Kotlin 中的享元模式(Flyweight Pattern)是一种用于性能优化的设计模式,它通过共享技术来有效地支持大量细粒度对象的复用
interface Flyweight {
fun operation(extrinsicState: Any)
}
class ConcreteFlyweight : Flyweight {
private val intrinsicState = mutableMapOf<String, String>()
fun setIntrinsicState(key: String, value: String) {
intrinsicState[key] = value
}
override fun operation(extrinsicState: Any) {
println("Object with intrinsic state ${intrinsicState} and external state $extrinsicState")
}
}
class FlyweightFactory {
private val flyweights = mutableMapOf<String, Flyweight>()
fun getFlyweight(key: String): Flyweight {
return flyweights.getOrPut(key) { ConcreteFlyweight() }
}
}
fun main() {
val factory = FlyweightFactory()
val flyweight1 = factory.getFlyweight("key1")
flyweight1.setIntrinsicState("state1", "value1")
flyweight1.operation("externalState1")
val flyweight2 = factory.getFlyweight("key1")
flyweight2.setIntrinsicState("state2", "value2")
flyweight2.operation("externalState2")
}
在这个例子中,ConcreteFlyweight
类实现了 Flyweight
接口,并定义了一个用于存储内部状态的数据结构。FlyweightFactory
类负责管理享元对象的创建和存储。在客户端代码中,我们通过享元工厂获取享元对象,并设置其内部状态。然后,我们可以使用这些对象执行操作,而无需创建新的对象。这样就实现了享元模式,从而提高了性能。