|NO.Z.00071|——————————|BigDataEnd|——|Hadoop&Scala.V03|——|Scala.v03|隐式机制|隐式转换函数.v02|

一、隐式转换函数

### --- 隐式转换案例

~~~     隐式转换案例：特殊售票窗口（只接受特殊人群买票，比如学生、老人等），
~~~     其他人不能在特殊售票窗口买票。

class SpecialPerson(var name: String)
class Older(var name: String)
class Student(var name: String)
class Worker(var name: String)
object ImplicitDemoTwo {
    def buySpecialTickWindow(person: SpecialPerson): Unit = {
        if (peron != null) {
            println(person.name + "购买了一张特殊票！")
        } else {
        println("你不是特殊人群，不能在此买票！")
}
}
//隐式转换函数
//注意：any参数的类型是Any
implicit def any2SpecialPerson(any: Any): SpecialPerson = {
    any match {
    case any: Older => new SpecialPerson(any.asInstanceOf[Older].name)
    case any: Student => new SpecialPerson(any.asInstanceOf[Student].name)
    case _ => null
}
}
def main(args: Array[String]): Unit = {
    val stu = new Student("jacky")
    val older = new Older("old man")
    val worker = new Worker("tom")
    ImplicitDemoTwo.buySpecialTickWindow(stu)
    ImplicitDemoTwo.buySpecialTickWindow(older)
    ImplicitDemoTwo.buySpecialTickWindow(worker)
    }
}

二、编程实现

### --- 编程代码

package yanqi.cn.part10

class SpecialPerson(var name: String)

class Older(var name: String)

class Student(var name: String)

class Worker(var name: String)

object ImplicitDemoTwo {
  def buySpecialTickWindow(person: SpecialPerson): Unit = {
    if (person != null) {
      println(person.name + "购买了一张特殊票！")
    } else {
      println("你不是特殊人群，不能在此购票！")
    }
  }

  //定义一个隐式转换函数
  implicit def any2SpecialPerson(any: Any): SpecialPerson = {
    any match {
      case any: Older => new SpecialPerson(any.asInstanceOf[Older].name)
      case any: Student => new SpecialPerson(any.asInstanceOf[Student].name)
      case _ => null
    }
  }

  def main(args: Array[String]): Unit = {
    val stu = new Student("jacky")
    val older = new Older("old man")
    val worker = new Worker("lisi")

    buySpecialTickWindow(stu)
    buySpecialTickWindow(older)
    buySpecialTickWindow(worker)
  }
}

### --- 编译打印

D:\JAVA\jdk1.8.0_231\bin\java.exe "-javaagent:D:\IntelliJIDEA\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=61235:D:\IntelliJIDEA\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath D:\JAVA\jdk1.8.0_231\jre\lib\charsets.jar;D:\JAVA\jdk1.8.0_231\jre\lib\deploy.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\access-bridge-64.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\cldrdata.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\dnsns.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\jaccess.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\jfxrt.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\localedata.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\nashorn.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunec.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunjce_provider.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunmscapi.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunpkcs11.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\zipfs.jar;D:\JAVA\jdk1.8.0_231\jre\lib\javaws.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jce.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jfr.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jfxswt.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jsse.jar;D:\JAVA\jdk1.8.0_231\jre\lib\management-agent.jar;D:\JAVA\jdk1.8.0_231\jre\lib\plugin.jar;D:\JAVA\jdk1.8.0_231\jre\lib\resources.jar;D:\JAVA\jdk1.8.0_231\jre\lib\rt.jar;E:\NO.Z.10000——javaproject\NO.Z.00002.Hadoop\ScalaPro\out\production\ScalaPro;D:\JAVA\scala-2.12.2\lib\scala-library.jar;D:\JAVA\scala-2.12.2\lib\scala-reflect.jar yanqi.cn.part10.ImplicitDemoTwo
jacky购买了一张特殊票！
old man购买了一张特殊票！
你不是特殊人群，不能在此购票！

Process finished with exit code 0

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Walter Savage Landor:strove with none,for none was worth my strife.Nature I loved and, next to Nature, Art:I warm'd both hands before the fire of life.It sinks, and I am ready to depart

                                                                                                                                                   ——W.S.Landor

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