Jackson xml and json root element

Question

I have a service which returns objects in JSON and XML format.

http://localhost:8091/apiN/xml/2

XML Result

Answer 1

The JSON and XML structures are not equivalent. In XML you want a list of RestObject and in JSON you want a list whose elements wrap instances of RestObject in another object. This isn't something you can get with a simple Jackson annotation, you would need a custom serializer only for JSON serialization. First of all, getting the desired XML format is straightforward:

class RestObject implements Serializable {
    private LocalDateTime timestamp;
    private String title;
    private String fullText;
    private Long id;
    private Double value;
}

@JsonRootName("restObjectList")
class RestObjectList {
    @JacksonXmlProperty(localName = "restObject")
    @JacksonXmlElementWrapper(useWrapping = false)
    private List restObjectList;
}

If you absolutely want to wrap each element in the array in json you'll need a custom serializer e.g.

class RestObjectSerializer extends JsonSerializer {
    @Override
    public void serialize(RestObject value, JsonGenerator gen, SerializerProvider serializers) throws
            IOException {
        gen.writeStartObject();
        gen.writeObjectFieldStart("restObject");
        gen.writeObjectField("timeStamp", value.getTimestamp());
        gen.writeStringField("title", value.getTitle());
        // other fields
        gen.writeEndObject();
        gen.writeEndObject();
    }
}

And register only with the ObjectMapper that serializes JSON so it doesn't interfere with serialization to XML:

ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule("MyModule");
module.addSerializer(RestObject.class, new RestObjectSerializer());
mapper.registerModule(module);