5分钟学会Android设计模式之策略模式StrategyPattern教程

class AnimatedView @JVMOverloads constructor(
    context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {
    var animationType: String = "translate"
    fun startAnimation() {
        when (animationType) {
            "translate" -> {
                // 实现平移动画
            }
            "rotate" -> {
                // 实现旋转动画
            }
            "scale" -> {
                // 实现缩放动画
            }
            else -> {
                throw IllegalArgumentException("Invalid animation type")
            }
        }
        invalidate()
    }
}

animatedView.apply {
    animationType = "translate"
}.startAnimation()
animatedView().apply {
    animationType = "rotate"
}.startAnimation()

interface AnimationStrategy {
    fun applyAnimation(view: View)
}

private var animationStrategy: AnimationStrategy? = null

override fun onDraw(canvas: Canvas?) {
    super.onDraw(canvas)
    if (animationStrategy != null) {
        animationStrategy!!.applyAnimation(this)
    }
}

class TranslateAnimationStrategy : AnimationStrategy {
    override fun applyAnimation(view: View) {
        // 实现平移动画
    }
}
class RotateAnimationStrategy : AnimationStrategy {
    override fun applyAnimation(view: View) {
        // 实现旋转动画
    }
}
class ScaleAnimationStrategy : AnimationStrategy {
    override fun applyAnimation(view: View) {
        // 实现缩放动画
    }
}

animatedView.apply {
    animationStrategy = TranslateAnimationStrategy() // 执行平移动画
    //or
    animationStrategy = RotateAnimationStrategy() // 执行旋转动画
    //or
    animationStrategy = ScaleAnimationStrategy()// 执行缩放动画
}

class AnimatedView @JvmOverloads constructor(
    context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : View(context, attrs, defStyleAttr) {
    var animationStrategy: AnimationStrategy? = null
        set(value) {
            field = value
            invalidate()
        }
    override fun onDraw(canvas: Canvas?) {
        super.onDraw(canvas)
        animationStrategy?.applyAnimation(this)
    }
}