Go Tips & Common Mistakes

Go HTTP file upload and download

This code implements a simple Go language HTTP service, which not only includes file upload and download functions, but also controls file size and generates new file names, etc.

• uploadPath: Defines the storage path of the uploaded file.
• maxUploadSize: Defines the maximum file size allowed to upload to 10MB.

package mainimport (
 "fmt"
 "io"
 "math/rand"
 "net"
 "net/http"
 "os"
 "path"
 "path/filepath"
)const (
 uploadPath    = "tmp"
 maxUploadSize = 10 << 20 //10MB
)func main() {
 listen, _ := net.Listen("tcp", ":8888") //文件上传
 http.HandleFunc("/upload", func(w http.ResponseWriter, r *http.Request) {
  if err := r.ParseMultipartForm(maxUploadSize); err != nil {
   fmt.Printf("ParseMultipartForm err = %s", err)
   return
  }  file, fileHeader, err := r.FormFile("file")
  if err != nil {
   fmt.Printf("FormFile err = %s", err)
   return
  }  defer func() {
   _ = file.Close()
  }()  if fileHeader.Size > maxUploadSize {
   fmt.Printf("max err = %s", err)
   return
  }  fileBytes, err := io.ReadAll(file)
  if err != nil {
   fmt.Printf("read err = %s", err)
   return
  }  newFileName := randToken(12) + path.Ext(fileHeader.Filename) //新文件名+后缀
  newFile, err := os.Create(filepath.Join(uploadPath, newFileName))
  if err != nil {
   fmt.Printf("Create err = %s", err)
   return
  }  defer func() {
   _ = newFile.Close()
  }()  if _, err := newFile.Write(fileBytes); err != nil || newFile.Close() != nil {
   fmt.Printf("Write err = %s", err)…