Jackson @ConstructorProperties

IMPORTANT: Since jackson-databind 2.9, this feature works out of the box and this add-on is no longer needed (see com.fasterxml.jackson.databind.MapperFeature.INFER_CREATOR_FROM_CONSTRUCTOR_PROPERTIES).

This repository contains support for the @java.beans.ConstructorProperties annotation for Jackson version 2 and up to 2.8.

This feature is useful when you want Jackson te deserialize immutable objects. Names of constructor arguments are not retained in Java class files and therefore must be supplied using external methods, most often annotations. In Jackson, each argument of the constructor must be annotated using a @JsonProperty proprietary annotation. This is quite verbose and moreover needlessly couples the value class to Jackson.

Since Java SE 6, the standard libraries provide an annotation just for this purpose - the @java.beans.ConstructorProperties. Unlike the @JsonProperty annotations, this one is put on the constructor itself, reducing clutter in the method signature. This library adds support for the ConstructorProperties annotation to Jackson, allowing simplification of value classes and their de-coupling from Jackson.

Usage

Registering the library in Jackson:

        ObjectMapper objectMapper = new ObjectMapper()
                .setAnnotationIntrospector(new ConstructorPropertiesAnnotationIntrospector());
        objectMapper.readValue(json, TestObject.class);

Example

Instead of writing

public class TestObject {
    public TestObject(@JsonProperty("arg1") int arg1, @JsonProperty("arg2") String arg2) {
        ...
    }
}

You can now use

public class TestObject {
    @ConstructorProperties("arg1", "arg2")
    public TestObject(int arg1, String arg2) {
        ...
    }
}