解决Feign反序列化LocalDateTime异常

默认情况下，feign使用org.springframework.cloud.openfeign.support.SpringDecoder，默认使用的jackson反序列化对象，不做任何处理的话，会报序列化异常问题。部分异常信息如下：

nested exception is >org.springframework.http.converter.HttpMessageNotReadableException:
JSON parse error: Cannot deserialize value of type `java.time.LocalDateTime` from >String 
"2020-11-04 14:43:37": Failed to deserialize java.time.LocalDateTime: 
(java.time.format.DateTimeParseException)

我们可以将Decoder替换成Gson,通过配置java8时间类的序列化规则使其支持反序列化java8时间类对象

1. 引入Feign的Gson支持

        <dependency>
            <groupId>io.github.openfeign</groupId>
            <artifactId>feign-gson</artifactId>
        </dependency>

2. 配置Encoder，Decoder序列化类，指定为Gson

@Configuration
public class FeignCodecConfiguration {

    private static final String DEFAULT_DATE_TIME_FORMATTER = "yyyy-MM-dd HH:mm:ss";

    private static final String DEFAULT_DATE_FORMATTER = "yyyy-MM-dd";

    private static final String DEFAULT_TIME_FORMATTER = "HH:mm:ss";

    private static final Gson gson = GSON = new GsonBuilder()
                .serializeNulls()
                .registerTypeAdapter(LocalDateTime.class, (JsonSerializer<LocalDateTime>) (localDateTime, typeOfSrc, context) -> {
                    if (Objects.isNull(localDateTime)) {
                        return new JsonPrimitive("");
                    }
                    return new JsonPrimitive(localDateTime.format(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMATTER)));
                })
                .registerTypeAdapter(LocalDateTime.class, (JsonDeserializer<LocalDateTime>) (json1, typeOfT, context) -> {
                    String string = json1.getAsJsonPrimitive().getAsString();
                    if (Strings.isNullOrEmpty(string)) {
                        return null;
                    }
                    return LocalDateTime.parse(string, DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMATTER));
                })
                .registerTypeAdapter(LocalDate.class, (JsonSerializer<LocalDate>) (localDate, type, jsonSerializationContext) -> {
                    if (Objects.isNull(localDate)) {
                        return new JsonPrimitive("");
                    }
                    return new JsonPrimitive(localDate.format(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMATTER)));
                })
                .registerTypeAdapter(LocalDate.class, (JsonDeserializer<LocalDate>) (json, typeOfT, context) -> {
                    String string = json.getAsJsonPrimitive().getAsString();
                    if (Strings.isNullOrEmpty(string)) {
                        return null;
                    }
                    return LocalDate.parse(string, DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMATTER));
                })
                .registerTypeAdapter(LocalTime.class, (JsonSerializer<LocalTime>) (localTime, type, jsonSerializationContext) -> {
                    if (Objects.isNull(localTime)) {
                        return new JsonPrimitive("");
                    }
                    return new JsonPrimitive(localTime.format(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMATTER)));
                })
                .registerTypeAdapter(LocalTime.class, (JsonDeserializer<LocalTime>) (json, typeOfT, context) -> {
                    String string = json.getAsJsonPrimitive().getAsString();
                    if (Strings.isNullOrEmpty(string)) {
                        return null;
                    }
                    return LocalTime.parse(string, DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMATTER));
                })
                .create();
        PRETTY_GSON = new GsonBuilder()
                .serializeNulls()
                .registerTypeAdapter(LocalDateTime.class, (JsonSerializer<LocalDateTime>) (localDateTime, typeOfSrc, context) -> {
                    if (Objects.isNull(localDateTime)) {
                        return new JsonPrimitive("");
                    }
                    return new JsonPrimitive(localDateTime.format(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMATTER)));
                })
                .registerTypeAdapter(LocalDateTime.class, (JsonDeserializer<LocalDateTime>) (json1, typeOfT, context) -> {
                    String string = json1.getAsJsonPrimitive().getAsString();
                    if (Strings.isNullOrEmpty(string)) {
                        return null;
                    }
                    return LocalDateTime.parse(string, DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMATTER));
                })
                .registerTypeAdapter(LocalDate.class, (JsonSerializer<LocalDate>) (localDate, type, jsonSerializationContext) -> {
                    if (Objects.isNull(localDate)) {
                        return new JsonPrimitive("");
                    }
                    return new JsonPrimitive(localDate.format(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMATTER)));
                })
                .registerTypeAdapter(LocalDate.class, (JsonDeserializer<LocalDate>) (json, typeOfT, context) -> {
                    String string = json.getAsJsonPrimitive().getAsString();
                    if (Strings.isNullOrEmpty(string)) {
                        return null;
                    }
                    return LocalDate.parse(string, DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMATTER));
                })
                .registerTypeAdapter(LocalTime.class, (JsonSerializer<LocalTime>) (localTime, type, jsonSerializationContext) -> {
                    if (Objects.isNull(localTime)) {
                        return new JsonPrimitive("");
                    }
                    return new JsonPrimitive(localTime.format(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMATTER)));
                })
                .registerTypeAdapter(LocalTime.class, (JsonDeserializer<LocalTime>) (json, typeOfT, context) -> {
                    String string = json.getAsJsonPrimitive().getAsString();
                    if (Strings.isNullOrEmpty(string)) {
                        return null;
                    }
                    return LocalTime.parse(string, DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMATTER));
                })
                .setPrettyPrinting()
                .create();

    @Bean
    public GsonDecoder gsonDecoder() {
        return new GsonDecoder(gson);
    }

    @Bean
    public GsonEncoder gsonEncoder() {
        return new GsonEncoder(gson);
    }
}