golang simply gets the implementation code to upload the file size

This example shows how golang can simply get the size of an uploaded file. I will share it with you for your reference as follows:

package main

import (

    "fmt"

    "io"

    "net/http"

    "log"

    "os"

)

//  Gets the interface for the file size 

type Size interface {

    Size() int64

}

//  Interface to get file information 

type Stat interface {

    Stat() (os.FileInfo, error)

}

// hello world, the web server

func HelloServer(w http.ResponseWriter, r *http.Request) {

    if "POST" == r.Method {

        file, _, err := r.FormFile("userfile")

        if err != nil {

            http.Error(w, err.Error(), 500)

            return

        }

        if statInterface, ok := file.(Stat); ok {

            fileInfo, _ := statInterface.Stat()

            fmt.Fprintf(w, " The size of the uploaded file is : %d", fileInfo.Size())

        }

        if sizeInterface, ok := file.(Size); ok {

            fmt.Fprintf(w, " The size of the uploaded file is : %d", sizeInterface.Size())

        }

        return

    }

    //  The upload page 

    w.Header().Add("Content-Type", "text/html")

    w.WriteHeader(200)

    html := `

<form enctype="multipart/form-data" action="/hello" method="POST">

    Send this file: <input name="userfile" type="file" />

    <input type="submit" value="Send File" />

</form>

`

    io.WriteString(w, html)

}

func main() {

    http.HandleFunc("/hello", HelloServer)

    err := http.ListenAndServe(":12345", nil)

    if err != nil {

        log.Fatal("ListenAndServe: ", err)

    }

}

I hope this article has been helpful to you in programming Go.