如何为java.time.LocalDateTime自定义全局杰克逊反序列化器

Question

杰克逊的serialize/deserializejava.time在全球范围内都很好，但它的默认日期时间格式是ISO标准，比如2018-01-10T10:20:30 for LocalDateTime和2018-01-10T10:20:30+08:00 for OffsetDateTime。但是我需要为LocalDateTime和OffsetDateTime设置一个全局本地格式，比如LocalDateTime和OffsetDateTime，而不需要T和OffsetTime (使用本地默认OffsetTime)。我该怎么做？

注:我知道@JsonFormat，@JsonSerialize和@JsonDeserialize。这不是全球性的环境。

Answer 1

弹簧靴

    @SpringBootApplication
    public class Application implements Jackson2ObjectMapperBuilderCustomizer {
        public static void main(String[] args) {
            SpringApplication.run(Application.class, args);
        }

        @Override
        public void customize(Jackson2ObjectMapperBuilder builder) {
            DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
            LocalDateTimeSerializer localDateTimeSerializer = new LocalDateTimeSerializer(formatter);

            builder.failOnEmptyBeans(false) // prevent InvalidDefinitionException Error
                    .serializerByType(LocalDateTime.class, localDateTimeSerializer);
        }
    }

Springboot & Spring框架

    @Configuration
    public class WebMvcConfig implements WebMvcConfigurer {
        @Override
        public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
            DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
            LocalDateTimeSerializer localDateTimeSerializer = new LocalDateTimeSerializer(formatter);
            LocalDateTimeDeserializer localDateTimeDeserializer = new LocalDateTimeDeserializer(formatter);

            JavaTimeModule module = new JavaTimeModule();
            module.addSerializer(LocalDateTime.class, localDateTimeSerializer);
            module.addDeserializer(LocalDateTime.class, localDateTimeDeserializer);

            ObjectMapper mapper = new ObjectMapper();
            mapper.registerModule(module);
            // add converter at the very front
            // if there are same type mappers in converters, setting in first mapper is used.
            converters.add(0, new MappingJackson2HttpMessageConverter(mapper));
        }
    }

希望这能帮到你。

Answer 2

您可以配置一个ObjectMapper。本页解释了https://www.baeldung.com/jackson-serialize-dates是如何实现的。我想你想要接近那一页的例子4的东西。

然后，您需要使之成为全局ObjectMapper。不同的框架使用不同的方法。本页解释了如何在Spring和Spring Configuring ObjectMapper in Spring中这样做。对于其他人，只要谷歌就可以了。

Answer 3

如果您正在全局地使用ObjectMapper的单个实例(并且想要一个独立于Spring/Java8Jackson模块的解决方案)，您可以这样做：

public ObjectMapper getCustomConfigMapper() {
    final ObjectMapper mapper = new ObjectMapper();
    final SimpleModule module = new SimpleModule();
    module.addDeserializer(LocalDateTime.class, new CustomLocaDateTimeDeserializer());
    mapper.registerModule(module);
    return mapper;
}

public static class CustomLocaDateTimeDeserializer extends JsonDeserializer<LocalDateTime> {

    public static final DateTimeFormatter CUSTOM_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

    @Override
    public LocalDateTime deserialize(JsonParser jsonParser, DeserializationContext __) throws IOException {
        final String value = jsonParser.getText().strip();
        return LocalDateTime.parse(value, CUSTOM_FORMATTER);
    }
}