Play 2.1 JSON API没有为Type提供序列化器Map[String, Ojbect]。
为特定类型定义case class和Format，而不是Map[String, Object]：
// { "val1" : "xxx", "val2" : ["a", "b", "c"] }
case class Hoge(val1: String, val2: List[String])
implicit val hogeFormat = Json.format[Hoge]
如果您不想创建案例类。以下代码为Map [String，Object]提供JSON序列化器/反序列化器：
implicit val objectMapformat = new Format[Map[String, Object]] {
def writes(map: Map[String, Object]): JsValue =
Json.obj(
"val1" -> map("val1").asInstanceOf[String],
"val2" -> map("val2").asInstanceOf[List[String]]
)
def reads(jv: JsValue): JsResult[Map[String, Object]] =
JsSuccess(Map("val1" -> (jv \ "val1").as[String], "val2" -> (jv \ "val2").as[List[String]]))
}
import play.api.libs.json._
import play.api.libs.json.Reads._
import play.api.libs.json.Json.JsValueWrapper
implicit val objectMapformat = new Format[Map[String, Object]] {
def writes(map: Map[String, Object]): JsValue =
Json.obj(map.map{case (s, o) =>
val ret:(String, JsValueWrapper) = o match {
case _:String => s -> JsString(o.asInstanceOf[String])
case _ => s -> JsArray(o.asInstanceOf[List[String]].map(JsString(_)))
}
ret
}.toSeq:_*)
def reads(jv: JsValue): JsResult[Map[String, Object]] =
JsSuccess(jv.as[Map[String, JsValue]].map{case (k, v) =>
k -> (v match {
case s:JsString => s.as[String]
case l => l.as[List[String]]
})
})
}
样例代码：
val jv = Json.toJson(Map("val1" -> "xxx", "val2" -> List("a", "b", "c"), "val3" -> "sss", "val4" -> List("d", "e", "f")))
println(jv)
val jr = Json.fromJson[Map[String, Object]](jv)
println(jr.get)
输出：
> {"val1":"xxx","val2":["a","b","c"],"val3":"sss","val4":["d","e","f"]}
> Map(val1 -> xxx, val2 -> List(a, b, c), val3 -> sss, val4 -> List(d, e, f))
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