Go设计模式之代理模式讲解和代码示例

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

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
}

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"
}

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)
}