Kotlin & Jackson：为数据类字段指定自定义序列化时出现类型错误

Question

我有一个Kotlin数据类，它在Spring Boot项目中串行化为JSON。我想自定义序列化为JSON时日期的格式。字段的名称应使用默认规则序列化。这表达了我想做的事情：

class ZonedDateTimeSerialiser : JsonSerializer<ZonedDateTime>() {
@Throws(IOException::class)
fun serialize(value: ZonedDateTime, gen: JsonGenerator, serializers: SerializerProvider?) {
val parseDate: String? = value.withZoneSameInstant(ZoneId.of("Europe/Warsaw"))
.withZoneSameLocal(ZoneOffset.UTC)
.format(DateTimeFormatter.ISO_DATE_TIME)
gen.writeString(parseDate)
}
}
data class OrderNotesRequest(
@JsonSerialize(using = ZonedDateTimeSerialiser::class)
val date: ZonedDateTime = ZonedDateTime.now()
)

但我得到了一个类型错误：

Type mismatch.
Required:
KClass<out (JsonSerializer<Any!>..JsonSerializer<*>?)>
Found:
KClass<ZonedDateTimeSerialiser>

我确实尝试将参数从annotation切换到contentUsing，但类型错误保持不变。

Answer 1

以下内容适用于我的

object JacksonRun {
@JvmStatic
fun main(args: Array<String>) {
val objMapper = ObjectMapper().apply {
registerModule(KotlinModule())
}
val order = OrderNotesRequest()
println(objMapper.writeValueAsString(order))
}
}
data class OrderNotesRequest(
@JsonSerialize(using = ZonedDateTimeSerialiser::class)
val date: ZonedDateTime = ZonedDateTime.now()
)
class ZonedDateTimeSerialiser : JsonSerializer<ZonedDateTime>() {
@Throws(IOException::class)
override fun serialize(value: ZonedDateTime, gen: JsonGenerator, serializers: SerializerProvider?) {
val parseDate: String = value.withZoneSameInstant(ZoneId.of("Europe/Warsaw"))
.withZoneSameLocal(ZoneOffset.UTC)
.format(DateTimeFormatter.ISO_DATE_TIME)
gen.writeString(parseDate)
}
}

build.gradle.kts:

dependencies {
implementation("com.fasterxml.jackson.core:jackson-core:2.13.2")
implementation("com.fasterxml.jackson.core:jackson-annotations:2.13.2")
implementation("com.fasterxml.jackson.core:jackson-databind:2.13.2")
implementation("com.fasterxml.jackson.module:jackson-module-kotlin:2.13.0")
}

给我输出：

{"date":"2022-03-21T10:29:19.381498Z"}

请确保您有正确的JsonSerializer导入

import com.fasterxml.jackson.databind.JsonSerializer

并将CCD_ 3标记添加到CCD_