http函数Golang的附加参数

Question

I am trying to pass string to handler in given example.

package main
import (
"fmt"
"net/http"
)

func handler(w http.ResponseWriter, r *http.Request) {
     fmt.Fprintf(w, "Hi there, I love %s!", r.URL.Path[1:])
}

func main() {
     http.HandleFunc("/", handler)
     http.ListenAndServe(":8080", nil)
}

Here is what i tried but it throws an error as it expects regular number of arguments:

package main
import (
"fmt"
"net/http"
)

func handler(w http.ResponseWriter, r *http.Request, s *string) {
     fmt.Fprintf(w, "Hi there, I love %s!", *s)
}

func main() {
     files := "bar"
     http.HandleFunc("/", handler(&files))
     http.ListenAndServe(":8080", nil)
}

Answer 1

I'm a little unclear on what you're trying to do, but based off what you said, why not try to encapsulate the data you want to pass in like this:

package main
import (
    "fmt"
    "net/http"
)

type FilesHandler struct {
    Files string
}

func (fh *FilesHandler) handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hi there, I love %s!", fh.Files)
}

func main() {
    myFilesHandler := &FilesHandler{Files: "bar"}
    http.HandleFunc("/", myFilesHandler.handler)
    http.ListenAndServe(":8080", nil)
}

This provides a little more granular control of what you make available to your Handler.