快捷導(dǎo)航

Go設(shè)計(jì)模式之代理模式講解和代碼示例

更新時(shí)間：2023年07月24日 08:22:16 作者：demo007x

這篇文章主要介紹了Go代理模式，代理是一種結(jié)構(gòu)型設(shè)計(jì)模式，讓你能提供真實(shí)服務(wù)對(duì)象的替代品給客戶端使用，本文將對(duì)Go代理模式進(jìn)行講解以及代碼示例,需要的朋友可以參考下

Go 代理模式講解和代碼示例

代理是一種結(jié)構(gòu)型設(shè)計(jì)模式，讓你能提供真實(shí)服務(wù)對(duì)象的替代品給客戶端使用。代理接收客戶端的請(qǐng)求并進(jìn)行一些處理（訪問控制和緩存等），然后再將請(qǐng)求傳遞給服務(wù)對(duì)象。

代理對(duì)象擁有和服務(wù)對(duì)象相同的接口，這使得當(dāng)其被傳遞給客戶端時(shí)可與真實(shí)對(duì)象互換。

概念示例

Nginx 這樣的 Web 服務(wù)器可充當(dāng)應(yīng)用程序服務(wù)器的代理：

提供了對(duì)應(yīng)用程序服務(wù)器的受控訪問權(quán)限。
可限制速度。
可緩存請(qǐng)求。

server.go: 主體

package main
type server interface {
	handleRequest(string, string) (int, string)
}

nginx.go: 代理

package main
type Nginx struct {
	application       *Application
	maxAllowedRequest int
	rateLimiter       map[string]int
}
func newNginxServer() *Nginx {
	return &Nginx{
		application:       &Application{},
		maxAllowedRequest: 2,
		rateLimiter:       make(map[string]int),
	}
}
func (n *Nginx) handleRequest(url, method string) (int, string) {
	allowed := n.checkRateLimiting(url)
	if !allowed {
		return 403, "Not Allowed"
	}
	return n.application.handleRequest(url, method)
}
func (n *Nginx) checkRateLimiting(url string) bool {
	if n.rateLimiter[url] == 0 {
		n.rateLimiter[url] = 1
	}
	if n.rateLimiter[url] > n.maxAllowedRequest {
		return false
	}
	n.rateLimiter[url] = n.rateLimiter[url] + 1
	return true
}

application.go: 真實(shí)主體

package main
type Application struct{}
func (a *Application) handleRequest(url, method string) (int, string) {
	if url == "/app/status" && method == "GET" {
		return 200, "ok"
	}
	if url == "/create/user" && method == "POST" {
		return 201, "user created"
	}
	return 404, "Not OK"
}

main.go: 客戶端代碼

package main
import "fmt"
func main() {
	nginxServer := newNginxServer()
	appStatusURL := "/app/status"
	createuserURL := "/create/user"
	httpCode, msg := nginxServer.handleRequest(appStatusURL, "GET")
	fmt.Printf("\nUrl: %s\nHttpCode: %d\nBody: %s\n", appStatusURL, httpCode, msg)
	httpCode, msg = nginxServer.handleRequest(appStatusURL, "GET")
	fmt.Printf("\nUrl: %s\nHttpCode: %d\nBody: %s\n", appStatusURL, httpCode, msg)
	httpCode, msg = nginxServer.handleRequest(appStatusURL, "GET")
	fmt.Printf("\nUrl: %s\nHttpCode: %d\nBody: %s\n", appStatusURL, httpCode, msg)
	httpCode, msg = nginxServer.handleRequest(createuserURL, "POST")
	fmt.Printf("\nUrl: %s\nHttpCode: %d\nBody: %s\n", appStatusURL, httpCode, msg)
	httpCode, msg = nginxServer.handleRequest(createuserURL, "GET")
	fmt.Printf("\nUrl: %s\nHttpCode: %d\nBody: %s\n", appStatusURL, httpCode, msg)
}

output.txt: 執(zhí)行結(jié)果

Url: /app/status
HttpCode: 200
Body: ok

Url: /app/status
HttpCode: 200
Body: ok

Url: /app/status
HttpCode: 403
Body: Not Allowed

Url: /app/status
HttpCode: 201
Body: user created

Url: /app/status
HttpCode: 404
Body: Not OK