大数据系列修炼-Scala课程107

大数据系列修炼-Scala课程107

核心内容:
1、Akka中的第二种消息发送方式以及Future使用代码实战详解

1、Akka中的第二种消息发送方式以及Future使用代码实战详解

1>this.getSender().tell(“message having received!”,this.getSelf());的具体的含义：
this.getSender()返回的是一个ActorRef的句柄，指向消息的发送者。 （如main方法所在的Actor）
this.getSelf()指向的是消息自身的发送者。(如Worker所在的Actor)
2>Patterns的三个参数:第一个参数是给哪个Actor发送消息、第二个参数是发送什么样的消息、第三个参数是超时时间
Future future = Patterns.ask(worker, “Spark and Hadoop scala and Java”, timeout);
3>我们常用future实例对象来接受对方Actor发送过来的结果，并且future接受到具体消息之后，可以用future提取出相应的结果。
4>Future对象其实是Java中后来推出的，在线程结束之后接受另外一个线程结果的一个对象。
5>TimeOut：等待对方Actor返回结果给future的超时时间。

实例程序1:

package com.test.scala.app;

import akka.actor.ActorRef;
import akka.actor.ActorSystem;
import akka.actor.Props;
import akka.actor.UntypedActor;
import akka.dispatch.Await;
import akka.dispatch.Future;
import akka.event.Logging;
import akka.event.LoggingAdapter;
import akka.pattern.Patterns;
import akka.util.Duration;
import akka.util.Timeout;

/** * 本程序模拟了Akka中send and receive的消息发送方式,caller----receiver */
class Worker extends UntypedActor
{
    //这句话我现在也不是太清楚
    private LoggingAdapter log = Logging.getLogger(getContext().system(),this);
    @Override
    public void onReceive(Object message) throws Exception
    {
        if(message instanceof String) //如果接受到的消息是String类型
        {
            Thread.sleep(3000);  //休眠3秒钟
            System.out.println(Thread.currentThread().getName()+"is going to work!!!");  //当前Actor即WorkerActor正在工作
            //输出main方法所在的Actor发送过来的消息---将消息打印出来
            System.out.println("The content of the received message is:" + message);
            //this.getSender指的是消息的发送者(main方法所在的Actor),this.geSelf指的是WorkActor
            this.getSender().tell("message having received!",this.getSelf());
            //输出消息发送者所在的具体路径(main方法所在Actor的具体路径)
            System.out.println("The sender's path="+this.getSender().path());
            //将当前Actor停止
            getContext().stop(this.getSelf());
            //将具体的信息打印出来
            log.info("|||{} has stopped",this.getSelf().path());
        }
    }
}
public class App
{
    public static void main(String[] args) throws Exception
    {
        System.out.println("The name of current thread is:" + Thread.currentThread().getName());  //即main方法所在线程的名字
        //创建一个ActorSystem容器：类似容器了
        ActorSystem system = ActorSystem.create("system");
        //在当前ActorSystem的基础上去创建一个WorkerActor
        ActorRef worker = system.actorOf(new Props(Worker.class), "WorkerActor");
        //用future等待消息的时间设置
        Timeout timeout = new Timeout(Duration.create(5, "seconds"));
        //用Patterns发送消息,并返回一个future
        //Patterns的三个参数:第一个参数是给哪个Actor发送消息、第二个参数是发送什么样的消息、第三个参数是超时时间
        Future<Object> future = Patterns.ask(worker, "Spark and Hadoop scala and Java", timeout);
        //用Await.result等待future的具体结果
        String result = (String) Await.result(future, timeout.duration());
        //将返回的具体消息打印出来
        System.out.println(result);
    }
}

程序运行结果:(呵呵，程序不知道为什么总是出现这个异常！)

"C:\Program Files (x86)\Java\jdk1.8.0_65\bin\java" -Didea.launcher.port=7542 "-Didea.launcher.bin.path=E:\Smart IDEA\IntelliJ IDEA Community Edition 2016.2.4\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\charsets.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\deploy.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\access-bridge-32.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\cldrdata.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\dnsns.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\jaccess.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\jfxrt.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\localedata.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\nashorn.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunec.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunjce_provider.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunmscapi.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\sunpkcs11.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\ext\zipfs.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\javaws.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jce.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jfr.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jfxswt.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\jsse.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\management-agent.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\plugin.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\resources.jar;C:\Program Files (x86)\Java\jdk1.8.0_65\jre\lib\rt.jar;E:\HelloScala\out\production\HelloTest;D:\SOFTWARE\scala\lib\scala-actors-migration.jar;D:\SOFTWARE\scala\lib\scala-actors.jar;D:\SOFTWARE\scala\lib\scala-library.jar;D:\SOFTWARE\scala\lib\scala-reflect.jar;D:\SOFTWARE\scala\lib\scala-swing.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\scala-library.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-actor-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-actor-migration-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-agent-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-beanstalk-mailbox-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-file-mailbox-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-kernel-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-mailboxes-common-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-mongo-mailbox-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-redis-mailbox-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-remote-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-sample-fsm-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-sample-hello-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-sample-hello-kernel-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-sample-remote-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-slf4j-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-testkit-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-transactor-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-zeromq-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\akka-zookeeper-mailbox-2.0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\beanstalk_client-1.4.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\bson-driver_2.9.0-1-0.2.9-1.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\commons-codec-1.4.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\commons-io-1.4.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\commons-io-2.0.1.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\commons-logging-1.1.1.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\commons-pool-1.5.6.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\config-0.3.1.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\dispatch-json_2.9.1-0.8.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\h2-lzf-1.0.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\httpclient-4.1.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\httpcore-4.1.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\jna-3.0.9.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\jnr-constants-0.8.2.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\log4j-1.2.14.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\mongo-driver_2.9.0-1-0.2.9-1.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\mongo-java-driver-2.7.1.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\netty-3.5.4.Final.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\objenesis-1.2.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\protobuf-java-2.4.1.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\redisclient_2.9.1-2.4.0.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\scala-stm_2.9.1-0.5.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\scalaj-collection_2.9.0-1-1.2.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\sjson_2.9.1-0.15.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\slf4j-api-1.6.4.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\util-core-1.12.2.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\zeromq-scala-binding_2.9.1-0.0.6.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\zkclient-0.3.jar;D:\SOFTWARE\akka\akka-2.0.5\lib\akka\zookeeper-3.4.0.jar;E:\Smart IDEA\IntelliJ IDEA Community Edition 2016.2.4\lib\idea_rt.jar" com.intellij.rt.execution.application.AppMain com.test.scala.app.App
The name of current thread is:main
Exception in thread "main" java.lang.NoSuchMethodError: scala.Predef$.augmentString(Ljava/lang/String;)Lscala/collection/immutable/StringOps; at akka.util.Duration$.<init>(Duration.scala:76)
    at akka.util.Duration$.<clinit>(Duration.scala) at akka.actor.ActorSystem$Settings.<init>(ActorSystem.scala:140)
    at akka.actor.ActorSystemImpl.<init>(ActorSystem.scala:449)
    at akka.actor.ActorSystem$.apply(ActorSystem.scala:111) at akka.actor.ActorSystem$.apply(ActorSystem.scala:93)
    at akka.actor.ActorSystem$.create(ActorSystem.scala:56) at akka.actor.ActorSystem.create(ActorSystem.scala) at com.test.scala.app.App.main(App.java:48) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:497) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147) Process finished with exit code 1 

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