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java - 如何在scala中动态键入cast Any？

问题描述

我想将“任何”对象转换为运行时类型的对象。基于运行时的类名（字符串），如何将 ANY 对象转换为实际对象？

我尝试使用 Class.forName 将类名转换为类对象

val clazz = Class.forName("my.package.Animal")
val any: Any = Animal(1, "simba")
any.asInstanceOf[clazz] // Compilation Error // Looking for a solution

标签： javascalareflectionscala-reflect

解决方案

尝试使用

  • 编译器工具箱

    package my.package

import scala.tools.reflect.ToolBox
import scala.reflect.runtime.universe._

case class Animal(id: Int, name: String)

object App {    
  val any: Any = Animal(1, "simba")
  val className = "my.package.Animal"

  val mirror = runtimeMirror(getClass.getClassLoader)
  val tb = mirror.mkToolBox()
  tb.eval(tb.parse(
    s"""
      import my.package.App._
      val animal = any.asInstanceOf[$className]
      println(animal.id)
      println(animal.name)
    """))
}

libraryDependencies += scalaOrganization.value % "scala-reflect" % scalaVersion.value

libraryDependencies += scalaOrganization.value % "scala-compiler" % scalaVersion.value

  • 或 Scala 反射

    import scala.reflect.runtime.universe._

val mirror = runtimeMirror(getClass.getClassLoader)
val classSymbol = mirror.staticClass(className)
val typ = classSymbol.toType
val idMethodSymbol = typ.decl(TermName("id")).asMethod
val nameMethodSymbol = typ.decl(TermName("name")).asMethod
val instanceMirror = mirror.reflect(any)
val idMethodMirror = instanceMirror.reflectMethod(idMethodSymbol)
val nameMethodMirror = instanceMirror.reflectMethod(nameMethodSymbol)
println(idMethodMirror())
println(nameMethodMirror())

libraryDependencies += scalaOrganization.value % "scala-reflect" % scalaVersion.value

  • 或 Java 反射

    val clazz = Class.forName(className)
val idMethod = clazz.getMethod("id")
val nameMethod = clazz.getMethod("name")
println(idMethod.invoke(any))
println(nameMethod.invoke(any))

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