---

title: Java sidebar_position: 2 id: java license: | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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.