LocalDateTime将无效日期解析为有效日期，并且不引发任何异常

Question

我在Spring API的请求体中使用LocalDateTime。

  @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-mm-dd HH:mm:ss")
  @DateTimeFormat(pattern = "yyyy-MM-dd HH:mm:ss")
  @JsonDeserialize(using = LocalDateTimeDeserializer.class)
  @JsonSerialize(using = LocalDateTimeSerializer.class)
  private LocalDateTime createdAt;

当我在请求中输入无效日期时，例如“2020-02-31 00:00:00”，它会自动转换为“2020-02-29 00:00:00”。我想在无效日期的情况下抛出异常。官方留档中提到它会转换为以前的有效日期。

 In some cases, changing the specified field can cause the resulting date-time to become invalid,
 such as changing the month from 31st January to February would make the day-of-month invalid.
 In cases like this, the field is responsible for resolving the date.
 Typically it will choose the previous valid date, 
 which would be the last valid day of February in this example.

Answer 1

您需要为此编写一个自定义的序列化程序。

class CustomLocalDateTimeSerializer extends StdSerializer<LocalDateTime> {
    private static final DateTimeFormatter FORMATTER
            = DateTimeFormatter.ofPattern("yyyy-mm-dd HH:mm:ss");

    ...

    @Override
    public void serialize(LocalDateTime value, JsonGenerator generator, SerializerProvider provider)
            throws IOException, JsonProcessingException {
        // Do your validation using FORMATTER.
        // Serialize the value using generator and provider.
    }
}

然后，您可以在注释中使用它。

@JsonSerialize(using = CustomLocalDateTimeSerializer.class)

请注意，DateTimeFormatter在格式化/解析无效值时引发异常。

查看LocalDateTimeSerializer的源代码以了解必须执行的操作。查看Jackson Date-10。序列化Java8 Date而无需任何额外依赖，以获取编写自定义序列化程序的示例。这类似于自定义反序列化程序。