Spring:在不修改域类的情况下格式化REST响应中的日期

Question

我有一个Spring 5（不是Spring Boot）项目，它有一个endpoint返回在依赖关系jar中定义的对象（我不能修改它）。这个对象有一个日期字段（LocalDateTime）。

日期在响应中的格式如下：

{
    "dayOfMonth": 21,
    "dayOfWeek": "THURSDAY",
    "month": "FEBRUARY",
    "year": 2019,
    "dayOfYear": 52,
    "hour": 11,
    "minute": 24,
    "nano": 753000000,
    "second": 32,
    "monthValue": 2,
    "chronology": {
        "id": "ISO",
        "calendarType": "iso8601"
    }
}

我怎么能把is写成ISO 8601或类似的呢？我尝试添加以下依赖项:

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
    <version>2.9.8</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jdk8</artifactId>
    <version>2.9.8</version>
</dependency>

我还尝试为ObjectMapper创建一个主bean:

@Bean
@Primary
public ObjectMapper objectMapper() {
    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.registerModule(new JavaTimeModule());
    objectMapper.registerModule(new Jdk8Module());
    objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
    return objectMapper;
}

映射器在显式使用时工作正常，但在Spring返回JSON REST响应时则不然。

为了简化而不是写完整的代码，我希望像下面这样的endpoint能够正确地隐式格式化日期。

    @GetMapping(path = "/date", produces = "application/json")
    public @ResponseBody ResponseEntity<LocalDateTime> date(@RequestHeader HttpHeaders headers) {
        return new ResponseEntity<>(LocalDateTime.now(), HttpStatus.OK);
    }

谢谢。

Answer 1

我通过添加一个配置类来修复它，该类将我的ObjectMapper链接到基于此博客条目的HTTPMessageConverter。

@Configuration
public class JacksonConfiguration {

    @Autowired
    ObjectMapper mapper;

    private RequestMappingHandlerAdapter annotationMethodHandlerAdapter;

    @PostConstruct
    public void init() {
        List<HttpMessageConverter<?>> messageConverters = annotationMethodHandlerAdapter.getMessageConverters();
        for (HttpMessageConverter<?> messageConverter : messageConverters) {
            if (messageConverter instanceof MappingJackson2HttpMessageConverter) {
                MappingJackson2HttpMessageConverter m = (MappingJackson2HttpMessageConverter) messageConverter;
                m.setObjectMapper(mapper);
            }
        }
    }

    @Autowired
    public void setAnnotationMethodHandlerAdapter(RequestMappingHandlerAdapter annotationMethodHandlerAdapter) {
        this.annotationMethodHandlerAdapter  = annotationMethodHandlerAdapter;
    }
}