自定义http服务+中间件案例

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"time"
)

// MiddlewareFunc 中间件的函数
type MiddlewareFunc func(ctx context.Context, req interface{}) (resp interface{}, err error)

// Middleware 构建中间件函数使用
type Middleware func(MiddlewareFunc) MiddlewareFunc

// LogFile LogFile
type LogFile struct {
	logName string
}

// buildMiddleWare 构建一个中间件函数
func buildMiddleWare(handle MiddlewareFunc) MiddlewareFunc {
	var chain []Middleware
	var LogFiler LogFile
	chain = append(chain, frontHook)
	chain = append(chain, newPrintLog(LogFiler))

	middle := buildChain(chain)
	return middle(handle)
}

// buildChain 构建链
/**
把中间件的数组构建成个链
最先执行的在最外层
next执行下一个  执行顺序和数组顺序相反
*/
func buildChain(chain []Middleware) Middleware {
	return func(next MiddlewareFunc) MiddlewareFunc {
		for i := len(chain) - 1; i >= 0; i-- {
			next = chain[i](next)
		}
		return next
	}
}

// frontHook 执行前置中间件
func frontHook(next MiddlewareFunc) MiddlewareFunc {
	return func(ctx context.Context, req interface{}) (resp interface{}, err error) {
		fmt.Println("执行前置中间件")
		startTime := time.Now().UnixNano() / 1e6
		resp, err = next(ctx, req) // 执行下一个
		if err != nil {
			log.Fatal(err)
			return
		}
		endTime := time.Now().UnixNano() / 1e6
		fmt.Println("函数执行时间为:", endTime-startTime)
		return
	}
}

// newPrintLog 打印日志中间件
func newPrintLog(LogFiler LogFile) Middleware {
	return func(next MiddlewareFunc) MiddlewareFunc {
		return func(ctx context.Context, req interface{}) (resp interface{}, err error) {
			fmt.Println("打印日志中间件")
			fmt.Println(LogFiler.logName, req)
			resp, err = next(ctx, req)
			return
		}
	}
}

// customHandler 自定义函数
func customHandler(ctx context.Context, req interface{}) (resp interface{}, err error) {
	resp = req
	fmt.Println("customHandle")
	time.Sleep(time.Second)
	return
}

// router router
func router(writer http.ResponseWriter, request *http.Request) {

	MiddlewareFunction := buildMiddleWare(customHandler)
	_, err := MiddlewareFunction(context.Background(), request)
	if err != nil {
		log.Fatal(err)
		return
	}

	_, _ = writer.Write([]byte("<h1 style='color:red;'>2023水一贴</h1>"))

}

func main() {

	//注册路由
	http.HandleFunc("/", router)
	//建立监听
	err := http.ListenAndServe(fmt.Sprintf("127.0.0.1:%d", 8089), nil)

	if err != nil {
		log.Fatal(err)
		return
	}

}