问Scala 2.10:动态实例化案例类

EN

def fillInner(cls: Class[_]) : Any = {
  val declaredConstructors = cls.getDeclaredConstructors
  if (declaredConstructors.length != 1)
  Logger.error(/*T.toString + */" has " + declaredConstructors.length + " constructors --- only 1 currently supported.")
  val constructor = declaredConstructors.headOption.get

  val m = constructor.getParameterTypes.map(p => {
      Logger.info("getName " + p.getName +" --- getCanonicalName " + p.getCanonicalName)
      Logger.info(p.getCanonicalName)

    p.getCanonicalName match {
      case "java.lang.String" => /*"Name"->*/ val s : java.lang.String = "DEFAULT STRING"
        s
      case "long" => /*"Name"-> */ val l : java.lang.Long = new java.lang.Long(99)
        l
      case "int" => /*"Name"->*/ val i : java.lang.Integer = new java.lang.Integer(99)
        i
      case _ => fillInner(p)
    }
  })

def fill[T: ClassTag]: T = fillInner(classOf[T].runtimeClass).asInstanceOf[T]

trait Supplier[T] {
  def supply: T
}
object Supplier[T] {
  implicit val intSupplier = new Supplier[Int] {
    def supply = 99
  }
  implicit val stringSupplier = ...
  implicit val emptyHListSupplier = new Supplier[HNil] {
    def supply = HNil
  }
  implicit def consHListSupplier[H, T <: HList](
    implicit headSupplier: Supplier[H], 
      tailSupplier: Supplier[T]) = new Supplier[H :: T] {
    def supply = headSupplier.supply :: tailSupplier.supply
   }
}

import scala.reflect.api
import scala.reflect.api.{TypeCreator, Universe}
import scala.reflect.runtime.universe._

object Maker {
  val mirror = runtimeMirror(getClass.getClassLoader)

  var makerRunNumber = 1

  def apply[T: TypeTag]: T = {
    val method = typeOf[T].companion.decl(TermName("apply")).asMethod
    val params = method.paramLists.head
    val args = params.map { param =>
      makerRunNumber += 1
      param.info match {
        case t if t <:< typeOf[Enumeration#Value] => chooseEnumValue(convert(t).asInstanceOf[TypeTag[_ <: Enumeration]])
        case t if t =:= typeOf[Int] => makerRunNumber
        case t if t =:= typeOf[Long] => makerRunNumber
        case t if t =:= typeOf[Date] => new Date(Time.now.inMillis)
        case t if t <:< typeOf[Option[_]] => None
        case t if t =:= typeOf[String] && param.name.decodedName.toString.toLowerCase.contains("email") => s"random-$arbitrary@give.asia"
        case t if t =:= typeOf[String] => s"arbitrary-$makerRunNumber"
        case t if t =:= typeOf[Boolean] => false
        case t if t <:< typeOf[Seq[_]] => List.empty
        case t if t <:< typeOf[Map[_, _]] => Map.empty
        // Add more special cases here.
        case t if isCaseClass(t) => apply(convert(t))
        case t => throw new Exception(s"Maker doesn't support generating $t")
      }
    }

    val obj = mirror.reflectModule(typeOf[T].typeSymbol.companion.asModule).instance
    mirror.reflect(obj).reflectMethod(method)(args:_*).asInstanceOf[T]
  }

  def chooseEnumValue[E <: Enumeration: TypeTag]: E#Value = {
    val parentType = typeOf[E].asInstanceOf[TypeRef].pre
    val valuesMethod = parentType.baseType(typeOf[Enumeration].typeSymbol).decl(TermName("values")).asMethod
    val obj = mirror.reflectModule(parentType.termSymbol.asModule).instance

    mirror.reflect(obj).reflectMethod(valuesMethod)().asInstanceOf[E#ValueSet].head
  }

  def convert(tpe: Type): TypeTag[_] = {
    TypeTag.apply(
      runtimeMirror(getClass.getClassLoader),
      new TypeCreator {
        override def apply[U <: Universe with Singleton](m: api.Mirror[U]) = {
          tpe.asInstanceOf[U # Type]
        }
      }
    )
  }

  def isCaseClass(t: Type) = {
    t.companion.decls.exists(_.name.decodedName.toString == "apply") &&
      t.decls.exists(_.name.decodedName.toString == "copy")
  }
}

val user = Maker[User]
val user2 = Maker[User].copy(email = "someemail@email.com")