为每个请求执行中间件，无需指定挂载路径

Question

Node.js Express 可以插入一个没有挂载路径的中间件，它会针对每个请求执行。有没有办法在 GO 中做到这一点？var app = express();// a middleware with no mount path; gets executed for every request to the appapp.use(function (req, res, next) {  console.log('Time:', Date.now());  next();});

Answer 1

这是 Go 的一个基本示例net/http：

func main() {

   r := http.NewServeMux()

   r.HandleFunc("/some-route", SomeHandler)

   // Wrap your *ServeMux with a function that looks like

   // func SomeMiddleware(h http.Handler) http.Handler   

   http.ListenAndServe("/", YourMiddleware(r))

}

中间件可能是这样的：

func YourMiddleware(h http.Handler) http.Handler {

   fn := func(w http.ResponseWriter, r *http.Request) {

       // Do something with the response

       w.Header().Set("Server", "Probably Go")

       // Call the next handler

       h.ServeHTTP(w, r)

   }

   // Type-convert our function so that it

   // satisfies the http.Handler interface

   return http.HandlerFunc(fn)

}

如果您有很多要链接的中间件，像alice这样的包可以简化它，这样您就不会Wrapping(AllOf(YourMiddleware(r))))那样了。您也可以编写自己的助手 -

func use(h http.Handler, middleware ...func(http.Handler) http.Handler) http.Handler {

    for _, m := range middleware {

        h = m(h)

    }

    return h

}

// Example usage:

defaultRouter := use(r, handlers.LoggingHandler, csrf.Protect(key), CORSMiddleware)

http.ListenAndServe(":8000", defaultRouter)