type DiscountStrategy interface {
    Calculate(price float64) float64
}

type NormalUser struct{}
<p>func (n *NormalUser) Calculate(price float64) float64 {
return price // 无折扣
}</p><p>type VIPUser struct{}</p><p>func (v <em>VIPUser) Calculate(price float64) float64 {
return price </em> 0.9 // 9折
}</p><p>type SVIPUser struct{}</p><p>func (s <em>SVIPUser) Calculate(price float64) float64 {
return price </em> 0.7 // 7折
}</p>

type PriceCalculator struct {
    strategy DiscountStrategy
}
<p>func (p *PriceCalculator) SetStrategy(s DiscountStrategy) {
p.strategy = s
}</p><p>func (p *PriceCalculator) GetFinalPrice(price float64) float64 {
if p.strategy == nil {
panic("未设置策略")
}
return p.strategy.Calculate(price)
}</p>

calculator := &PriceCalculator{}
<p>calculator.SetStrategy(&VIPUser{})
fmt.Println(calculator.GetFinalPrice(100)) // 输出 90</p><p>calculator.SetStrategy(&SVIPUser{})
fmt.Println(calculator.GetFinalPrice(100)) // 输出 70</p>

func NewDiscountStrategy(userType string) DiscountStrategy {
    switch userType {
    case "normal":
        return &NormalUser{}
    case "vip":
        return &VIPUser{}
    case "svip":
        return &SVIPUser{}
    default:
        return &NormalUser{}
    }
}

userType := "svip"
calculator.SetStrategy(NewDiscountStrategy(userType))
finalPrice := calculator.GetFinalPrice(200)