golang gin/httpRouter框架路由中间件use的实现原理
package main
import (
"fmt"
"net/http"
"time"
)
// 声明一个中间件类型
type middleware func(handler http.Handler) http.Handler
// 定义一个路由
type Router struct {
middlewareChain []middleware
mux map[string]http.Handler
}
func NewRouter() *Router {
return &Router{
mux:make(map[string]http.Handler),
}
}
// 添加中间件
func (r *Router) Use (m middleware) {
r.middlewareChain = append(r.middlewareChain, m)
}
// 添加路由
func (r *Router) Add(route string, h http.Handler) {
var mergedHandler = h
for i := len(r.middlewareChain) - 1; i>=0; i-- {
// 倒序 循环构造中间件合集， 类似递归的方式 嵌套组合成一个方法
mergedHandler = r.middlewareChain[i](mergedHandler)
}
// 把最终合成的路由处理方法赋值
r.mux[route] = mergedHandler
}
// 实现 http.Hander 接口
func (r *Router) ServeHTTP(w http.ResponseWriter, q *http.Request) {
path := q.URL.Path
if path == "/hello" {
r.mux[path].ServeHTTP(w, q)
} else {
w.Write([]byte("zzh not find"))
}
}
// time middle
func timeMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request){
timeStart := time.Now().UnixNano() / 1e6
next.ServeHTTP(w, r)
timeEnd := time.Now().UnixNano() / 1e6
timeElapsed := timeEnd - timeStart
fmt.Println("处理时间:", timeElapsed)
})
}
func pathMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Println("before pathMiddleware")
fmt.Println(r.URL.Path)
next.ServeHTTP(w, r)
fmt.Println("after pathMiddleware")
})
}
func hello(w http.ResponseWriter, r *http.Request) {
fmt.Println("this is hello function")
_, err := w.Write([]byte("hello zzh"))
if err != nil {
fmt.Println(err)
}
}
func main(){
r := NewRouter()
r.Use(timeMiddleware)
r.Use(pathMiddleware)
r.Add("/hello", http.HandlerFunc(hello))
//http.HandleFunc("/hello", hello)
http.ListenAndServe(":12345", r)
}