Scala json4s密封特性作为枚举
我们的状态定义为:Scala json4s密封特性作为枚举,scala,enums,traits,json4s,sealed,Scala,Enums,Traits,Json4s,Sealed,我们的状态定义为: sealed trait Status case object Status { case object StatusA extends Status case object StatusB extends Status case object StatusC extends Status } 我们的状况如下: val status = Status.StatusA 有没有办法用预定义的json4sfomratters(反)序列化这种结构 我们尝试使用defu
sealed trait Status
case object Status {
case object StatusA extends Status
case object StatusB extends Status
case object StatusC extends Status
}
我们的状况如下:
val status = Status.StatusA
有没有办法用预定义的json4s
fomratters(反)序列化这种结构
我们尝试使用defult formatter,如:
implicit val formats = new org.json4s.DefaultFormats
但它没有起作用。接下来,我们尝试使用json4s
提供的ext
和Enum支持:
implicit val formats = org.json4s.DefaultFormats + new org.json4s.ext.EnumSerializer(Status)
但它没有再次起作用。我们必须将
密封特征
的结构完全改变为实际的枚举
s。有没有办法用case class
es来实现这一点?这是一个完整的工作示例,我对您的类做了一些更改,以使示例更简单,这样您就可以以不同的方式使用“name”,您实际上可以省略“def name”,但在这种情况下,您需要稍微更改serialiser。第二个序列化程序就在下面
sealed trait Status {
def name: String
}
case object Status {
def apply(name: String): Status = name match {
case StatusA.name => StatusA
case StatusB.name => StatusB
case StatusC.name => StatusC
case _ => throw new UnsupportedOperationException("Unknown value")
}
}
case object StatusA extends Status {
override val name = "StatusA"
}
case object StatusB extends Status {
override val name = "StatusB"
}
case object StatusC extends Status {
override val name = "StatusC"
}
class StatusSerializer extends CustomSerializer[Status](formats =>
( {
case JString(s) => Status(s)
case JNull => throw new UnsupportedOperationException("No status specified")
}, {
case status: Status => JString(status.name)
})
)
case class SimpleRichObject(someString: String, someInt: Int, statuses: List[Status])
object Test extends App {
implicit val formats = DefaultFormats + new StatusSerializer
val obj = SimpleRichObject("Answer to life the universe and everything", 42, List(StatusA, StatusB, StatusC))
def toCompactJsonString(any: Any) = {
JsonMethods.compact(JsonMethods.render(Extraction.decompose(any)))
}
def toPrettyJsonString(any: Any) = {
JsonMethods.pretty(JsonMethods.render(Extraction.decompose(any)))
}
/** To Json */
println(s"Compact json:\n${toCompactJsonString(obj)}")
println(s"Pretty json:\n${toPrettyJsonString(obj)}")
/** From Json */
val json =
"""{
| "someString":"Here is a another String",
| "someInt":1234,
| "statuses":["StatusA","StatusB"]
|}""".stripMargin
val richObj = JsonMethods.parse(json).extract[SimpleRichObject]
println(s"Rich object toString: $richObj")
}
这是第二个序列化程序,通过使用第二个序列化程序,您不需要在“枚举”中定义额外的代码
这是一个运行时的外观,压缩json:
{"someString":"Answer to life the universe and everything","someInt":42,"statuses":["StatusA","StatusB","StatusC"]}
漂亮的json:
{
"someString":"Answer to life the universe and everything",
"someInt":42,
"statuses":["StatusA","StatusB","StatusC"]
}
富对象toString:SimpleRichObject(这里是另一个字符串,1234,列表(StatusA,StatusB))
{
"someString":"Answer to life the universe and everything",
"someInt":42,
"statuses":["StatusA","StatusB","StatusC"]
}