Customizing ObjectMapper in a JAX-RS application

If you use Jackson as the JSON provider in your JAX-RS application, you may want to redefine the default Jackson behaviour or even fine-tune the serializarion and deserialization processes.

It can be achieved with a ContextResolver for ObjectMapper:

@Provider
public class ObjectMapperContextResolver implements ContextResolver<ObjectMapper> {

    private final ObjectMapper mapper;

    public ObjectMapperContextResolver() {
        this.mapper = createObjectMapper();
    }

    @Override
    public ObjectMapper getContext(Class<?> type) {
        return mapper;
    }

    private ObjectMapper createObjectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
        return mapper;
    }
}

Under the hood, the ObjectMapper instance created above will be picked by the JacksonJsonProvider class, the Jackson implementation for MessageBodyReader and MessageBodyWriter that binds JSON content to and from Java objects in JAX-RS.

If, for some reason, you need to access the ObjectMapper directly, use the @Context annotation to inject Providers in your JAX-RS resource or provider classes:

@Context
private Providers providers;

Then look up the ContextResolver to get the ObjectMapper instance:

ContextResolver<ObjectMapper> resolver = 
        providers.getContextResolver(ObjectMapper.class, MediaType.WILDCARD_TYPE);
ObjectMapper mapper = resolver.getContext(ObjectMapper.class);

I usually use the following serialization and deserialization settings:

mapper.enable(SerializationFeature.INDENT_OUTPUT);
mapper.enable(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT);
mapper.disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);
mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);

For applications with Java 8 or above, I also register the following modules:

mapper.registerModule(new Jdk8Module());
mapper.registerModule(new JavaTimeModule());
mapper.registerModule(new ParameterNamesModule());

Don’t forget to add the following dependencies to your project:

<dependency>
    <groupId>com.fasterxml.jackson.module</groupId>
    <artifactId>jackson-module-parameter-names</artifactId>
    <version>${jackson.version}</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jdk8</artifactId>
    <version>${jackson.version}</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
    <version>${jackson.version}</version>
</dependency>