中间件模式
函数式中间件、链式组合、日志/认证/CORS 中间件实战
中间件模式
Go 的中间件是典型的函数式装饰器模式——包装 http.Handler，在请求前后添加逻辑。
学完本章你将： 掌握函数式中间件、链式组合、日志/认证/CORS 实战。
认证中间件
go
func authMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
token := r.Header.Get("Authorization")
if token == "" {
http.Error(w, "未授权", http.StatusUnauthorized)
return
}
// 验证 token...
next.ServeHTTP(w, r)
})
}CORS 中间件
go
func corsMiddleware(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Access-Control-Allow-Origin", "*")
w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE")
if r.Method == "OPTIONS" {
w.WriteHeader(http.StatusNoContent)
return
}
next.ServeHTTP(w, r)
})
}超时中间件
go
func timeoutMiddleware(timeout time.Duration) Middleware {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
ctx, cancel := context.WithTimeout(r.Context(), timeout)
defer cancel()
next.ServeHTTP(w, r.WithContext(ctx))
})
}
}