无法从 String 反序列化 LocalDateTime 类型的值答案

【问题标题】：Cannot deserialize value of type LocalDateTime from String无法从 String 反序列化 LocalDateTime 类型的值
【发布时间】：2020-10-23 17:36:35
【问题描述】：

我有以下DTO 和Entity：

public class PaymentDto {

    private String provider;

    private Duration timeDifferenceDate;

    public PaymentDto() {
        // Empty for framework
    }

    public PaymentDto(Payment payment) {
        this.provider = payment.getProvider();
        this.setRegistrationDate(payment.getRegistrationDate());
    }

    public Duration getRegistrationDate() {
        return timeDifferenceDate;
    }

    public void setRegistrationDate(LocalDateTime registrationDate) {
        LocalDateTime now = LocalDateTime.now();
        Duration duration = Duration.between(now, registrationDate);
        this.timeDifferenceDate = duration;
    }

}

public class Payment {

    private LocalDateTime registrationDate;

    public Payment() {
        // Empty for framework
    }

但是当它从Payment 转换为PaymentDto 时，我遇到了JSON 解码问题，特别是从LocalDateTime 转换为Duration。有什么想法吗？

    @Override
    public List<PaymentDto> readAll() {
        return this.paymentPersistence.readAll().stream()
                .map(PaymentDto::new).collect(Collectors.toList());
    }

org.springframework.core.codec.DecodingException: JSON decoding error: Cannot deserialize value of type `java.time.LocalDateTime` from String "PT-1.015005S": Failed to deserialize java.time.LocalDateTime: (java.time.format.DateTimeParseException) Text 'PT-1.015005S' could not be parsed at index 0; nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize value of type `java.time.LocalDateTime` from String "PT-1.015005S": Failed to deserialize java.time.LocalDateTime: (java.time.format.DateTimeParseException) Text 'PT-1.015005S' could not be parsed at index 0
 at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: com.user.rest.dtos.PaymentDto["registrationDate"])

    at org.springframework.http.codec.json.AbstractJackson2Decoder.processException(AbstractJackson2Decoder.java:215)
    Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
    |_ checkpoint ⇢ Body from GET http://localhost:61072/payments [DefaultClientResponse]
Stack trace:
        at org.springframework.http.codec.json.AbstractJackson2Decoder.processException(AbstractJackson2Decoder.java:215)

顺便谢谢你。 ;)

【问题讨论】：

标签： java json serialization duration localdatetime

【解决方案1】：

LocalDateTime 不能转换为Duration，反之亦然。除了Serializable（当然还有Object），它们的层次结构中没有什么共同点。

替换

private LocalDateTime registrationDate;

与

private Duration registrationDate;

或者创建一个类型为Duration的新实例变量。

【讨论】：

【解决方案2】：

作为@Arvind Kumar Avinash mentioned above，您需要在设置器PaymentDto::setRegistrationDate 中提供适当的类型Duration。

如果您从返回LocalDateTime 字段的实体填充DTO，您还应该修改“转换”构造函数。此外，在计算持续时间时，您应该将registrationDate 放在首位，以避免“负”持续时间（较早的时刻优先）。

public PaymentDto(Payment payment) {
    this.provider = payment.getProvider();
    this.setRegistrationDate(Duration.between(
        payment.getRegistrationDate(),  // older "start" date should go first
        LocalDateTime.now()
    ));
}

public void setRegistrationDate(Duration timeDifference) 
    this.timeDifferenceDate = timeDifference;
}

【讨论】：