trait 继承的Demo

原创于 2017-09-23 17:31:06 发布 · 170 阅读

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本文介绍了一个使用Scala实现的日志记录系统，该系统通过特质实现了打印和加密日志的功能。文章展示了如何定义特质并让类同时具备打印明文日志和加密后日志的能力。

trait Logger {
  def log(msg: String) {}
}

trait PrinterLogger extends Logger {
  val v = 24

  override def log(msg: String): Unit = {
    println(msg)
  }
}

trait CryptoLogger extends Logger {
  val key = 3

  override def log(msg: String): Unit = {
    val ceasarMsg = for (c <- msg) yield c match {
      case a if a >= 'A' && a <= 'Z' => applyKey(a, 'A', 26)
      case a if a >= '0' && a <= '9' => applyKey(a, '0', 10)
      case _ => c
    }
    super.log(ceasarMsg)
  }

  private def applyKey(c: Char, r: Char, l: Int): Char = {
    ((c - r + key) % l + r).toChar
  }
}

class Person(private val _name: String) extends {
  override val key = 9
  override val v = 36
} with PrinterLogger with CryptoLogger {
  def name = {
    log(_name)
    _name
  }
}

val JohnSmith = new Person("John Smith")
println(JohnSmith.key)
println(JohnSmith.v)
JohnSmith.name