dierent / jackson-core

Core part of Jackson that defines Streaming API as well as basic shared abstractions

Overview

This project contains core low-level incremental ("streaming") parser and generator abstractions used by Jackson Data Processor. It also includes the default implementation of handler types (parser, generator) that handle JSON format. The core abstractions are not JSON specific, although naming does contain 'JSON' in many places, due to historical reasons. Only packages that specifically contain word 'json' are JSON-specific.

This package is the base on which Jackson data-binding package builds on. It is licensed under Apache License 2.0.

Alternate data format implementations (like Smile (binary JSON), XML, CSV, Protobuf, and CBOR) also build on this base package, implementing the core interfaces, making it possible to use standard data-binding package regardless of underlying data format.

Project contains versions 2.0 and above: source code for earlier (1.x) versions can be found from Jackson-1 github repo.

Status

Type	Status
Build (CI)
Artifact
OSS Sponsorship
Javadocs
Code coverage (2.15)
CodeQ (ClusterFuzz)

Get it!

Maven

Functionality of this package is contained in Java package com.fasterxml.jackson.core.

To use the package, you need to use following Maven dependency:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>${jackson.version.core}</version>
</dependency>

or download jars from Maven repository or links on Wiki. Core jar is a functional OSGi bundle, with proper import/export declarations.

Package has no external dependencies, except for testing (which uses JUnit).

Non-Maven

For non-Maven use cases, you download jars from Central Maven repository.

Core jar is also a functional OSGi bundle, with proper import/export declarations, so it can be use on OSGi container as is.

Jackson 2.10 and above include module-info.class definitions so the jar is also a proper Java module (JPMS).

Jackson 2.12 and above include additional Gradle 6 Module Metadata for version alignment with Gradle.

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Use it!

General

Usage typically starts with creation of a reusable (and thread-safe, once configured) JsonFactory instance:

// Builder-style since 2.10:
JsonFactory factory = JsonFactory.builder()
// configure, if necessary:
     .enable(JsonReadFeature.ALLOW_JAVA_COMMENTS)
     .build();

// older 2.x mechanism, still supported for 2.x
JsonFactory factory = new JsonFactory();
// configure, if necessary:
factory.enable(JsonReadFeature.ALLOW_JAVA_COMMENTS);

Alternatively, you have an ObjectMapper (from Jackson Databind package) handy; if so, you can do:

JsonFactory factory = objectMapper.getFactory();

Usage, simple reading

All reading is by using JsonParser (or its sub-classes, in case of data formats other than JSON), instance of which is constructed by JsonFactory.

An example can be found from Reading and Writing Event Streams

Usage, simple writing

All writing is by using JsonGenerator (or its sub-classes, in case of data formats other than JSON), instance of which is constructed by JsonFactory:

An example can be found from Reading and Writing Event Streams

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Compatibility

JDK

Jackson-core package baseline JDK requirement:

• Versions 2.0 - 2.13 require JDK 6
• Versions 2.14 and above require JDK 8

Android

List is incomplete due to recent addition of compatibility checker.

• 2.13: Android SDK 19+
• 2.14 and above: Android SDK 26+

for information on Android SDK versions to Android Release names see Android version history

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Release Process

Starting with Jackson 2.15, releases of this module will be SLSA compliant: see issue #844 for details.

Release process is triggered by

./release.sh

script which uses Maven Release plug-in under the hood (earlier release plug-in was directly invoked).

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Support

Community support

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

Enterprise support

Available as part of the Tidelift Subscription.

The maintainers of jackson-core 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.

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Further reading

Differences from Jackson 1.x

Project contains versions 2.0 and above: source code for the latest 1.x version (1.9.13) is available from FasterXML/jackson-1 repo (unmaintained).

Note that the main differences compared to 1.0 core jar are:

• Maven build instead of Ant
• Annotations carved out to a separate package (that this package depends on)
• Java package is now com.fasterxml.jackson.core (instead of org.codehaus.jackson)

Links

• Project Wiki has JavaDocs and links to downloadable artifacts
• Jackson (portal) has links to all FasterXML-maintained "official" Jackson components
• Jackson Docs is the portal/hub for all kinds of Jackson documentation