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title Java Serialization Guide
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id serialization_index
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.

Apache Fory™ Java provides high-performance binary object serialization, a cross-language random-access row format, and JSON serialization for Java. Binary serialization supports xlang mode for cross-language payloads and native mode for Java-only object graphs. Fory JSON is a high-performance JSON serialization framework for Java applications.

Choose a Format

Format Use it when Artifact Start here
Binary Object Serialization You need compact object graphs in Java native mode or across supported languages org.apache.fory:fory-core Basic Serialization
Row Format You need zero-copy random access, partial reads, or Arrow integration org.apache.fory:fory-format Row Format
Fory JSON You need high-throughput standard JSON for Java applications org.apache.fory:fory-json JSON Support

Binary Object Serialization

Features

  • Generated Codecs: JIT-generated serializers reduce virtual dispatch, branching, and metadata lookups on hot paths.
  • Native and Xlang Modes: Choose Java-native object semantics or a portable wire format shared with other Fory implementations.
  • Compact Encoding: Variable-length integers, metadata sharing, string compression, and optional numeric-array compression reduce payload size.
  • Object Graph Semantics: Preserve shared and circular references, polymorphism, schema evolution, and deep-copy identity.

Native Mode Features

  • Framework Replacement: Replace JDK serialization, Kryo, FST, Hessian, or Java-only Protocol Buffers payloads in Java-only systems.
  • JDK Semantics: Supports JDK custom serialization behavior and Externalizable in native mode.
  • Security Controls: Class registration, type checking, depth limits, and configurable deserialization policies protect decoding boundaries.

Installation

Add fory-core for binary object serialization. Keep all Fory modules in one application on the same version.

Maven

<!-- Binary object serialization -->
<dependency>
  <groupId>org.apache.fory</groupId>
  <artifactId>fory-core</artifactId>
  <version>1.4.0</version>
</dependency>

Gradle

// Binary object serialization
implementation("org.apache.fory:fory-core:1.4.0")

JDK 25 and Later

On JDK 25 and later, open java.lang.invoke to Fory. Use ALL-UNNAMED when Fory is on the classpath:

--add-opens=java.base/java.lang.invoke=ALL-UNNAMED

Use the Fory core module name when Fory is on the module path:

--add-opens=java.base/java.lang.invoke=org.apache.fory.core

Quick Start

Note that Fory creation is not cheap, the Fory instances should be reused between serializations instead of creating it every time. You should keep Fory as a static global variable, or instance variable of some singleton object or limited objects.

Single-Thread Usage

import java.util.List;
import java.util.Arrays;

import org.apache.fory.*;
import org.apache.fory.config.*;

public class Example {
  public static void main(String[] args) {
    SomeClass object = new SomeClass();
    // Note that Fory instances should be reused between
    // multiple serializations of different objects.
    Fory fory = Fory.builder()
      .withXlang(true)
      .requireClassRegistration(true)
      .build();
    // Registering types can reduce class name serialization overhead, but not mandatory.
    // If class registration enabled, all custom types must be registered.
    // Registration order must be consistent if id is not specified
    fory.register(SomeClass.class);
    byte[] bytes = fory.serialize(object);
    System.out.println(fory.deserialize(bytes));
  }
}

Multi-Thread Usage

import org.apache.fory.*;
import org.apache.fory.config.*;

public class Example {
  public static void main(String[] args) {
    SomeClass object = new SomeClass();
    ThreadSafeFory fory = Fory.builder()
      .withXlang(true)
      .buildThreadSafeFory();
    fory.register(SomeClass.class, 1);
    byte[] bytes = fory.serialize(object);
    System.out.println(fory.deserialize(bytes));
  }
}

Fory Instance Reuse Pattern

import org.apache.fory.*;
import org.apache.fory.config.*;

public class Example {
  private static final ThreadSafeFory fory = Fory.builder()
    .withXlang(true)
    .buildThreadSafeFory();

  static {
    fory.register(SomeClass.class, 1);
  }

  public static void main(String[] args) {
    SomeClass object = new SomeClass();
    byte[] bytes = fory.serialize(object);
    System.out.println(fory.deserialize(bytes));
  }
}

Xlang Mode And Native Mode

Use xlang mode for cross-language payloads and schemas shared with non-Java implementations. It is the default Java wire mode, and Java examples that use it set .withXlang(true) explicitly so the mode choice is visible.

Use native mode for Java-only traffic. Native mode is selected with .withXlang(false) and owns Java-specific object behavior such as JDK serialization hooks, Externalizable, dynamic object graphs, object copy, and Java native-mode zero-copy buffers. It is optimized for the JVM type system and supports a broader Java object surface than xlang mode. Compatible mode is enabled by default. Set .withCompatible(false) only when every reader and writer uses the same class schema and you want faster serialization and smaller size. If you are replacing JDK serialization, Kryo, FST, Hessian, or Java-only Protocol Buffers payloads, start with native mode.

See Native Serialization for Java-only serialization details and Xlang Serialization for Java xlang registration and interoperability rules.

Thread Safety

Fory provides two thread-safe Fory instance styles:

buildThreadSafeFory

This is the default choice. It uses a fixed-size shared ThreadPoolFory sized to 4 * availableProcessors() and is the preferred instance form for virtual-thread workloads:

ThreadSafeFory fory = Fory.builder()
  .withXlang(true)
  .withRefTracking(false)
  .withAsyncCompilation(true)
  .buildThreadSafeFory();

See more details in Virtual Threads.

ThreadLocalFory

Use buildThreadLocalFory() only when you explicitly want one Fory instance per long-lived platform thread, or when you want to pin that choice regardless of JDK version:

ThreadSafeFory fory = Fory.builder()
  .withXlang(true)
  .buildThreadLocalFory();
fory.register(SomeClass.class, 1);
byte[] bytes = fory.serialize(object);
System.out.println(fory.deserialize(bytes));

buildThreadSafeForyPool

Use buildThreadSafeForyPool(poolSize) when you want to set that fixed shared pool size explicitly. It eagerly creates poolSize Fory instances, keeps them in shared fixed slots, and then lets any caller borrow one through a thread-agnostic fast path. Calls only block when every pooled instance is already in use; the pool does not key cached instances by thread identity:

ThreadSafeFory fory = Fory.builder()
  .withXlang(true)
  .withRefTracking(false)
  .withAsyncCompilation(true)
  .buildThreadSafeForyPool(poolSize);

Builder Methods

// Single-thread Fory
Fory fory = Fory.builder()
  .withXlang(true)
  .withRefTracking(false)
  .withAsyncCompilation(true)
  .build();

// Thread-safe Fory (thread-safe Fory backed by a pool of Fory instances)
ThreadSafeFory fory = Fory.builder()
  .withXlang(true)
  .withRefTracking(false)
  .withAsyncCompilation(true)
  .buildThreadSafeFory();

// Explicit thread-local Fory instance
ThreadSafeFory threadLocalFory = Fory.builder()
  .withXlang(true)
  .buildThreadLocalFory();

Row Format

Fory row format is a separate cache-friendly binary format for random access, partial reads, and analytics workloads.

Features

  • Zero-Copy Random Access: Read fields and nested values without rebuilding complete objects.
  • Partial Reads: Decode only the data required by an analytics or query path.
  • Apache Arrow Integration: Convert between Fory row data and Arrow data for columnar processing.

Installation

Maven

<dependency>
  <groupId>org.apache.fory</groupId>
  <artifactId>fory-format</artifactId>
  <version>1.4.0</version>
</dependency>

Gradle

implementation("org.apache.fory:fory-format:1.4.0")

See Row Format for encoding, typed field access, partial deserialization, nested values, and Arrow integration.

Fory JSON

Fory JSON is a thread-safe JSON serialization framework for Java, extensively optimized for maximum performance across JSON encoding, decoding, and Java object mapping.

Features

  • Maximum Performance: Optimized readers and writers plus interpreted and runtime-generated codecs keep JSON encoding and decoding fast.
  • Java Object Mapping: Supports ordinary objects, Java 17 records, immutable creator-based classes, common JDK types, generic containers, custom codecs, and annotation-declared polymorphism.

Installation

fory-json includes fory-core transitively. Keep both modules on the same version when another dependency also brings fory-core into the application.

Maven

<dependency>
  <groupId>org.apache.fory</groupId>
  <artifactId>fory-json</artifactId>
  <version>1.4.0</version>
</dependency>

Gradle

implementation("org.apache.fory:fory-json:1.4.0")

On JDK 25 and later, use the same java.lang.invoke module open described in the binary serialization installation section.

Quick Start

ForyJson is immutable and thread-safe after construction. Reuse one instance across threads:

import org.apache.fory.json.ForyJson;

public final class JsonExample {
  private static final ForyJson JSON = ForyJson.builder().build();

  public static final class User {
    public long id;
    public String name;

    public User() {}

    public User(long id, String name) {
      this.id = id;
      this.name = name;
    }
  }

  public static void main(String[] args) {
    User input = new User(7, "Alice");

    String text = JSON.toJson(input);
    User fromText = JSON.fromJson(text, User.class);

    byte[] utf8 = JSON.toJsonBytes(input);
    User fromUtf8 = JSON.fromJson(utf8, User.class);

    System.out.println(fromText.name + " / " + fromUtf8.name);
  }
}

See JSON Support for supported types, annotations, custom codecs, security controls, and platform setup.

Platform Support

  • fory-core and fory-json support Java 8 and later; Java records require Java 17 or later.
  • fory-format targets Java 11 and later and is not supported on Android.
  • fory-core and fory-json run on standard JDKs, GraalVM native images, and Android API level 26 and later.

Next Steps