Go Upload and download files

Go comes with many packages. This example uses THE IO package and NET package apis to simply upload and download files based on HTTP (demo only).

Define file store file

// Assuming file upload is local server, base path of upload
const BaseUploadPath = "/var/file"
Copy the code

The main function listens for HTTP services

func main(a) {
	http.HandleFunc("/upload", handleUpload)
	http.HandleFunc("/download", handleDownload)

	err := http.ListenAndServe(": 3000".nil)
	iferr ! =nil  {
		log.Fatal("Server run fail")}}Copy the code

File upload processor

func handleUpload (w http.ResponseWriter, request *http.Request)  {
	// Only POST method is allowed for file upload
	ifrequest.Method ! = http.MethodPost { w.WriteHeader(http.StatusMethodNotAllowed) _, _ = w.Write([]byte("Method not allowed"))
		return
	}

	// Read the file from the form
	file, fileHeader, err := request.FormFile("file")
	iferr ! =nil {
		_, _ = io.WriteString(w, "Read file error")
		return
	}
	//defer closes the file at the end
	defer file.Close()
	log.Println("filename: " + fileHeader.Filename)

	// Create a file
	newFile, err := os.Create(BaseUploadPath + "/" + fileHeader.Filename)
	iferr ! =nil {
		_, _ = io.WriteString(w, "Create file error")
		return
	}
	//defer closes the file at the end
	defer newFile.Close()

	// Write the file locally
	_, err = io.Copy(newFile, file)
	iferr ! =nil {
		_, _ = io.WriteString(w, "Write file error")
		return
	}
	_,_ = io.WriteString(w, "Upload success")}Copy the code

File download processor

func handleDownload (w http.ResponseWriter, request *http.Request) {
	// Only GET method is allowed for file upload
	ifrequest.Method ! = http.MethodGet { w.WriteHeader(http.StatusMethodNotAllowed) _, _ = w.Write([]byte("Method not allowed"))
		return
	}
	/ / file name
	filename := request.FormValue("filename")
	if filename == "" {
		w.WriteHeader(http.StatusBadRequest)
		_, _ = io.WriteString(w, "Bad request")
		return
	}
	log.Println("filename: " + filename)
	// Open the file
	file, err := os.Open(BaseUploadPath + "/" + filename)
	iferr ! =nil {
		w.WriteHeader(http.StatusBadRequest)
		_, _ = io.WriteString(w, "Bad request")
		return
	}
	// Close the file
	defer file.Close()

	// Set the header for the response
	w.Header().Add("Content-type"."application/octet-stream")
	w.Header().Add("content-disposition"."attachment; filename=\""+filename+"\" ")
	// Write the file to responseBody
	_, err = io.Copy(w, file)
	iferr ! =nil {
		w.WriteHeader(http.StatusBadRequest)
		_, _ = io.WriteString(w, "Bad request")
		return}}Copy the code

Resources: golang.org/pkg/