com.fasterxml.jackson.databind.ObjectMapper#treeAsTokens ( )源码实例Demo

@Test
void deserialize() throws IOException {
    final ObjectMapper objectMapper = new ObjectMapper();

    final InstantDeserializer deserializer = new InstantDeserializer();
    final JsonParser parser = objectMapper.treeAsTokens(objectMapper.readTree("\"2016-08-11T11:28:34.085Z\""));
    parser.nextToken();
    final Instant instant = deserializer.deserialize(parser, objectMapper.getDeserializationContext());

    assertEquals(Instant.from(
        ZonedDateTime.of(
            LocalDate.of(2016, 8, 11),
            LocalTime.of(11, 28, 34, (int) TimeUnit.MILLISECONDS.toNanos(85)),
            ZoneOffset.UTC
        )
    ), instant);
}
 

private BiFunction<JsonNode, Type, Object> makeDeserialiser(ObjectMapper mapper) {
    final TypeFactory typeFactory = mapper.getTypeFactory();
    return (node, type) -> {
        JavaType javaType = typeFactory.constructType(type);
        try {
            final JsonParser jsonParser = mapper.treeAsTokens(node);
            final ObjectCodec codec = jsonParser.getCodec();

            return codec.readValue(jsonParser, javaType);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    };
}
 

private BiFunction<JsonNode, Type, Object> makeDeserialiser(ObjectMapper mapper) {
    final TypeFactory typeFactory = mapper.getTypeFactory();
    return (node, type) -> {
        JavaType javaType = typeFactory.constructType(type);
        try {
            final JsonParser jsonParser = mapper.treeAsTokens(node);
            final ObjectCodec codec = jsonParser.getCodec();

            return codec.readValue(jsonParser, javaType);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    };
}
 

@SuppressWarnings("unchecked")
public static <T extends MessageOrBuilder> List<T> writeAndReadBack(ObjectMapper mapper, List<T> values) {
  if (values.isEmpty()) {
    return Collections.emptyList();
  }

  Class<T> messageType = (Class<T>) values.get(0).getClass();
  JsonParser parser = mapper.treeAsTokens(toTree(mapper, values));

  try {
    return Lists.newArrayList(mapper.readValues(parser, messageType));
  } catch (IOException e) {
    throw new RuntimeException(e);
  }
}