【设计模式】第23节：行为型模式之“策略模式”

一、简介

策略模式：定义一族算法类，将每个算法分别封装起来，让它们可以互相替换。策略模式可以使算法的变化独立于使用它们的客户端（这里的客户端代指使用算法的代码）。

二、适用场景

• 动态选择算法
• 多种类似的行为

三、UML类图

四、案例

根据成年人、青年、小孩的不同计算不同的价格。

package main

import "fmt"

type PricingStrategy interface {
	CalculatePrice(price float64) float64
}

type ChildrenPricingStrategy struct {
}

func NewChildrenPricingStrategy() *ChildrenPricingStrategy {
	return &ChildrenPricingStrategy{}
}

func (s *ChildrenPricingStrategy) CalculatePrice(price float64) float64 {
	return price * 0.5
}

type AdultPricingStrategy struct {
}

func NewAdultPricingStrategy() *AdultPricingStrategy {
	return &AdultPricingStrategy{}
}

func (s *AdultPricingStrategy) CalculatePrice(price float64) float64 {
	return price
}

type SeniorPricingStrategy struct {
}

func NewSeniorPricingStrategy() *SeniorPricingStrategy {
	return &SeniorPricingStrategy{}
}

func (s *SeniorPricingStrategy) CalculatePrice(price float64) float64 {
	return price * 0.8
}

type PriceCalculator struct {
	Strategy PricingStrategy
}

func NewPriceCalculator(strategy PricingStrategy) *PriceCalculator {
	return &PriceCalculator{Strategy: strategy}
}

func (pc *PriceCalculator) Calculator(price float64) float64 {
	return pc.Strategy.CalculatePrice(price)
}

func main() {
	calculator := NewPriceCalculator(NewChildrenPricingStrategy())
	fmt.Printf("Children price: %v\n", calculator.Calculator(100))

	calculator = NewPriceCalculator(NewAdultPricingStrategy())
	fmt.Printf("Adult price: %v\n", calculator.Calculator(100))

	calculator = NewPriceCalculator(NewSeniorPricingStrategy())
	fmt.Printf("Senior price: %v\n", calculator.Calculator(100))
}