middleware

// basic-middleware.go
package main
import (
    "fmt"
    "log"
    "net/http"
)
func logging(f http.HandlerFunc) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        log.Println(r.URL.Path)
        f(w, r)
    }
}
func foo(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintln(w, "foo")
}
func bar(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintln(w, "bar")
}
func main() {
    http.HandleFunc("/foo", logging(foo))
    http.HandleFunc("/bar", logging(bar))
    http.ListenAndServe(":8080", nil)
}

参考

https://gowebexamples.com/basic-middleware/
https://chai2010.cn/advanced-go-programming-book/ch5-web/ch5-03-middleware.html
https://colobu.com/2019/08/21/decorator-pattern-pipeline-pattern-and-go-web-middlewares/