given a class, how to get the jackson structure of the class serialization?

Question

Given an arbitrary class, is it possible for Jackson to provide a list of the fields needed to serialize and deserialize it?

Jackson's serialization rules are complex. I'd like to determine at runtime what the Jackson JSON structure is expected for an arbitrary class (both serialization and deserialization). My current planned implementation is to look for an @JsonConstructor constructor method and parse its arguments. If that's not there, look for annotations on other methods, and otherwise, use the list of member variables. I'll recurse the algorithm for any non-primitive field types.

The end goal is to create documentation for service endpoints.

Answer 1

Yes, you can use Jackson's introspection. This has the benefit that all annotations are applied as expected, and result should be exactly as Jackson "sees" the type you want information about.

There are at least two ways to do that:

1. Request introspection via SerializationConfig (or, DeserializatonConfig), to get a BeanDescription
2. Use callback/visitor based approach by calling ObjectMapper.acceptJsonFormatVisitor(type, visitor)

First method is usually simpler:

JavaType type = mapper.constructType(MyBean.class);
BeanDescription desc = mapper.getSerializationConfig()
   .introspect(type);

but latter is useful for tasks like generation of schemas (JSON Schema, XML Schema, protoc, thrift).