本节主要内容：
Actor API解析Actor中的主要成员变量和方法定义如下：
package akka.actor trait Actor extends scala.AnyRef { type Receive = akka.actor.Actor.Receive //context变量暴露当前Actor的上下文信息及当前消息 implicit val context : akka.actor.ActorContext = { /* compiled code */ } //self作为当前ActorRef的引用 implicit final val self : akka.actor.ActorRef = { /* compiled code */ } //当前Actor接收到最后一条消息对应的消息发送者(Actor） final def sender() : akka.actor.ActorRef = { /* compiled code */ } //receive方法，抽象方法，定义Actor的行为逻辑 def receive : akka.actor.Actor.Receive //内部使用API protected[akka] def aroundReceive(receive : akka.actor.Actor.Receive, msg : scala.Any) : scala.Unit = { /* compiled code */ } protected[akka] def aroundPreStart() : scala.Unit = { /* compiled code */ } protected[akka] def aroundPostStop() : scala.Unit = { /* compiled code */ } protected[akka] def aroundPreRestart(reason : scala.Throwable, message : scala.Option[scala.Any]) : scala.Unit = { /* compiled code */ } protected[akka] def aroundPostRestart(reason : scala.Throwable) : scala.Unit = { /* compiled code */ } //监督策略，用于Actor容错处理 def supervisorStrategy : akka.actor.SupervisorStrategy = { /* compiled code */ } //Hook方法，用于Actor生命周期监控 @scala.throws[T](classOf[scala.Exception]) def preStart() : scala.Unit = { /* compiled code */ } @scala.throws[T](classOf[scala.Exception]) def postStop() : scala.Unit = { /* compiled code */ } @scala.throws[T](classOf[scala.Exception]) def preRestart(reason : scala.Throwable, message : scala.Option[scala.Any]) : scala.Unit = { /* compiled code */ } @scala.throws[T](classOf[scala.Exception]) def postRestart(reason : scala.Throwable) : scala.Unit = { /* compiled code */ } //发送给Actor的消息，Actor没有定义相应的处理逻辑时，会调用此方法 def unhandled(message : scala.Any) : scala.Unit = { /* compiled code */ } } object Actor extends scala.AnyRef { type Receive = scala.PartialFunction[scala.Any, scala.Unit] //空的行为逻辑 @scala.SerialVersionUID(1) object emptyBehavior extends scala.AnyRef with akka.actor.Actor.Receive { def isDefinedAt(x : scala.Any) : scala.Boolean = { /* compiled code */ } def apply(x : scala.Any) : scala.Nothing = { /* compiled code */ } } //Sender为null @scala.SerialVersionUID(1) final val noSender : akka.actor.ActorRef = { /* compiled code */ } }代码运行结果：
[INFO] [04/02/2016 17:04:49.607] [main] [ActorSystem(MyActorSystem)] 准备向myactor发送消息 [INFO] [04/02/2016 17:04:49.607] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor] preStart() in FirstActor [INFO] [04/02/2016 17:04:49.607] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor] received test [INFO] [04/02/2016 17:04:49.607] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor] received 123 [INFO] [04/02/2016 17:04:49.608] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor/myChild] preStart() in MyActor [INFO] [04/02/2016 17:04:49.608] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor/myChild] received test [INFO] [04/02/2016 17:04:49.608] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor/myChild] received unknown message [INFO] [04/02/2016 17:04:54.616] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myChild] postStop() in MyActor [INFO] [04/02/2016 17:04:54.617] [MyActorSystem-akka.actor.default-dispatcher-3] [akka://MyActorSystem/user/firstActor] postStop() in FirstActor在代码
class FirstActor extends Actor with ActorLogging{ //通过context.actorOf方法创建Actor var child:ActorRef = _ //Hook方法，preStart()，Actor启动之前调用，用于完成初始化工作 override def preStart(): Unit ={ log.info("preStart() in FirstActor") //通过context上下文创建Actor child = context.actorOf(Props[MyActor], name = "myChild") } def receive = { //向MyActor发送消息 case x => child ! x;log.info("received "+x) } //Hook方法，postStop()，Actor停止之后调用，用于完成初始化工作 override def postStop(): Unit = { log.info("postStop() in FirstActor") } }中分别对postStop、preStart方法进行了重写，在preStart方法中通过代码
child = context.actorOf(Props[MyActor], name = "myChild")对成员变量child进行初始化，然后在postStop方法中使用
//通过context上下文停止MyActor的运行 context.stop(child)停止MyActor的运行。在使用代码
//创建FirstActor对象 val myactor = system.actorOf(Props[FirstActor], name = "firstActor")创建FirstActor时，便会调用preStart方法完成MyActor的创建，因此首先会执行FirstActor中的preStart()方法
dispatcher-4] [akka://MyActorSystem/user/firstActor] preStart() in FirstActor然后在创建MyActor时执行MyActor中定义的preStart方法
[INFO] [04/02/2016 17:04:49.608] [MyActorSystem-akka.actor.default-dispatcher-2] [akka://MyActorSystem/user/firstActor/myChild] preStart() in MyActor在执行
//关闭ActorSystem，停止程序的运行 system.shutdown()FirstActor作为MyActor的Supervisor，会先停止MyActor，再停止自身，因此先调用MyActor的postStop方法，再调用FirstActor的postStop方法。
整体代码如下：
/* *Actor API:成员变量self及sender()方法的使用 */ object Example_05 extends App{ import akka.actor.Actor import akka.actor.ActorSystem import akka.actor.Props class FirstActor extends Actor with ActorLogging{ //通过context.actorOf方法创建Actor var child:ActorRef = _ override def preStart(): Unit ={ log.info("preStart() in FirstActor") //通过context上下文创建Actor child = context.actorOf(Props[MyActor], name = "myActor") } def receive = { //向MyActor发送消息 case x => child ! x;log.info("received "+x) } } class MyActor extends Actor with ActorLogging{ self!"message from self reference" def receive = { case "test" => log.info("received test");sender()!"message from MyActor" case "message from self reference"=>log.info("message from self refrence") case _ => log.info("received unknown message"); } } val system = ActorSystem("MyActorSystem") val systemLog=system.log //创建FirstActor对象 val myactor = system.actorOf(Props[FirstActor], name = "firstActor") systemLog.info("准备向myactor发送消息") //向myactor发送消息 myactor!"test" myactor! 123 Thread.sleep(5000) //关闭ActorSystem，停止程序的运行 system.shutdown() }运行结果：
[INFO] [04/02/2016 18:40:37.805] [main] [ActorSystem(MyActorSystem)] 准备向myactor发送消息 [INFO] [04/02/2016 18:40:37.805] [MyActorSystem-akka.actor.default-dispatcher-3] [akka://MyActorSystem/user/firstActor] preStart() in FirstActor [INFO] [04/02/2016 18:40:37.806] [MyActorSystem-akka.actor.default-dispatcher-3] [akka://MyActorSystem/user/firstActor] received test [INFO] [04/02/2016 18:40:37.806] [MyActorSystem-akka.actor.default-dispatcher-3] [akka://MyActorSystem/user/firstActor] received 123 [INFO] [04/02/2016 18:40:37.806] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] received test [INFO] [04/02/2016 18:40:37.806] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] message from self refrence [INFO] [04/02/2016 18:40:37.806] [MyActorSystem-akka.actor.default-dispatcher-3] [akka://MyActorSystem/user/firstActor] received message from MyActor [INFO] [04/02/2016 18:40:37.806] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] received unknown message [INFO] [04/02/2016 18:40:37.806] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] received unknown message代码：
class MyActor extends Actor with ActorLogging{ self!"message from self reference" def receive = { case "test" => log.info("received test");sender()!"message from MyActor" case "message from self reference"=>log.info("message from self refrence") case _ => log.info("received unknown message"); } }中使用
self!"message from self reference"向自身发送了一条消息，receive方法通过
case "message from self reference"=>log.info("message from self refrence")对这条消息进行处理。receive方法在处理
def receive = { case "test" => log.info("received test");sender()!"message from MyActor"“test”消息时，会调用
sender()!"message from MyActor"向sender（本例中为FirstActor）发送”message from MyActor”消息，FirstActor使用
def receive = { //向MyActor发送消息 case x => child ! x;log.info("received "+x) }处理消息时又向MyActor回送该消息，因此最终的输出有两个unknown message，分别对应123和”message from MyActor”
[INFO] [04/02/2016 18:40:37.806] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] received unknown message [INFO] [04/02/2016 18:40:37.806] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor/myActor] received unknown messageunhandled方法用于处理没有被receive方法处理的消息，下面的代码给出的是当不重写unhandled方法时的代码
/* *Actor API:unhandled方法 */ object Example_06 extends App{ import akka.actor.Actor import akka.actor.ActorSystem import akka.actor.Props class FirstActor extends Actor with ActorLogging{ def receive = { //向MyActor发送消息 case "test" => log.info("received test") } } val system = ActorSystem("MyActorSystem") val systemLog=system.log //创建FirstActor对象 val myactor = system.actorOf(Props[FirstActor], name = "firstActor") systemLog.info("准备向myactor发送消息") //向myactor发送消息 myactor!"test" myactor! 123 Thread.sleep(5000) //关闭ActorSystem，停止程序的运行 system.shutdown() }代码输出：
[INFO] [04/02/2016 19:14:11.992] [main] [ActorSystem(MyActorSystem)] 准备向myactor发送消息 [INFO] [04/02/2016 19:14:11.992] [MyActorSystem-akka.actor.default-dispatcher-3] [akka://MyActorSystem/user/firstActor] received test不难看出，对于
myactor! 123发送的这条消息没有被处理，没有任何的处理逻辑。在实际开发过程中，可能会对不能被处理的消息增加一些应对逻辑，此时可以重写unhandled方法，代码如下：
/* *Actor API:unhandled方法的使用 */ object Example_06 extends App{ import akka.actor.Actor import akka.actor.ActorSystem import akka.actor.Props class FirstActor extends Actor with ActorLogging{ def receive = { //向MyActor发送消息 case "test" => log.info("received test") } //重写unhandled方法 override def unhandled(message: Any): Unit = { log.info("unhandled message is {}",message) } } val system = ActorSystem("MyActorSystem") val systemLog=system.log //创建FirstActor对象 val myactor = system.actorOf(Props[FirstActor], name = "firstActor") systemLog.info("准备向myactor发送消息") //向myactor发送消息 myactor!"test" myactor! 123 Thread.sleep(5000) //关闭ActorSystem，停止程序的运行 system.shutdown() }代码输出结果：
[INFO] [04/02/2016 19:17:18.458] [main] [ActorSystem(MyActorSystem)] 准备向myactor发送消息 [INFO] [04/02/2016 19:17:18.458] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor] received test [INFO] [04/02/2016 19:17:18.458] [MyActorSystem-akka.actor.default-dispatcher-4] [akka://MyActorSystem/user/firstActor] unhandled message is 123其它如preRestart等方法的使用将在Akka容错部分进行讲解。
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