Golang How HTTP client uploads and how server receives files

Given an example, use Mime/multipart to implement how the client uploads a file to the server, and then how the server accepts the file.

See Server.go Code

package mainimport (    "io"    "os"    "fmt"    "io/ioutil"    "net/http")func uploadHandler(w http.ResponseWriter, r *http.Request) {    reader, err := r.MultipartReader()    if err != nil {        http.Error(w, err.Error(), http.StatusInternalServerError)        return    }    for {        part, err := reader.NextPart()        if err == io.EOF {            break        }        fmt.Printf("FileName=[%s], FormName=[%s]\n", part.FileName(), part.FormName())        if part.FileName() == "" {  // this is FormData            data, _ := ioutil.ReadAll(part)            fmt.Printf("FormData=[%s]\n", string(data))        } else {    // This is FileData            dst, _ := os.Create("./" + part.FileName() + ".upload")            defer dst.Close()            io.Copy(dst, part)        }    }}func main() {    http.HandleFunc("/upload", uploadHandler)    http.ListenAndServe(":8080", nil)}

Example 1:client uploading a file

package mainimport (    "io"    "os"    "log"    "bytes"    "io/ioutil"    "net/http"    "mime/multipart")func main() {    bodyBuffer := &bytes.Buffer{}    bodyWriter := multipart.NewWriter(bodyBuffer)    fileWriter, _ := bodyWriter.CreateFormFile("files", "file.txt")    file, _ := os.Open("file.txt")    defer file.Close()    io.Copy(fileWriter, file)    contentType := bodyWriter.FormDataContentType()    bodyWriter.Close()    resp, _ := http.Post("http://localhost:8080/upload", contentType, bodyBuffer)    defer resp.Body.Close()    resp_body, _ := ioutil.ReadAll(resp.Body)    log.Println(resp.Status)    log.Println(string(resp_body))}

Example 2:client uploading multiple files

package mainimport (    "io"    "os"    "log"    "bytes"    "io/ioutil"    "net/http"    "mime/multipart")func main() {    bodyBuffer := &bytes.Buffer{}    bodyWriter := multipart.NewWriter(bodyBuffer)    // file1    fileWriter1, _ := bodyWriter.CreateFormFile("files", "file1.txt")    file1, _ := os.Open("file1.txt")    defer file1.Close()    io.Copy(fileWriter1, file1)    // file2    fileWriter2, _ := bodyWriter.CreateFormFile("files", "file2.txt")    file2, _ := os.Open("file2.txt")    defer file2.Close()    io.Copy(fileWriter2, file2)    contentType := bodyWriter.FormDataContentType()    bodyWriter.Close()    resp, _ := http.Post("http://localhost:8080/upload", contentType, bodyBuffer)    defer resp.Body.Close()    resp_body, _ := ioutil.ReadAll(resp.Body)    log.Println(resp.Status)    log.Println(string(resp_body))}

Example 3: Uploading other form data

Package Mainimport ("IO" "OS" "Log" "bytes" "Io/ioutil" "Net/http" "Mime/multipart") func main () { Bodybuffer: = &bytes. buffer{} bodywriter: = multipart. Newwriter (Bodybuffer)//File1 FileWriter1, _: = Bodywriter.createformfile ("Files", "File1.txt") file1, _: = OS.O Pen ("file1.txt") defer file1. Close () Io. Copy (FileWriter1, file1)//File2 FileWriter2, _: = Bodywriter.createformfile ("Files", "File2.txt") file2, _: = O S.open ("File2.txt") defer file2. Close () Io.        Copy (FileWriter2, file2)//Other form data extraparams: = map[string]string{"title": "My Document",    "Author": "Matt Aimonetti", "description": "A document with all the Go programming language Secrets", } for key, value: = Range Extraparams {_ = Bodywriter.writefield (key, Value)} ContentType: = Bodywriter . Formdatacontenttype () Bodywriter.close () resp, _: = http. Post ("Http://localhost:8080/upload", ContenttypE, Bodybuffer) defer resp. Body.close () Resp_body, _: = Ioutil. ReadAll (resp. Body) log. Println (resp. Status) log. Println (String (resp_body))}

Look at the server side of the run output:

$ go build server.go && ./serverFileName=[file1.txt], FormName=[files]FileName=[file2.txt], FormName=[files]FileName=[], FormName=[description]FormData=[A document with all the Go programming language secrets]FileName=[], FormName=[title]FormData=[My Document]FileName=[], FormName=[author]FormData=[Matt Aimonetti]$ ls -ltotal 25180-rwxr-xr-x 1 ... 6179399 Jun 22 08:07 client-rw-r--r-- 1 ...    1952 Jun 22 08:06 client.go-rw-r--r-- 1 ...      15 Jun 22 07:11 file1.txt-rw-r--r-- 1 ...      15 Jun 22 08:28 file1.txt.upload-rw-r--r-- 1 ...      14 Jun 22 07:11 file2.txt-rw-r--r-- 1 ...      14 Jun 22 08:28 file2.txt.upload-rw-r--r-- 1 ...      15 Jun 22 07:56 file.txt-rw-r--r-- 1 ...      15 Jun 22 08:10 file.txt.upload-rwxr-xr-x 1 ... 6717437 Jun 22 07:59 server-rw-r--r-- 1 ...    1580 Jun 22 07:58 server.go