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class Human{
println("Human")
}
trait TTeacher extends Human {
println("TTeacher")
def teach
}
trait PianoPlayer extends Human {
println("PianoPlayer")
def playPiano = {println("I am playing piano. ")}
}
class PianoTeacher extends Human with TTeacher with PianoPlayer { //构造PianoTeacher实例时，按照从左至右的顺序依次完成，仅构造一次
override def teach = {println("I am training students. ")}
}
object UseTrait extends App{
val t1 = new PianoTeacher
t1.playPiano
t1.teach
}

结果：
Human
TTeacher
PianoPlayer
I am playing piano.
I am training students.

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//AOP
trait Action {
def doAction
}
trait TBeforeAfter extends Action {
abstract override def doAction {
println("Initialization")
super.doAction //因为调用了父类的抽象方法，所以本方法也是抽象的。super.doAction最终会在子类Work中实现，有点类似于模板方法设计模式。
println("Destroyed")
}
}
class Work extends Action{
override def doAction = println("Working...")
}
object UseTrait extends App{
val work = new Work with TBeforeAfter
work.doAction
}

结果：
Initialization
Working...
Destroyed

ITPub博客

Scala多继承以及AOP