Jackson: How to add custom property to the JSON without modifying the POJO

Question

I am developing a REST interface for my app using Jackson to serialize my POJO domain objects to JSON representation. I want to customize the serialization for some types to

Answer 1

Inspired from what wajda said and written in this gist:

Here is how to add a listener for bean serialization in jackson 1.9.12. In this example, the listerner is considered as a Chain Of Command which interface is :

public interface BeanSerializerListener {
    void postSerialization(Object value, JsonGenerator jgen) throws IOException;
}

MyBeanSerializer.java:

public class MyBeanSerializer extends BeanSerializerBase {
    private final BeanSerializerListener serializerListener;

    protected MyBeanSerializer(final BeanSerializerBase src, final BeanSerializerListener serializerListener) {
        super(src);
        this.serializerListener = serializerListener;
    }

    @Override
    public void serialize(final Object bean, final JsonGenerator jgen, final SerializerProvider provider) throws IOException, JsonGenerationException {
        jgen.writeStartObject();
        if (_propertyFilterId != null) {
            serializeFieldsFiltered(bean, jgen, provider);
        } else {
            serializeFields(bean, jgen, provider);
        }

        serializerListener.postSerialization(bean, jgen);

        jgen.writeEndObject();
    }
}

MyBeanSerializerBuilder.java:

public class MyBeanSerializerBuilder extends BeanSerializerBuilder {
    private final BeanSerializerListener serializerListener;

    public MyBeanSerializerBuilder(final BasicBeanDescription beanDesc, final BeanSerializerListener serializerListener) {
        super(beanDesc);
        this.serializerListener = serializerListener;
    }

    @Override
    public JsonSerializer build() {
        BeanSerializerBase src = (BeanSerializerBase) super.build();
        return new MyBeanSerializer(src, serializerListener);
    }
}

MyBeanSerializerFactory.java:

public class MyBeanSerializerFactory extends BeanSerializerFactory {

    private final BeanSerializerListener serializerListener;

    public MyBeanSerializerFactory(final BeanSerializerListener serializerListener) {
        super(null);
        this.serializerListener = serializerListener;
    }

    @Override
    protected BeanSerializerBuilder constructBeanSerializerBuilder(final BasicBeanDescription beanDesc) {
        return new MyBeanSerializerBuilder(beanDesc, serializerListener);
    }
}

The last class below shows how to provide it using Resteasy 3.0.7:

@Provider
public class ObjectMapperProvider implements ContextResolver {
    private final MapperConfigurator mapperCfg;

    public ObjectMapperProvider() {
        mapperCfg = new MapperConfigurator(null, null);
        mapperCfg.setAnnotationsToUse(new Annotations[]{Annotations.JACKSON, Annotations.JAXB});
        mapperCfg.getConfiguredMapper().setSerializerFactory(serializerFactory);
    }

    @Override
    public ObjectMapper getContext(final Class type) {
        return mapperCfg.getConfiguredMapper();
    }
}