Maven jackson

Maven jackson DEFAULT

Recently while working with Jackson within a Spring Boot project, I encountered an issue I’d like to share with you.

Jackson is currently the leading option for parsing JSON in Java. The Jackson library is composed of three components: Jackson Databind, Core, and Annotation. Jackson Databind has internal dependencies on Jackson Core and Annotation. Therefore, adding Jackson Databind to your Maven POM dependency list will include the other dependencies as well. To use the latest Jackson library, you need to add the following dependency in the Maven POM.

. . . <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.7.4</version> </dependency> . . .

The above dependency works well in other Java projects, but unfortunately in a Spring Boot 1.3.x application, you may stumble upon this error.

Jackson Dependency Conflict Error in Spring Boot

You may see several different errors. Here are some additional examples.

java.lang.NoSuchMethodError: com.fasterxml.jackson.annotation.JsonFormat$Value.empty()Lcom/fasterxml/jackson/annotation/JsonFormat$Value; at com.fasterxml.jackson.databind.cfg.MapperConfig.<clinit>(MapperConfig.java:50) at com.fasterxml.jackson.databind.ObjectMapper.<init>(ObjectMapper.java:543) at com.fasterxml.jackson.databind.ObjectMapper.<init>(ObjectMapper.java:460) at guru.springframework.blog.jsonwithjackson.jsonreader.JsonNodeDemo.<init>(JsonNodeDemo.java:19) at guru.springframework.blog.jsonwithjackson.jsonreader.JsonNodeDemoTest.testReadJsonWithJsonNode(JsonNodeDemoTest.java:15) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runners.Suite.runChild(Suite.java:128) at org.junit.runners.Suite.runChild(Suite.java:27) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:119) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42) at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) java.lang.NoClassDefFoundError: Could not initialize class com.fasterxml.jackson.databind.SerializationConfig at com.fasterxml.jackson.databind.ObjectMapper.<init>(ObjectMapper.java:543) at com.fasterxml.jackson.databind.ObjectMapper.<init>(ObjectMapper.java:460) at guru.springframework.blog.jsonwithjackson.jsonreader.ObjectMapperDemo.readJsonWithObjectMapper(ObjectMapperDemo.java:13) at guru.springframework.blog.jsonwithjackson.jsonreader.ObjectMapperDemoTest.testReadJson(ObjectMapperDemoTest.java:13) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runners.Suite.runChild(Suite.java:128) at org.junit.runners.Suite.runChild(Suite.java:27) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:119) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42) at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) java.lang.NoClassDefFoundError: Could not initialize class com.fasterxml.jackson.databind.SerializationConfig at com.fasterxml.jackson.databind.ObjectMapper.<init>(ObjectMapper.java:543) at com.fasterxml.jackson.databind.ObjectMapper.<init>(ObjectMapper.java:460) at guru.springframework.blog.jsonwithjackson.jsonreader.ObjectMapperToMapDemo.readJsonWithObjectMapper(ObjectMapperToMapDemo.java:15) at guru.springframework.blog.jsonwithjackson.jsonreader.ObjectMapperToMapDemoTest.testReadJsonWithObjectMapper(ObjectMapperToMapDemoTest.java:12) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runners.Suite.runChild(Suite.java:128) at org.junit.runners.Suite.runChild(Suite.java:27) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:119) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42) at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234) at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

This error occurs due to Jackson dependency conflict. We are working on a Spring Boot project and it’s inheriting from the Spring Boot parent POM that includes Jackson. Without any Jackson dependency in the project POM, let’s print the Maven dependency tree to view the in-built Jackson dependencies.

mvn dependency:tree -Dincludes=com.fasterxml.jackson.core

The output is this.

[INFO] – ---------------------------------------------------------------------- [INFO] Building Blog Posts 0.0.1-SNAPSHOT [INFO] – ---------------------------------------------------------------------- [INFO] [INFO] - – maven-dependency-plugin:2.10:tree (default-cli) @ blogposts – - [INFO] guru.springframework:blogposts:jar:0.0.1-SNAPSHOT [INFO] \- com.fasterxml.jackson.core:jackson-databind:jar:2.6.5:compile [INFO] +- com.fasterxml.jackson.core:jackson-annotations:jar:2.6.5:compile [INFO] \- com.fasterxml.jackson.core:jackson-core:jar:2.6.5:compile [INFO] – ---------------------------------------------------------------------- [INFO] BUILD SUCCESS [INFO] – ---------------------------------------------------------------------- [INFO] Total time: 2.053 s [INFO] Finished at: 2016-05-18T07:32:59-04:00 [INFO] Final Memory: 19M/309M [INFO] – ----------------------------------------------------------------------
Spring Framework 5

As you can see above, the Spring Boot parent POM uses an older version of Jackson (2.6.5).

Now, if we add the Jackson dependency to our Maven POM using the version like this:

. . . <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.7.4</version> </dependency> . . .

Maven will pulling in older versions of Jackson-annotation and Jackson-core and overriding the newer ones. We can see this by running the command again.

[INFO] – ---------------------------------------------------------------------- [INFO] Building Blog Posts 0.0.1-SNAPSHOT [INFO] – ---------------------------------------------------------------------- [INFO] [INFO] - – maven-dependency-plugin:2.10:tree (default-cli) @ blogposts – - [INFO] guru.springframework:blogposts:jar:0.0.1-SNAPSHOT [INFO] \- com.fasterxml.jackson.core:jackson-databind:jar:2.7.4:compile [INFO] +- com.fasterxml.jackson.core:jackson-annotations:jar:2.6.5:compile [INFO] \- com.fasterxml.jackson.core:jackson-core:jar:2.6.5:compile [INFO] – ---------------------------------------------------------------------- [INFO] BUILD SUCCESS [INFO] – ---------------------------------------------------------------------- [INFO] Total time: 1.977 s [INFO] Finished at: 2016-05-18T07:35:09-04:00 [INFO] Final Memory: 19M/309M [INFO] – ----------------------------------------------------------------------

I did not expect Maven to behave this way in dependency resolution. The POM for the primary Jackson artifact does call for the proper version. However, this seems to be getting overridden by the versions specified explicitly in the Spring Boot parent POM.

Ideally, when working with Spring Boot, is to leverage the curated dependencies in the Spring Boot parent POM. In this case, we drop the version for the Jackson dependency so it will get inherited from the Spring Boot Parent POM.

. . . <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> </dependency> . . .

Now, the version will be inherited from the parent POM, and the issue will be resolved.

But what if we want to use a newer version of Jackson? The proper way is to exclude the inherent dependencies, and explicitly add their new versions, like this.

. . . <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.7.4</version> <exclusions> <exclusion> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> </exclusion> <exclusion> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.7.4</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.7.4</version> </dependency> . . .

This POM configuration will override the Jackson dependencies set in the Spring Boot parent POM.

This post is specific to Spring Boot version 1.3.3. Naturally, the Spring Boot team will be evolving the version of Jackson used in future releases.

For developers accustomed to working with Maven dependencies, it’s a very easy mistake to include the version in the dependency declaration. This can cause some unintended issues due to version conflicts. It is a little bit of a paradigm shift for experienced developers to depend on the Spring Boot parent POM. Some won’t want to relinquish control, but in the long run I expect you will be better of leveraging the Spring Boot curated dependencies.

If you’d like to learn more about Jackson and Spring Boot checkout my other posts:

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Sours: https://springframework.guru/jackson-dependency-issue-spring-boot-maven/

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

Maven

Functionality of this package is contained in Java package .

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 ).

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 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.


General

Usage typically starts with creation of a reusable (and thread-safe, once configured) 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.xJsonFactory factory =newJsonFactory(); // configure, if necessary: factory.enable(JsonReadFeature.ALLOW_JAVA_COMMENTS);

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

JsonFactory factory = objectMapper.getFactory();

Usage, simple reading

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

An example can be found from Reading and Writing Event Streams

Usage, simple writing

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

An example can be found from Reading and Writing Event Streams


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 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.


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 (instead of )

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
Sours: https://github.com/FasterXML/jackson-core
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Jackson Installation

The Java JSON API called Jackson consists of one core JAR file (project) and two other JAR files that use the core JAR file. The three JAR files (projects) in the Jackson JSON API are:

  • Jackson Core
  • Jackson Annotations
  • Jackson Databind

These projects use each other in that sequence too. Jackson Annotation uses the Jackson Core features, and the Jackson Databind uses Jackson Annotation.

Jackson also has a few extra projects for parsing other data formats than JSON. For instance, to read and write CBOR you can add the artifact to your classpath too.

In order to "install" Jackson in your Java application you need to add these JAR files to the classpath of your application. There are several ways to do so. I will cover two here.

Adding the JAR Files to Your Classpath

In order to use any of the Jackson projects (JAR files) you must add the corresponding JAR file to the classpath of your application. You can do so in several different ways.

Before you even start adding the Jackson JAR files to your classpath, you need to decide what version of the Jackson JSON API to use. To do so, go to the Jackson website and see what versions are available. If you are not already using a specific version of Jackson in your project, use the latest stable version. Write the version number down. You may need it later.

You can find a list of Jackson releases here:

https://github.com/FasterXML/jackson-core/releases

Jackson Maven Dependencies

If your project uses Maven to build (and resolve + download dependencies), you need to add Jackson as a dependency to your project's POM file. Here is how Jackson as Maven dependencies look:

<dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.9.6</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.9.6</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.9.6</version> </dependency>

Note, that both and have "transitive dependencies" to (and to ). This means, that if you plan to use the project, you just need to include that as dependency in your Maven POM file. Then it will transitively include the other two projects as dependencies. Regardless, I like to add my dependencies explicitly so I can see what I am using (but that's just me).

In order to read and write CBOR encoded data with Jackson you will also need to add the Jackson CBOR Maven dependency:

<dependency> <groupId>com.fasterxml.jackson.dataformat</groupId> <artifactId>jackson-dataformat-cbor</artifactId> <version>2.9.6</version> </dependency>

In order to read and write MessagePack encoded data with Jackson you will also need to add the Jackson MessagePack Maven dependency:

<dependency> <groupId>org.msgpack</groupId> <artifactId>jackson-dataformat-msgpack</artifactId> <version>0.8.16</version> </dependency>

In order to read and write YAML encoded data with Jackson you will also need to add the Jackson YAML Maven dependency:

<dependency> <groupId>com.fasterxml.jackson.dataformat</groupId> <artifactId>jackson-dataformat-yaml</artifactId> <version>2.9.0</version> </dependency>

Adding the JAR Files Directly to the Classpath

Another option is to add the Jackson JAR files directly to the classpath of your application. To do so you must first download the JAR files. You can download the finished JAR files via the central Maven repository. Go to:

http://search.maven.org

Search for the project you want to use (e.g. , or ). Once you find the right project, make sure you click the "all versions" link next to the version number in the search result. That will show you a list of the previous versions of that project. Click around until you find a link directly to the JAR file for that project and that version. Then download the JAR file.

Once the JAR files are downloaded, add them to the classpath of your project. You can do so within your IDE, and / or within the scripts (bash or cmd) you use to run your application.

Next: Jackson ObjectMapper

Sours: http://tutorials.jenkov.com/java-json/jackson-installation.html
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