scala：json4s庫—Json與對象轉換

github: https://github.com/json4s/json4s

使用 json4s庫

依賴：

val json4sNative = "org.json4s" %% "json4s-native" % "3.2.11"

數據類型：

sealed abstract class JValue

case object JNothing extends JValue // 'zero' for JValue
case object JNull extends JValue
case class JString(s: String) extends JValue
case class JDouble(num: Double) extends JValue
case class JDecimal(num: BigDecimal) extends JValue
case class JInt(num: BigInt) extends JValue
case class JLong(num: Long) extends JValue
case class JBool(value: Boolean) extends JValue
case class JObject(obj: List[JField]) extends JValue
case class JArray(arr: List[JValue]) extends JValue

type JField = (String, JValue)

demo：

import org.json4s.JsonDSL._
import org.json4s.jackson.JsonMethods._
import org.json4s._
object Json4sTest {
    def main(args: Array[String]): Unit = {
        implicit val format = DefaultFormats
        val str = """{"table":"spark_test.user","op_type":"I","op_ts":"2018-05-21 15:29:35.655148","after":{"ID":111, "name":"張三"}}"""
        val jValue: JValue = parse(str)
        println(jValue)
        // JObject(List((table,JString(spark_test.user)), (op_type,JString(I)), (op_ts,JString(2018-05-21 15:29:35.655148)), (after,JObject(List((ID,JInt(111)), (name,JString(張三)))))))

        val res2 = (jValue \ "after")
        println(res2)
        //JObject(List((ID,JInt(111)), (name,JString(張三))))

        val res3 = res2.values
        println(res3)
        //Map(ID -> 111, name -> 張三)

        val r = ("name" -> "abc") ~ ("class" -> 123) ~
            ("timestamp" -> System.currentTimeMillis()) ~
            ("age" -> Seq(1, 2, 3))
        println(compact(render(r)))
        //{"name":"abc","class":123,"timestamp":1527573731901,"age":[1,2,3]}
        println(pretty(render(r)))
        /* { "name" : "abc", "class" : 123, "timestamp" : 1527573731901, "age" : [ 1, 2, 3 ] } */
    }
}