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代理

Go 代理模式讲解和代码示例

代理是一种结构型设计模式 让你能提供真实服务对象的替代品给客户端使用 代理接收客户端的请求并进行一些处理 访问控制和缓存等 然后再将请求传递给服务对象

代理对象拥有和服务对象相同的接口 这使得当其被传递给客户端时可与真实对象互换

概念示例

Nginx 这样的 Web 服务器可充当应用程序服务器的代理

  • 提供了对应用程序服务器的受控访问权限
  • 可限制速度
  • 可缓存请求

server.go: 主体

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: 真实主体

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: 客户端代码

package main

import "fmt"

func main() {

	nginxServer := newNginxServer()
	appStatusURL := "/app/status"
	createuserURL := "/create/user"

	httpCode, body := nginxServer.handleRequest(appStatusURL, "GET")
	fmt.Printf("\nUrl: %s\nHttpCode: %d\nBody: %s\n", appStatusURL, httpCode, body)

	httpCode, body = nginxServer.handleRequest(appStatusURL, "GET")
	fmt.Printf("\nUrl: %s\nHttpCode: %d\nBody: %s\n", appStatusURL, httpCode, body)

	httpCode, body = nginxServer.handleRequest(appStatusURL, "GET")
	fmt.Printf("\nUrl: %s\nHttpCode: %d\nBody: %s\n", appStatusURL, httpCode, body)

	httpCode, body = nginxServer.handleRequest(createuserURL, "POST")
	fmt.Printf("\nUrl: %s\nHttpCode: %d\nBody: %s\n", appStatusURL, httpCode, body)

	httpCode, body = nginxServer.handleRequest(createuserURL, "GET")
	fmt.Printf("\nUrl: %s\nHttpCode: %d\nBody: %s\n", appStatusURL, httpCode, body)
}

output.txt: 执行结果

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

代理在其他编程语言中的实现

Java 代理模式讲解和代码示例 C# 代理模式讲解和代码示例 C++ 代理模式讲解和代码示例 PHP 代理模式讲解和代码示例 Python 代理模式讲解和代码示例 Ruby 代理模式讲解和代码示例 Swift 代理模式讲解和代码示例 TypeScript 代理模式讲解和代码示例