scala - 将 JDouble 转换为 Double(JSON 库)

Question

我正在使用 https://github.com/json4s/json4s .如何将其值(如 JDouble、JBool)转换为相应的 Scala 数据类型——Double 和 Boolean？

更新:

scala> (json \ "status")
res8: org.json4s.JValue = JBool(false)

scala> (json \ "status").extract[Boolean]
<console>:16: error: No org.json4s.Formats found. Try to bring an instance of org.json4s.Formats in scope or use the org.json4s.DefaultFormats.
              (json \ "status").extract[Boolean]

Answer 1

如 Read Me 中所述，继承人如何做到这一点.. :)

  import org.json4s._
  import org.json4s.native.JsonMethods._

  implicit val formats = DefaultFormats 

  val json = parse("""
            {
                "mydouble" : 3.14,
                "isPie" : true
             }
    """) 

  val dbl = (json \ "mydouble").extractOpt[Double]
  //> dbl  : Option[Double] = Some(3.14)
  val bool = (json \ "isPie").extractOpt[Boolean] 
  //> bool  : Option[Boolean] = Some(true)