Object dto = new ObjectMapper().readValue(InputStream, dtoType);
assert dto.getClass().equals(dtoType.getRawClass());

Jackson Deserialize To Concrete Class Based On Type

1 Answers1