Feign request return value inverse sequence localdatetime exception record

Preface

Used by recent project team feign Call remote service , The consumer reported the following exception

feign-localDateTime abnormal .png

From the abnormal information, we can get localdatime Deserialized exception , And this anomaly is because jackson Failure to process results in . So we can do it for jackson Of ObjectMapper Fit it

resolvent

1、 stay pom.xml introduce

    <dependency>
                <groupId>com.fasterxml.jackson.datatype</groupId>
                <artifactId>jackson-datatype-jsr310</artifactId>
                <version>${jackson.version}</version>
            </dependency>

            <dependency>
                <groupId>com.fasterxml.jackson.datatype</groupId>
                <artifactId>jackson-datatype-jdk8</artifactId>
                <version>${jackson.version}</version>
            </dependency>

notes ： jackson-datatype-jsr310 This is used to support jsr310 Standard time ,jackson-datatype-jdk8 Used to support new specific JDK8 The type of , for example Optional

2、 Replace the default ObjectMapper

@Configuration
public class LocalDateTimeConfig  {

    public static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";


  
    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.registerModule(new Jdk8Module());
        objectMapper.setDateFormat(new SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT));
        objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        objectMapper.disable(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE);
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));
        objectMapper.registerModule(javaTimeModule).registerModule(new ParameterNamesModule());
        return objectMapper;
    }

Questions ： Why replace the default ObjectMapper after ,feign You can deal with LocalDateTime

The answer lies in

@Configuration(proxyBeanMethods = false)
public class FeignClientsConfiguration {

	@Autowired
	private ObjectFactory<HttpMessageConverters> messageConverters;


	@Bean
	@ConditionalOnMissingBean
	public Decoder feignDecoder() {
		return new OptionalDecoder(
				new ResponseEntityDecoder(new SpringDecoder(this.messageConverters)));
	}
}

and messageConverters The default converter is based on HttpMessageConvertersAutoConfiguration And come

@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(HttpMessageConverter.class)
@Conditional(NotReactiveWebApplicationCondition.class)
@AutoConfigureAfter({ GsonAutoConfiguration.class, JacksonAutoConfiguration.class, JsonbAutoConfiguration.class })
@Import({ JacksonHttpMessageConvertersConfiguration.class, GsonHttpMessageConvertersConfiguration.class,
		JsonbHttpMessageConvertersConfiguration.class })
public class HttpMessageConvertersAutoConfiguration {

	static final String PREFERRED_MAPPER_PROPERTY = "spring.http.converters.preferred-json-mapper";

	@Bean
	@ConditionalOnMissingBean
	public HttpMessageConverters messageConverters(ObjectProvider<HttpMessageConverter<?>> converters) {
		return new HttpMessageConverters(converters.orderedStream().collect(Collectors.toList()));
	}

ObjectProvider It has the function of delayed loading , It will be loaded according to the actual situation .springboot Of web The module will introduce... By default Jackson Related packages . There is a passage on the official website

Insert picture description here

This indicates the default HttpMessageConverter by MappingJackson2HttpMessageConverter, and MappingJackson2HttpMessageConverter Make use of objectMapper To serialize and deserialize

The above words are sorted in code as follows

 public static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";


    @Bean
    public Decoder feignDecoder() {
        return new ResponseEntityDecoder(new SpringDecoder(messageConverters()));
    }

    public ObjectFactory<HttpMessageConverters> messageConverters() {
        return () -> new HttpMessageConverters(mappingJackson2HttpMessageConverter());
    }

    public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
        return new MappingJackson2HttpMessageConverter(objectMapper());
    }

    public ObjectMapper objectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.registerModule(new Jdk8Module());
        objectMapper.setDateFormat(new SimpleDateFormat(DEFAULT_DATE_TIME_FORMAT));
        objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        objectMapper.disable(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE);
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));
        javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)));
        objectMapper.registerModule(javaTimeModule).registerModule(new ParameterNamesModule());
        return objectMapper;
    }

summary

Exception information is important , Source code is very important , The official website is equally important