Support JSON binding with the JDK's built-in JSON API (`jdk.incubator.json`)

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Evaluación

Dificultad
5/5
Tiempo estimado
Más de una semana
Aptitud para principiantes
25/100
Tipo de issue
Nueva funcionalidad
Claridad
Bastante claro
Estado de actividad
Activo
Stack tecnológico
java, json
Área
api, backend-api-design

Línea de trabajo

Read the linked proposal and inspect the prototype’s JsonRecordHttpMessageConverter to understand the proposed mapping and constraints. Compare the reflection, generated, hybrid, and tree-only options for spring-web and spring-messaging; done means the project has a decided scope and approach, or has explained why this belongs in a separate library.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

status: waiting-for-triage
Use case

I want to build Spring MVC REST endpoints that read and write Java records as JSON without a third-party JSON library:

@PostMapping("/hello")
public HelloResponse hello(@RequestBody HelloRequest request) { ... }

The same records should also work as Kafka message payloads:

@KafkaListener(topics = "hello")
public void onHello(HelloRequest request) { ... }

JDK 28 ships an incubating JSON API (jdk.incubator.json) that parses JSON into a JsonValue tree and writes it back, but it does not map JSON to Java types.
Spring has HTTP and messaging converters for Jackson, Gson, JSON-B and Kotlin Serialization, but none for the JDK API.

Reasons for a JDK-only option:

  • Fewer dependencies for applications that only need simple JSON.
  • A smaller attack surface: jackson-databind has 86 advisories in OSV, 17 of them published in 2026.
  • GraalVM native images without reflection metadata for the JSON library.
What I have tried so far

A prototype on Spring Boot 4.1 / JDK 28-ea: https://github.com/drnow4u/springboot-jdk28-json

  • JsonRecordHttpMessageConverter, an AbstractHttpMessageConverter<Record> that maps JSON objects to and from records using reflection over record components (String, numeric and boolean types, nested records).
  • Malformed JSON or a wrong value type is mapped to HttpMessageNotReadableException (400).
  • The JDK parser has no size limits and repeats the offending input in its error messages, so the converter limits the body size (413) and shortens error messages.
  • Spring AOT already registers reflection hints for the records used in the controller signature, so option A below may work in a native image; this cannot be verified until GraalVM supports JDK 28.
Questions

The main design question is how the mapping should work:

  • A. Reflection over record components (what the prototype does). No setup, but needs AOT hints for native images.
  • B. Compile-time generated bindings (annotation processor), similar to Kotlin Serialization. No reflection, errors at compile time, but needs a processor on the build path.
  • C. Hybrid: generated bindings when present, reflection otherwise.
  • D. Tree types only: a converter for JsonValue / JsonObject / JsonArray, with mapping left to applications or libraries.

Whichever option is chosen, the mapping would be shared by an HttpMessageConverter (spring-web) and a MessageConverter (spring-messaging, used by @KafkaListener); a Kafka Serializer/Deserializer would belong in Spring for Apache Kafka.

Would the Spring team consider any of these for Spring Framework, and which one? Or should this live in a separate library until the JDK API leaves incubation?

The full proposal, covering security, performance, native image and open questions, is here:
https://github.com/drnow4u/springboot-jdk28-json/blob/main/docs/proposal-jdk-json-binding.md

Lenguaje dominante
Java
Estrellas
60.3k
Forks
38.7k
Merge medio
1 d 1 h
PR fusionados (30 d)
33

Preparar el entorno

Primeros pasos

  1. Lee el issue completo y luego la guía de contribución del proyecto.
  2. Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
  3. Haz un fork del repositorio y trabaja en una rama.
  4. Abre un pull request que haga referencia al número del issue.

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