This is not a solution for every use case, in large part because the Reflections scan can take some time, but it's a pattern that may be generally applicable enough to describe in the documentation:
Define an annotation for the subtypes, and meta-annotate with @JsonTypeName:
@JsonTypeName
@Target({ElementType.ANNOTATION_TYPE, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface FoocorpJsonType {
}
Use @FoocorpJsonType on all subtypes to be registered with the mapper:
@FoocorpJsonType
public class ConcreteMessage extends AbstractMessage {}
In a suitable location (such as a @PostConstruct method on a Spring configuration class, or wherever the ObjectMapper is built), use the org.reflections:reflections package and this magic spell:
Reflections reflections = new Reflections(
ConfigurationBuilder.build("com.foocorp.base.package")
);
This will scan the classpath (limited for performance) for types annotated with the custom annotation and register them all with the mapper so they can be deserialized when seen.
This is not a solution for every use case, in large part because the Reflections scan can take some time, but it's a pattern that may be generally applicable enough to describe in the documentation:
Define an annotation for the subtypes, and meta-annotate with
@JsonTypeName
:Use
@FoocorpJsonType
on all subtypes to be registered with the mapper:In a suitable location (such as a
@PostConstruct
method on a Spring configuration class, or wherever theObjectMapper
is built), use theorg.reflections:reflections
package and this magic spell:mapper.registerSubtypes(reflections.getTypesAnnotatedWith(FoocorpJsonType.class).toArray(new Class[0]));