FilteringJacksonJsonProvider.java 文件源码

@Override
public void writeTo(
    Object o, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType,
    MultivaluedMap<String, Object> httpHeaders, OutputStream os) throws IOException {
  String fields = uriInfo.getQueryParameters() == null ? null
      : uriInfo.getQueryParameters().getFirst("fields");

  FieldFilter fieldFilter = FieldFilter.create(fields);
  if (!fieldFilter.hasFilters()) {
    super.writeTo(o, type, genericType, annotations, mediaType, httpHeaders, os);
    return;
  }

  JsonGenerator jgen = objectMapper.getFactory().createGenerator(os);
  TokenBuffer tokenBuffer = new TokenBuffer(objectMapper, false);
  objectMapper.writeValue(tokenBuffer, o);
  JsonParser jsonParser = tokenBuffer.asParser();
  fieldFilter.writeJson(jsonParser, jgen);
  jgen.flush();
}