Golang代理模式与访问控制实现解析

// 定义被代理对象需实现的行为
type Service interface {
    DoWork() string
    Shutdown() error
}

// 真实服务（被代理者）
type RealService struct{}

func (r *RealService) DoWork() string { return "real work done" }
func (r *RealService) Shutdown() error { return nil }

type LoggingProxy struct {
    service Service // 组合，非继承
}

func (p *LoggingProxy) DoWork() string {
    fmt.Println("→ logging: before DoWork")
    result := p.service.DoWork()
    fmt.Println("← logging: after DoWork")
    return result
}

func (p *LoggingProxy) Shutdown() error {
    fmt.Println("→ logging: shutting down...")
    return p.service.Shutdown()
}

svc := &RealService{}
proxy := &LoggingProxy{service: svc}
fmt.Println(proxy.DoWork()) // 自动触发日志

type WorkFunc func() string

func WithAuthCheck(f WorkFunc) WorkFunc {
    return func() string {
        if !isUserAuthorized() {
            return "access denied"
        }
        return f()
    }
}

// 使用
realDo := func() string { return "work" }
securedDo := WithAuthCheck(realDo)
fmt.Println(securedDo()) // 先校验，再执行