Scala反射生成一个伴生对象并调用apply方法

问题就在这里

trait TestTrait[T, R] extends (T => R) 

// Class implementing TestTrait. This is one class, there are a number of class implementing TestTrait
class TestClass(val input: Map[String, String])extends ConfigurableDomainExtractor[String, String] {
  override def apply(value: String): String = ???
}

// Companion Object
object TestClass {
 def apply(properties: Map[String, String]): TestClass = TestClass(properties)
}

我想做的是在util类中定义一个方法

class CreateInstance {
  def getInstance(fullyQualifiedClassName: String, properties: Map[String, String]): TestTrait = ???

// fullyQualifiedClassName is the name of the class that needs to be instantiated using its companion object. It can be TestClass or any class implementing TestTrait
// properties is the map that needs to be pass to the apply method of the companion object.


}

它将在传递类名时，通过首先获取一个伴随对象，然后调用传递映射的伴随对象上的apply来生成类实例，从而生成同一类的对象

我知道我们在scala有一些反映，我尝试了一些事情，但都没有用。以下是我尝试过的几件事

  import scala.reflect.runtime.universe

def getInstance(fullyQualifiedClassName: String, properties: Map[String, String]): TestTrait = {
val runtimeMirror = universe.runtimeMirror(getClass.getClassLoader)
    val module        = runtimeMirror.staticModule(fullyQualifiedClassName)
    val obj           = runtimeMirror.reflectModule(module)

      obj.instance
        .asInstanceOf[TestTrait[String, String]]
        .apply(properties)
        .asInstanceOf[TestTrait[String, String]]

}

有人能帮我完成

def getInstance

方法吗

试试Scala反射

import scala.reflect.runtime.universe
import scala.reflect.runtime.universe._

def getInstance(fullyQualifiedClassName: String, properties: Map[String, String]): TestTrait[String, String] = {
  val runtimeMirror = universe.runtimeMirror(getClass.getClassLoader)
  val objSymbol = runtimeMirror.staticModule(fullyQualifiedClassName)
  val objMirror = runtimeMirror.reflectModule(objSymbol)
  val obj = objMirror.instance
  val objTyp = objSymbol.typeSignature
  val methodSymbol = objTyp.decl(TermName("apply")).asMethod
  val instanceMirror = runtimeMirror.reflect(obj)
  val methodMirror = instanceMirror.reflectMethod(methodSymbol)
  methodMirror(properties).asInstanceOf[TestTrait[String, String]]
}

getInstance("pckg.App.TestClass", Map("a" -> "b"))

def getInstance(fullyQualifiedClassName: String, properties: Map[String, String]): TestTrait[String, String] = {
  val clazz = Class.forName(fullyQualifiedClassName)
  val moduleField = clazz.getDeclaredField("MODULE$")
  val obj = moduleField.get(null) // field MODULE$ is static
  val applyMethod = clazz.getDeclaredMethod("apply", classOf[Map[_, _]])
  applyMethod.invoke(obj, properties).asInstanceOf[TestTrait[String, String]]
}

getInstance("pckg.App$TestClass$", Map("a" -> "b"))

或Java反射

import scala.reflect.runtime.universe
import scala.reflect.runtime.universe._

def getInstance(fullyQualifiedClassName: String, properties: Map[String, String]): TestTrait[String, String] = {
  val runtimeMirror = universe.runtimeMirror(getClass.getClassLoader)
  val objSymbol = runtimeMirror.staticModule(fullyQualifiedClassName)
  val objMirror = runtimeMirror.reflectModule(objSymbol)
  val obj = objMirror.instance
  val objTyp = objSymbol.typeSignature
  val methodSymbol = objTyp.decl(TermName("apply")).asMethod
  val instanceMirror = runtimeMirror.reflect(obj)
  val methodMirror = instanceMirror.reflectMethod(methodSymbol)
  methodMirror(properties).asInstanceOf[TestTrait[String, String]]
}

getInstance("pckg.App.TestClass", Map("a" -> "b"))

def getInstance(fullyQualifiedClassName: String, properties: Map[String, String]): TestTrait[String, String] = {
  val clazz = Class.forName(fullyQualifiedClassName)
  val moduleField = clazz.getDeclaredField("MODULE$")
  val obj = moduleField.get(null) // field MODULE$ is static
  val applyMethod = clazz.getDeclaredMethod("apply", classOf[Map[_, _]])
  applyMethod.invoke(obj, properties).asInstanceOf[TestTrait[String, String]]
}

getInstance("pckg.App$TestClass$", Map("a" -> "b"))

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在这里，仅仅使用Java反射就足够了吗。。。？这要容易得多。@SethTisue如何使用Java反射API？