Develop Reference

Using Jackson annotations in java-library (not application)

I am writing a java-library that will be included included as a dependency in other projects. I want some of the library's classes to de/serializable with Jackson's ObjectMapper. Out of habit, I have used annotations to tell Jackson how to de/serialize my classes.
Will the annotations' functionality get exported by the library (like api)?
Will a dependent application be able to use the an ObjectMapper created by the default constructor? Is any further configuration necessary?
Can I put the annotations into a custom Jackson Module for dependent applications to register with their ObjectMapper?
I have been very surprised to find a dearth of documentation for this use case.

Serialize POJO to JSON through a provider

What is a common way to serialize Java Beans to JSON in a automatic fashion? The #Produces(MediaType.APPLICATION_JSON) doesnt seem to handle the conversion under the hood. Do we create our own JSON Providers or is there another way? Currently im trying to handle it via the ContextResolver:
https://docs.oracle.com/javaee/7/api/javax/ws/rs/ext/ContextResolver.html
It is my understanding that the #Produces annotation should help create the expected output if a java object is returned from one of the resource class methods.

You do not have to code the jackson based provider yourself.
In apache karaf you can simply install the feature aries-jax-rs-whiteboard-jackson.
If you are not using karaf you can install the bundles from the feature yourself:
https://github.com/apache/aries-jax-rs-whiteboard/blob/master/jax-rs.features/src/main/feature/feature.xml

Serialization of Java 8 ZonedDateTime with Jackson and JavaTimeModule

I'm trying to use Jackson to serialize and deserialize objects (marshall/unmarshall) from and to JSON. Some of these objects have Java 8 LocalDate and ZonedDateTime. I've read here that the best option is to use jackson-datatype-jsr310
serialize/deserialize java 8 java.time with Jackson JSON mapper
However, when I try to use this:
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JavaTimeModule());
I get this error:
java.lang.IllegalAccessError: tried to access method com.fasterxml.jackson.databind.ser.std.StdSerializer.<init>(Ljava/lang/Class;)V from class com.fasterxml.jackson.datatype.jsr310.JavaTimeModule
Any clue? I'm using Jackson 2.6.0, jackson-datatype-jsr310 2.6.0 and am deploying to Tomcat 8.
Thanks and best regards

In the end, the problem was I had a different version of Jackson, due to a dependency with Jongo. jackson-datatype-jsr310 2.6.0 needs Jackson 2.6.0 and Jackson 2.4.1 was being deployed.

jackson 2.4 looking for old class when deserialising

i am developing a restful service with tomcat 7 and jdk 1.6. for json handling i am using jackson 2.4.2 and it works fine except when i try and deserialise an object (that it has no trouble serialising).
the error is:
java.lang.ClassNotFoundException: org.codehaus.jackson.JsonFactory
which is the place where jackson 1.x kept that particular class. my jackson 2.4.2 has it at
com.fasterxml.jackson.core.JsonFactory
i have no idea as to why it is trying to link the old class. i never used jackson 1.x.
what i use:
asm-3.3.1
commons-io-2.4
jackson-core-2.4.2
jackson-databind-2.4.2
jersey-bundle-1.18
mysql-connector-java-5.1.27
and
com.fasterxml.jackson.annotation
which i have taken from github. what library could be trying to import the old jackson module? any help would be much appreciated.

The issue certainly comes from trying to use Jackson 1.x ObjectMapper and missing underlying JsonFactory for 1.x. Since these come from difference jars (jackson-mapper-asl vs jackson-core-asl), it is likely that somehow one is missing.
Now, since you are not directly using Jackson 1.x, question is who is: perhaps jersey is relying on 1.x?
So there are two related questions: (a) if Jackson 1.x is needed, to bring in core jar as well, or (b) how to remove use of Jackson 1.x altogether.
Note that technically it is quite possible to use both 1.x and 2.x versions of Jackson, since 2.x was specifically designed to be able to co-exist. This to make upgrades easier, and allow gradual (component-by-component) upgrading.

Specify lower Jackson version in Spring 3.1.2

This is the opposite of what most Spring users are clamoring to do, but I was wondering if its possible to specify that Jackson 1.9.7 be used by Spring (3.1.2) and NOT Jackson 2+.
The project I'm working on relies on other projects that use Jackson 2, so it get pulls in as a transitive dependency. From there Spring picks it up to handle JSON serialization. This in turn borks my application because of custom annotations I've created that require the Jackson version be 1.9.7.

Not sure if this helps, but note that you can also add both Jackson 1 and Jackson 2 annotations in value classes. I have done this at work, to help transition from Jackson 1.9 to Jackson 2.x. And in fact different parts of code use different version: unit test helper methods were migrated first, and later on production code, section by section.
As with library version, use of two sets of annotations is not optimal, but doing so may help reduce risk of version upgrade.
Finally, it is also possible to use an AnnotationIntrospector that can use both sets of annotations (I don't have a link at hand, but I know a Jackson user published version he created); usually Jackson 2 JacksonAnnotationIntrospector that also recognizes Jackson 1 annotations. This avoids duplication of annotations and makes it possible to upgrade code first, then convert annotations.