Is there a way to use Java 8 lambda style to add custom Jackson serializer?

Question

Right now adding Jackson custom serializer via Jackson module is verbose and does not lend itself to the new Java 8 lambda pattern.

Is there a way to use Java 8 lambda style to add custom Jackson serializer?

Answer 1

You can make a simple Jackson8Module that would allow you to do the following:

ObjectMapper jacksonMapper = new ObjectMapper();
Jackson8Module module = new Jackson8Module();
module.addStringSerializer(LocalDate.class, (val) -> val.toString());
module.addStringSerializer(LocalDateTime.class, (val) -> val.toString());
jacksonMapper.registerModule(module);

The Jackson8Module code just extends Jackson SimpleModule to provide Java 8 friendly methods (it can be extended to support other Jackson Module methods) :

public class Jackson8Module extends SimpleModule {

    public <T> void addCustomSerializer(Class<T> cls, SerializeFunction<T> serializeFunction){
        JsonSerializer<T> jsonSerializer = new JsonSerializer<T>() {
            @Override
            public void serialize(T t, JsonGenerator jgen, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {
                serializeFunction.serialize(t, jgen);
            }
        };
        addSerializer(cls,jsonSerializer);
    }

    public <T> void addStringSerializer(Class<T> cls, Function<T,String> serializeFunction) {
        JsonSerializer<T> jsonSerializer = new JsonSerializer<T>() {
            @Override
            public void serialize(T t, JsonGenerator jgen, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {
                String val = serializeFunction.apply(t);
                jgen.writeString(val);
            }
        };
        addSerializer(cls,jsonSerializer);
    }

    public static interface SerializeFunction<T> {
        public void serialize(T t, JsonGenerator jgen) throws IOException, JsonProcessingException;
    }
}

Here is the gist of the Jackson8Module: https://gist.github.com/jeremychone/a7e06b8baffef88a8816