Go模仿gin自定义中间件

方式1

package main

import (
	"fmt"
	"net/http"
)

// 中间件函数类型
type MiddlewareFunc func(http.HandlerFunc) http.HandlerFunc

// 自定义中间件1
func LoggerMiddleware(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, req *http.Request) {
		fmt.Println("Logging:", req.Method, req.URL.Path)
		next(w, req)
	}
}

// 自定义中间件2
func LoggerMiddleware2(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, req *http.Request) {
		fmt.Println("Logging2:", req.Method, req.URL.Path)
		next(w, req)
	}
}

// 使用中间件
func UseMiddleware(handler http.HandlerFunc, middleware ...MiddlewareFunc) http.HandlerFunc {
	for i := len(middleware) - 1; i >= 0; i-- {
		handler = middleware[i](handler)
	}
	return handler
}

// 处理请求的处理程序
func myHandler(w http.ResponseWriter, req *http.Request) {
	fmt.Println("do handler")
	w.Write([]byte("Hello, World!"))
}

func main() {
	// 创建一个个中间件处理程序
	handlerWithMiddleware := UseMiddleware(myHandler, LoggerMiddleware, LoggerMiddleware2)

	http.HandleFunc("/", handlerWithMiddleware)

	fmt.Println("Server is running on localhost:8080")
	http.ListenAndServe(":8080", nil)
}

方式2 推荐

package main

import (
	"fmt"
	"math"
)

const abortIndex = math.MaxInt8 / 2

// 中间件结构体
type Context struct {
	Handlers []func(c *Context) //需要执行的方法切片
	index    int8               //偏移量
}

// 注册方法到中间件
func (this *Context) Use(f func(c *Context)) {
	this.Handlers = append(this.Handlers, f)
}

// 执行下一个方法
func (this *Context) Next() {
	if this.index < int8(len(this.Handlers)) {
		this.index++
		this.Handlers[this.index](this)
	}
}

// 执行handlers里面的第一个方法
func (this *Context) Run() {
	this.Handlers[0](this)
}

func (this *Context) GET(path string, f func(c *Context)) {
	this.Handlers = append(this.Handlers, f)
}

// 终止
func (this *Context) Abort() {
	this.index = abortIndex
}

//主方法
func main() {
	c := &Context{}
	c.Use(MiddlewareOne())
	c.Use(MiddlewareTwo())
	c.GET("/get", func(c *Context) {
		fmt.Println("执行具体方法")
	})
	c.Run()
}

//中间件一
func MiddlewareOne() func(c *Context) {
	return func(c *Context) {
		fmt.Println("MiddlerOne Start")
		c.Next()
		fmt.Println("MiddlerOne End")
	}
}
//中间件二
func MiddlewareTwo() func(c *Context) {
	return func(c *Context) {
		fmt.Println("MiddlerTwo Start")
		c.Next()
		fmt.Println("MiddlerTwo End")
	}
}
//中间件三
func MiddlewareThree() func(c *Context) {
	return func(c *Context) {
		fmt.Println("MiddlerThree Start")
		c.Next()
		fmt.Println("MiddlerThree End")
	}
}