Centaur · September 5, 2016 06:39 · Sep 5, 2016
diff --git a/eventlisteners.scala b/eventlisteners.scala
@@ -0,0 +1,58 @@
+package org.snippets
+
+import scala.collection.mutable.ListBuffer
+import scala.reflect.ClassTag
+
+
+trait Event[T] {
+}
+
+trait EventListener[T] {
+  def onEvent(event: Event[T])
+}
+
+trait Listenable[T] {
+  val name: String
+  val listeners: ListBuffer[EventListener[T]]
+}
+
+object Event {
+  var cachedListenables: Map[ClassTag[_], Listenable[_]] = Map()
+
+  implicit def eventIsListenable[T: ClassTag]: Listenable[T] = {
+    val typ = implicitly[ClassTag[T]]
+    cachedListenables.get(typ) match {
+      case None =>
+        val newVal = new Listenable[T] {
+          override val name: String = s"Listeners of Event[${implicitly[ClassTag[T]]}]"
+          override val listeners: ListBuffer[EventListener[T]] = ListBuffer()
+        }
+        cachedListenables = cachedListenables.updated(typ, newVal)
+        newVal
+      case Some(l) => l.asInstanceOf[Listenable[T]]
+    }
+  }
+}
+
+
+object TypedEvents {
+
+  def dispatchEvent[T](event: Event[T])(implicit ev: Listenable[T]): Unit = {
+    val listeners = ev.listeners
+    println(s"Invoking ${ev.name} , ${ev.hashCode}(相同类型的Event应使用同一个listener集合)")
+
+    listeners.foreach(listener => {
+      listener.onEvent(event)
+    })
+  }
+
+
+  def main(args: Array[String]): Unit = {
+    import Event._
+    dispatchEvent(new Event[Int] {})
+    dispatchEvent(new Event[Int] {})
+    dispatchEvent(new Event[Int] {})
+    dispatchEvent(new Event[String] {})
+    dispatchEvent(new Event[String] {})
+  }
+}