java.md

Output Layout

For package addressbook, Java output is generated under:

• <java_out>/addressbook/
• Type files: AddressBook.java, Person.java, Dog.java, Cat.java, Animal.java
• Schema module: AddressbookForyModule.java

For schemas without a Java package, the schema module name is derived from the source file stem, for example main.fdl generates MainForyModule.java. Java import graphs cannot mix default-package schemas with named Java packages.

Type Generation

Messages generate Java classes with @ForyField, default constructors, getters/setters, and byte helpers:

public class Person {
    public static enum PhoneType {
        MOBILE,
        HOME,
        WORK;
    }

    public static class PhoneNumber {
        @ForyField(id = 1)
        private String number;

        @ForyField(id = 2)
        private PhoneType phoneType;

        public byte[] toBytes() { ... }
        public static PhoneNumber fromBytes(byte[] bytes) { ... }
    }

    @ForyField(id = 1)
    private String name;

    @ForyField(id = 8)
    private Animal pet;

    public byte[] toBytes() { ... }
    public static Person fromBytes(byte[] bytes) { ... }
}

Messages with evolving=false are generated with Java fixed-schema struct encoding.

Unions generate classes extending org.apache.fory.type.union.Union:

public final class Animal extends Union {
    public enum AnimalCase {
        DOG(1),
        CAT(2);
        public final int id;
        AnimalCase(int id) { this.id = id; }
    }

    public static Animal ofDog(Dog v) { ... }
    public AnimalCase getAnimalCase() { ... }
    public int getAnimalCaseId() { ... }

    public boolean hasDog() { ... }
    public Dog getDog() { ... }
    public void setDog(Dog v) { ... }
}

Schema Module

Each JVM schema generates a ForyModule. Imported schema modules are installed through fory.register(...), so shared imports are deduplicated by the Fory instance.

public final class AddressbookForyModule implements org.apache.fory.ForyModule {
  public static final AddressbookForyModule INSTANCE = new AddressbookForyModule();

  static ThreadSafeFory getFory() { ... }

  @Override
  public void install(Fory fory) {
    org.apache.fory.resolver.TypeResolver resolver = fory.getTypeResolver();
    resolver.registerUnion(Animal.class, 106L, new org.apache.fory.serializer.UnionSerializer(resolver, Animal.class));
    resolver.register(Person.class, 100L);
    resolver.register(Person.PhoneType.class, 101L);
    resolver.register(Person.PhoneNumber.class, 102L);
    resolver.register(Dog.class, 104L);
    resolver.register(Cat.class, 105L);
    resolver.register(AddressBook.class, 103L);
  }
}

For schemas without explicit [id=...], generated registration uses computed numeric IDs (for example from auto_id.fdl):

resolver.register(Status.class, 1124725126L);
resolver.registerUnion(Wrapper.class, 1471345060L, new org.apache.fory.serializer.UnionSerializer(resolver, Wrapper.class));
resolver.register(Envelope.class, 3022445236L);
resolver.registerUnion(Envelope.Detail.class, 1609214087L, new org.apache.fory.serializer.UnionSerializer(resolver, Envelope.Detail.class));
resolver.register(Envelope.Payload.class, 2862577837L);

If option enable_auto_type_id = false; is set, registration uses symbolic names:

resolver.register(Config.class, "myapp.models", "Config");
resolver.registerUnion(
    Holder.class,
    "myapp.models",
    "Holder",
    new org.apache.fory.serializer.UnionSerializer(resolver, Holder.class));

Usage

Person person = new Person();
person.setName("Alice");
person.setPet(Animal.ofDog(new Dog()));

byte[] data = person.toBytes();
Person restored = Person.fromBytes(data);

gRPC Service Companions

With --grpc, Java emits one <ServiceName>Grpc.java per service. It exposes SERVICE_NAME, service and method descriptors, <ServiceName>ImplBase, and async, blocking, and future stub factories. See Java gRPC for dependencies and server, client, and streaming usage.