Overview

Registering subtypes without annotating the parent class, see this.

Implementation on SPI.

Usage

Maven dependencies

<dependency>
    <groupId>io.github.black-06.jackson</groupId>
    <artifactId>jackson-modules-dynamic-subtype</artifactId>
    <version>2.14.0</version>
</dependency>

Registering modules.

ObjectMapper mapper = new ObjectMapper().registerModule(new DynamicSubtypeModule());

Alternatively, you can also auto-discover these modules with:

ObjectMapper mapper = new ObjectMapper().findAndRegisterModules();

Ensure that the parent class has at least the JsonTypeInfo annotation.

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type")
public interface Parent {
}

Add the JsonSubType annotation to your subclass.

import io.github.black.jackson.JsonSubType;

@JsonSubType("first-child")
public class FirstChild {
    // ...
}

SPI: Put the subclasses in the META-INF/services directory under the interface. Example: META-INF/services/package.Parent

package.FirstChild

Alternatively, you can also use the auto-service to auto-generate these files:

import io.github.black.jackson.JsonSubType;
import com.google.auto.service.AutoService;

@AutoService(Parent.class)
@JsonSubType("first-child")
public class FirstChild {
    // ...
}

Done, enjoy it.

More

I rewrote the ServiceLoader, it only returns class instead of instance. It comes from Oracle JDK 8. I mean, this module may NOT WORK in other jdk version.

Try this if it doesn't work: new DynamicSubtypeModule().setUseStandardServiceLoader(true);