jackson

by FasterXML

FasterXML /jackson

Main Portal page for the Jackson project

5.9K Stars 1.0K Forks Last release: Not found 2.0K Commits 0 Releases

Available items

No Items, yet!

The developer of this repository has not created any items for sale yet. Need a bug fixed? Help with integration? A different license? Create a request here:

Jackson Project Home @github

This is the home page of the Jackson Project, formerly known as the standard JSON library for Java (or JVM platform in general), or, as the "best JSON parser for Java." Or simply as "JSON for Java." More than that, Jackson is a suite of data-processing tools for Java (and the JVM platform), including the flagship streaming JSON parser / generator library, matching data-binding library (POJOs to and from JSON) and additional data format modules to process data encoded in Avro, BSON, CBOR, CSV, Smile, (Java) Properties, Protobuf, XML or YAML; and even the large set of data format modules to support data types of widely used data types such as Guava, Joda, PCollections and many, many more (see below).

While the actual core components live under their own projects -- including the three core packages (streaming, databind, annotations); data format libraries; data type libraries; JAX-RS provider; and a miscellaneous set of other extension modules -- this project act as the central hub for linking all the pieces together.

A good companion to this README is the Jackson Project FAQ.

On reporting issues

First things first: unless you know what you are doing, DO NOT FILE ISSUES ON THE ISSUE TRACKER OF THIS REPO.

Instead, do one of the following:

  • For Jackson usage questions (for core components or modules), please use the Jackson-user Google group
  • For reporting issues on Jackson implementation, report it against one of the components
  • For suggestions and new ideas, try Jackson Future Ideas

Actively developed versions

Jackson suite has two major versions: 1.x is deprecated and no versions are released; 2.x is the actively developed version. These two major versions use different Java packages and Maven artifact ids, so they are not mutually compatible, but can peacefully co-exist: a project can depend on both Jackson 1.x and 2.x, without conflicts. This is by design and was chosen as the strategy to allow smoother migration from 1.x to 2.x.

The latest stable versions from these branches are:

  • 2.11.2, released on 02-Aug-2020
  • 1.9.13, released 14-Jul-2013

Recommended way to use Jackson is through Maven repositories; releases are made to Central Maven Repository (CMR). Individual projects' wiki pages sometimes also contain direct download links, pointing to CMR.

Release notes for 2.x releases are found from Jackson Releases page.

Active developed Jackson 2.x branches

Currently Jackson 2.x repositories have following actively developed branches:

  • 2.12
    : next minor version being developed (as of May 2020)
  • 2.11
    : current stable, actively maintained branch from which patch releases are still made
  • 2.10
    : previous stable branch, patch releases still made
  • 2.9
    : non-active branch from which micro-patch releases (like 2.9.10.5) MAY be made for individual components (
    jackson-databind
    usually)
  • master
    : next major version, 3.0. Still changing rapidly

Other

2.x
branches exist but no full releases are planned. Micro-patches still possible for critical security issues.

Active Jackson projects

Most projects listed below are lead by Jackson development team; but some by other at-large Jackson community members. We try to keep versioning of modules compatible to reduce confusion regarding which versions work together.

Core modules

Core modules are the foundation on which extensions (modules) build upon. There are 3 such modules currently (as of Jackson 2.x):

  • Streaming (docs) ("jackson-core") defines low-level streaming API, and includes JSON-specific implementations
  • Annotations (docs) ("jackson-annotations") contains standard Jackson annotations
  • Databind (docs) ("jackson-databind") implements data-binding (and object serialization) support on
    streaming
    package; it depends both on
    streaming
    and
    annotations
    packages

Third-party datatype modules

These extensions are plug-in Jackson

Module
s (registered with
ObjectMapper.registerModule()
), and add support for datatypes of various commonly used Java libraries, by adding serializers and deserializers so that Jackson
databind
package (
ObjectMapper
/
ObjectReader
/
ObjectWriter
) can read and write these types.

Datatype modules directly maintained by Jackson team are under the following Github repositories:

In addition, we are aware of additional modules that are not directly maintained by core Jackson team:

Providers for JAX-RS

Jackson JAX-RS Providers has handlers to add dataformat support for JAX-RS implementations (like Jersey, RESTeasy, CXF). Providers implement

MessageBodyReader
and
MessageBodyWriter
. Supported formats currently include
JSON
,
Smile
,
XML
,
YAML
and
CBOR
.

Data format modules

Data format modules offer support for data formats other than JSON. Most of them simply implement

streaming
API abstractions, so that databinding component can be used as is; some offer (and few require) additional
databind
level functionality for handling things like schemas.

Currently following data format modules are fully usable and supported (version number in parenthesis, if included, is the first Jackson 2.x version to include module; if missing, included from 2.0)

  • Avro: supports Avro data format, with
    streaming
    implementation plus additional
    databind
    -level support for Avro Schemas
  • CBOR: supports CBOR data format (a binary JSON variant).
  • CSV: supports Comma-separated values format --
    streaming
    api, with optional convenience
    databind
    additions
  • Ion (NEW with Jackson 2.9!): support for Amazon Ion binary data format (similar to CBOR, Smile, i.e. binary JSON - like)
  • (Java) Properties (2.8): creating nested structure out of implied notation (dotted by default, configurable), flattening similarly on serialization
  • Protobuf (2.6): supported similar to
    Avro
  • Smile: supports Smile (binary JSON) -- 100% API/logical model compatible via
    streaming
    API, no changes for
    databind
  • XML: supports XML; provides both
    streaming
    and
    databind
    implementations. Similar to JAXB' "code-first" mode (no support for "XML Schema first", but can use JAXB beans)
  • YAML: supports YAML, which being similar to JSON is fully supported with simple
    streaming
    implementation

There are also other data format modules, provided by developers outside Jackson core team:

  • BEncode: support for reading/writing BEncode (BitTorrent format) encoded data
  • bson4jackson: adds support for BSON data format (by Mongo project).
    • Implemented as full streaming implementation, which allows full access (streaming, data-binding, tree-model)
    • Also see [MongoJack] library below; while not a dataformat module, it allows access to BSON data as well.
  • EXIficient supports Efficient XML Interchange
  • jackson-dataformat-msgpack adds support MessagePack (aka
    MsgPack
    ) format
    • Implemented as full streaming implementation, which allows full access (streaming, data-binding, tree-model)
  • HOCON: experimental, partial implementation to support HOCON format -- work in progress
  • Rison: Jackson backend to support Rison)

JVM Language modules

  • Kotlin to handle native types of Kotlin
  • Scala to handle native Scala types (including but not limited to Scala collection/map types, case classes)
    • Currently (April 2020) Scala 2.10, 2.11, 2.12 and 2.13 are supported (2.9 was supported up to Jackson 2.3)

Support for Schemas

Jackson annotations define intended properties and expected handling for POJOs, and in addition to Jackson itself using this for reading/writing JSON and other formats, it also allows generation of external schemas. Some of this functionality is included in above-mentioned data-format extensions; but there are also many stand-alone Schema tools, such as:

JSON Schema

Other schema languages

Other modules, stable

Other fully usable modules by FasterXML team include:

  • Base modules:
    • Afterburner: speed up databinding by 30-40% with bytecode generation to replace use of Reflection for field access, method/constructor calls
    • Guice: extension that allows injection values from Guice injectors (and basic Guice annotations), instead of standard
      @JacksonInject
      (or in addition to)
    • JAXB Annotations: allow use of
      JAXB
      annotations as an alternative (in addition to or instead of) standard Jackson annotations
    • Mr Bean: "type materialization" -- let Mr Bean generate implementation classes on-the-fly (NO source code generation), to avoid monkey code
    • OSGi: allows injection of values from OSGi registry, via standard Jackson
      @JacksonInject
      annotation
    • Paranamer: tiny extension for automatically figuring out creator (constructor, factory method) parameter names, to avoid having to specify
      @JsonProperty
      .

Jackson jr

While Jackson databind is a good choice for general-purpose data-binding, its footprint and startup overhead may be problematic in some domains, such as mobile phones; and especially for light usage (couple of reads or writes). In addition, some developers find full Jackson API overwhelming.

For all these reasons, we decided to create a much simpler, smaller library, which supports a subset of functionality, called Jackson jr. It builds on Jackson Streaming API, but does not depend on databind. As a result its size (both jar, and runtime memory usage) is considerably smaller; and its API is very compact.

Third-party non-module libraries based on Jackson

Jackson helper libraries

  • Jackson Ant path filter adds powerful filtering of properties to serialize, using Ant Path notation for hierarchic filtering

Support for datatypes

Other things related to or inspired by Jackson

  • Pyckson is a Python library that aims for same goals as Java Jackson, such as Convention over Configuration
  • Rackson is a Ruby library that offers Jackson-like functionality on Ruby platform

Support

Community support

Jackson components are supported by the Jackson community through mailing lists, Gitter forum, Github issues. See Contributing for full details.

Enterprise support

In addition to free (for all) community support, enterprise support—starting with version 2.10—is available as part of the Tidelift Subscription for (most) Jackson components.

The maintainers of

Jackson
and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. Learn more.

Reporting security vulnerabilities

The recommended mechanism for reporting possible security vulnerabilities follows so-called "Coordinated Disclosure Plan" (see definition of DCP for general idea). The first step is to file a Tidelift security contact: Tidelift will route all reports via their system to maintainers of relevant package(s), and start the process that will evaluate concern and issue possible fixes, send update notices and so on. Note that you do not need to be a Tidelift subscriber to file a security contact.

Alternatively you may also report possible vulnerabilities to

info
at fasterxml dot com mailing address. Note that filing an issue to go with report is fine, but if you do that please DO NOT include details of security problem in the issue but only in email contact. This is important to give us time to provide a patch, if necessary, for the problem.

Documentation

Web sites

Tutorials

For first-time users there are many good Jackson usage tutorials, including:

Note on reporting Bugs

Jackson bugs need to be reported against component they affect: for this reason, issue tracker is not enabled for this project. If you are unsure which specific project issue affects, the most likely component is

jackson-databind
, so you would use Jackson Databind Issue Tracker.

Java JSON library comparisons

Since you probably want opinions by Java developers NOT related to Jackson project, regarding which library to use, here are links to some of existing independent comparisons:

We use cookies. If you continue to browse the site, you agree to the use of cookies. For more information on our use of cookies please see our Privacy Policy.