Golang责任链模式请求处理解析

package main

type Handler interface {
    SetNext(handler Handler)
    Handle(request string) string
}

type ConcreteHandler struct {
    next Handler
}

func (h *ConcreteHandler) SetNext(handler Handler) {
    h.next = handler
}

func (h *ConcreteHandler) Handle(request string) string {
    if h.next != nil {
        return h.next.Handle(request)
    }
    return "No handler can process this request."
}

type AuthHandler struct{ ConcreteHandler }

func (a *AuthHandler) Handle(request string) string {
    if request == "auth" {
        return "AuthHandler processed auth request"
    }
    return a.ConcreteHandler.Handle(request)
}

type LoggingHandler struct{ ConcreteHandler }

func (l *LoggingHandler) Handle(request string) string {
    if request == "log" {
        return "LoggingHandler processed log request"
    }
    return l.ConcreteHandler.Handle(request)
}

func main() {
    auth := &AuthHandler{}
    log := &LoggingHandler{}
    fallback := &ConcreteHandler{} // 终止节点

    auth.SetNext(log)
    log.SetNext(fallback)

    println(auth.Handle("auth")) // 输出：AuthHandler processed auth request
    println(auth.Handle("log"))  // 输出：LoggingHandler processed log request
    println(auth.Handle("unknown")) // 向后传递直至 fallback
}