Golang使用原生http实现中间件的代码详解
投稿：bairu
中间件（middleware）：常被用来做认证校验、审计等,家常用的Iris、Gin等web框架,都包含了中间件逻辑,但有时我们引入该框架显得较为繁重,本文将介绍通过golang原生http来实现中间件操作,需要的朋友可以参考下
Golang原生http实现中间件
中间件（middleware）：常被用来做认证校验、审计等
大家常用的Iris、Gin等web框架，都包含了中间件逻辑。但有时我们引入该框架显得较为繁重，本文将介绍通过golang原生http来实现中间件操作。全部代码：https://github.com/ziyifast/ziyifast-code_instruction/tree/main/middleware
1 定义http.Handler：具体中间件操作
①CORSMiddleware：允许跨域
// CORSMiddleware handles Cross-Origin Resource Sharing (CORS) responses.
func CORSMiddleware(next http.Handler) http.Handler {
fmt.Println("cors middleware....")
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.Method == "OPTIONS" {
w.Header().Set("Access-Control-Allow-Origin", "*")
w.Header().Set("Access-Control-Allow-Methods", "GET, POST, OPTIONS, DELETE")
//如果前后端需要传递自定义请求头，需要再Access-Control-Allow-Headers中匹配(Yi-Auth-Token)
w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Accept, Yi-Auth-Token")
w.WriteHeader(http.StatusOK)
return
}
w.Header().Set("Access-Control-Allow-Origin", "*")
w.Header().Set("Access-Control-Allow-Methods", "GET, POST, OPTIONS, DELETE")
w.Header().Set("Access-Control-Allow-Headers", "Content-Type,Accept,Yi-Auth-Token")
//交给下一个中间件处理
next.ServeHTTP(w, r)
})
}
②AuthMiddleware：认证
// AuthMiddleware simulates a simple authentication middleware.
func AuthMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Println("auth middleware...")
//store info in ctx
token := r.Header.Get("Token")
if len(token) != 0 {
//TODO 1. check token 2. get userinfo from token
userID := "1"
ctx := context.WithValue(r.Context(), "userID", userID)
r = r.WithContext(ctx)
}
next.ServeHTTP(w, r)
})
}
③AuditMiddleware：审计操作
// AuditMiddleware simulates an audit logging middleware.
func AuditMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Println("audit middleware...")
next.ServeHTTP(w, r)
})
}
④SmokeHandler：具体处理操作
// SmokeHandler returns the current time as a string.
func SmokeHandler(w http.ResponseWriter, r *http.Request) {
fmt.Println("smoke handle....")
_, err := w.Write([]byte(time.Now().String()))
if err != nil {
http.Error(w, "Internal Server Error", http.StatusInternalServerError)
}
}
2 义中间件类型&定义中间件链
①type Middleware func(http.Handler) http.Handler：定义中间件
type Middleware func(http.Handler) http.Handler
②定义中间件链MiddlewareChain
// NewMiddlewareChain creates a new middleware chain with the given middlewares.
func NewMiddlewareChain(middlewares ...Middleware) Middleware {
return func(handler http.Handler) http.Handler {
for i := len(middlewares) - 1; i >= 0; i-- {
handler = middlewares[i](handler)
}
return handler
}
}
3 启动http服务
func RunAndServe() error {
defer func() {
if e := recover(); e != nil {
fmt.Println("err=", e)
}
}()
mux := http.NewServeMux()
// Create middleware chains for routes.
authMiddlewareChain := NewMiddlewareChain(CORSMiddleware, AuthMiddleware, AuditMiddleware)
//noAuthMiddlewareChain := NewMiddlewareChain(CORSMiddleware)
// Convert the middleware chain result to http.HandlerFunc.
smokeHandlerWrapped := func(w http.ResponseWriter, r *http.Request) {
authMiddlewareChain(http.HandlerFunc(SmokeHandler)).ServeHTTP(w, r)
}
mux.HandleFunc("/smoke", smokeHandlerWrapped)
fmt.Printf("listening on http://localhost:%d\n", 9999)
return http.ListenAndServe(":9999", mux)
}
4 测试
启动后端
go run main.go
2. 浏览器访问http://localhost:9999/smoke
3. 后端日志打印
可以看到是最后才处理我们的业务Handler
全部代码
package main
import (
"context"
"fmt"
"net/http"
"time"
)
type Middleware func(http.Handler) http.Handler
// CORSMiddleware handles Cross-Origin Resource Sharing (CORS) responses.
func CORSMiddleware(next http.Handler) http.Handler {
fmt.Println("cors middleware....")
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.Method == "OPTIONS" {
w.Header().Set("Access-Control-Allow-Origin", "*")
w.Header().Set("Access-Control-Allow-Methods", "GET, POST, OPTIONS, DELETE")
//如果前后端需要传递自定义请求头，需要再Access-Control-Allow-Headers中匹配(Yi-Auth-Token)
w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Accept, Yi-Auth-Token")
w.WriteHeader(http.StatusOK)
return
}
w.Header().Set("Access-Control-Allow-Origin", "*")
w.Header().Set("Access-Control-Allow-Methods", "GET, POST, OPTIONS, DELETE")
w.Header().Set("Access-Control-Allow-Headers", "Content-Type,Accept,Yi-Auth-Token")
next.ServeHTTP(w, r)
})
}
// AuthMiddleware simulates a simple authentication middleware.
func AuthMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Println("auth middleware...")
//store info in ctx
token := r.Header.Get("Token")
if len(token) != 0 {
//TODO 1. check token 2. get userinfo from token
userID := "1"
ctx := context.WithValue(r.Context(), "userID", userID)
r = r.WithContext(ctx)
}
next.ServeHTTP(w, r)
})
}
// AuditMiddleware simulates an audit logging middleware.
func AuditMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
fmt.Println("audit middleware...")
next.ServeHTTP(w, r)
})
}
// SmokeHandler returns the current time as a string.
func SmokeHandler(w http.ResponseWriter, r *http.Request) {
fmt.Println("smoke handle....")
_, err := w.Write([]byte(time.Now().String()))
if err != nil {
http.Error(w, "Internal Server Error", http.StatusInternalServerError)
}
}
// NewMiddlewareChain creates a new middleware chain with the given middlewares.
func NewMiddlewareChain(middlewares ...Middleware) Middleware {
return func(handler http.Handler) http.Handler {
for i := len(middlewares) - 1; i >= 0; i-- {
handler = middlewares[i](handler)
}
return handler
}
}
func RunAndServe() error {
defer func() {
if e := recover(); e != nil {
fmt.Println("err=", e)
}
}()
mux := http.NewServeMux()
// Create middleware chains for routes.
authMiddlewareChain := NewMiddlewareChain(CORSMiddleware, AuthMiddleware, AuditMiddleware)
//noAuthMiddlewareChain := NewMiddlewareChain(CORSMiddleware)
// Convert the middleware chain result to http.HandlerFunc.
smokeHandlerWrapped := func(w http.ResponseWriter, r *http.Request) {
authMiddlewareChain(http.HandlerFunc(SmokeHandler)).ServeHTTP(w, r)
}
mux.HandleFunc("/smoke", smokeHandlerWrapped)
fmt.Printf("listening on http://localhost:%d\n", 9999)
return http.ListenAndServe(":9999", mux)
}
func main() {
RunAndServe()
}
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