我正在尝试使用go将图像从我的计算机上传到网站。通常,我使用bash脚本将文件和密钥发送到服务器:
curl -F "image"=@"IMAGEFILE" -F "key"="KEY" URL
它工作正常,但我正在尝试将此请求转换为我的golang程序。
http://matt.aimonetti.net/posts/2013/07/01/golang-multipart-file-upload-example/
我尝试了这个链接和许多其他链接,但是,对于我尝试的每个代码,来自服务器的响应是“没有图像发送”,我不知道为什么。如果有人知道上面的例子发生了什么。
答案 0 :(得分:99)
以下是一些示例代码。
简而言之,您需要使用mime/multipart
package来构建表单。
package main
import (
"bytes"
"fmt"
"io"
"mime/multipart"
"net/http"
"net/http/httptest"
"net/http/httputil"
"os"
"strings"
)
func main() {
var client *http.Client
var remoteURL string
{
//setup a mocked http client.
ts := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
b, err := httputil.DumpRequest(r, true)
if err != nil {
panic(err)
}
fmt.Printf("%s", b)
}))
defer ts.Close()
client = ts.Client()
remoteURL = ts.URL
}
//prepare the reader instances to encode
values := map[string]io.Reader{
"file": mustOpen("main.go"), // lets assume its this file
"other": strings.NewReader("hello world!"),
}
err := Upload(client, remoteURL, values)
if err != nil {
panic(err)
}
}
func Upload(client *http.Client, url string, values map[string]io.Reader) (err error) {
// Prepare a form that you will submit to that URL.
var b bytes.Buffer
w := multipart.NewWriter(&b)
for key, r := range values {
var fw io.Writer
if x, ok := r.(io.Closer); ok {
defer x.Close()
}
// Add an image file
if x, ok := r.(*os.File); ok {
if fw, err = w.CreateFormFile(key, x.Name()); err != nil {
return
}
} else {
// Add other fields
if fw, err = w.CreateFormField(key); err != nil {
return
}
}
if _, err = io.Copy(fw, r); err != nil {
return err
}
}
// Don't forget to close the multipart writer.
// If you don't close it, your request will be missing the terminating boundary.
w.Close()
// Now that you have a form, you can submit it to your handler.
req, err := http.NewRequest("POST", url, &b)
if err != nil {
return
}
// Don't forget to set the content type, this will contain the boundary.
req.Header.Set("Content-Type", w.FormDataContentType())
// Submit the request
res, err := client.Do(req)
if err != nil {
return
}
// Check the response
if res.StatusCode != http.StatusOK {
err = fmt.Errorf("bad status: %s", res.Status)
}
return
}
func mustOpen(f string) *os.File {
r, err := os.Open(f)
if err != nil {
panic(err)
}
return r
}
答案 1 :(得分:1)
这是我使用过的函数,它使用io.Pipe()
来避免将整个文件读入内存或需要管理任何缓冲区。它仅处理单个文件,但可以通过在goroutine中添加更多部分来轻松扩展以处理更多文件。幸福的道路行之有效。错误路径没有太多测试。
import (
"fmt"
"io"
"mime/multipart"
"net/http"
"os"
)
func UploadMultipartFile(client *http.Client, uri, key, path string) (*http.Response, error) {
body, writer := io.Pipe()
req, err := http.NewRequest(http.MethodPost, uri, body)
if err != nil {
return nil, err
}
mwriter := multipart.NewWriter(writer)
req.Header.Add("Content-Type", mwriter.FormDataContentType())
errchan := make(chan error)
go func() {
defer close(errchan)
defer writer.Close()
defer mwriter.Close()
w, err := mwriter.CreateFormFile(key, path)
if err != nil {
errchan <- err
return
}
in, err := os.Open(path)
if err != nil {
errchan <- err
return
}
defer in.Close()
if written, err := io.Copy(w, in); err != nil {
errchan <- fmt.Errorf("error copying %s (%d bytes written): %v", path, written, err)
return
}
if err := mwriter.Close(); err != nil {
errchan <- err
return
}
}()
resp, err := client.Do(req)
merr := <-errchan
if err != nil || merr != nil {
return resp, fmt.Errorf("http error: %v, multipart error: %v", err, merr)
}
return resp, nil
}
答案 2 :(得分:1)
将文件从一项服务发送到另一项服务:
func UploadFile(network, uri string, f multipart.File, h *multipart.FileHeader) error {
buf := new(bytes.Buffer)
writer := multipart.NewWriter(buf)
part, err := writer.CreateFormFile("file", h.Filename)
if err != nil {
log.Println(err)
return err
}
b, err := ioutil.ReadAll(f)
if err != nil {
log.Println(err)
return err
}
part.Write(b)
writer.Close()
req, _ := http.NewRequest("POST", uri, buf)
req.Header.Add("Content-Type", writer.FormDataContentType())
client := &http.Client{}
resp, err := client.Do(req)
if err != nil {
return err
}
defer resp.Body.Close()
b, _ = ioutil.ReadAll(resp.Body)
if resp.StatusCode >= 400 {
return errors.New(string(b))
}
return nil
}
答案 3 :(得分:0)
关于attila -o的帖子,请求标题没有边界,因为Writer已经关闭。
// after the close, the bounday will be nil.
w.Close()
...
req.Header.Set("Content-Type", w.FormDataContentType())
所以,我认为它应该在集合之后关闭。
req.Header.Set("Content-Type", w.FormDataContentType())
w.Close()
答案 4 :(得分:0)
我发现this tutorial非常有助于澄清我对Go中文件上传的疑惑。
基本上,您在客户端使用myArray
通过ajax上传文件,并在服务器上使用以下一小段Go代码:
form-data
此处file, handler, err := r.FormFile("img") // img is the key of the form-data
if err != nil {
fmt.Println(err)
return
}
defer file.Close()
fmt.Println("File is good")
fmt.Println(handler.Filename)
fmt.Println()
fmt.Println(handler.Header)
f, err := os.OpenFile(handler.Filename, os.O_WRONLY|os.O_CREATE, 0666)
if err != nil {
fmt.Println(err)
return
}
defer f.Close()
io.Copy(f, file)
为r
。 P.S。这只会将文件存储在同一文件夹中,并且不会执行任何安全检查。
答案 5 :(得分:0)
也许这可能很有用https://github.com/030/go-curl
./go-curl -url \ http://localhost:9999/service/rest/v1/components?repository=maven-releases \ -user admin -pass admin123 -F \ "maven2.asset1=@utils/test-files-multipart/file1.pom,\ maven2.asset1.extension=pom,\ maven2.asset2=@utils/test-files-multipart/file1.jar,\ maven2.asset2.extension=jar,\ maven2.asset3=@utils/test-files-multipart/file1-sources.jar,\ maven2.asset3.extension=sources.jar"
答案 6 :(得分:0)
在对这个问题的可接受答案进行解码以用于单元测试之后,我最终得到了以下重构代码:
func createMultipartFormData(t *testing.T, fieldName, fileName string) (bytes.Buffer, *multipart.Writer) {
var b bytes.Buffer
var err error
w := multipart.NewWriter(&b)
var fw io.Writer
file := mustOpen(fileName)
if fw, err = w.CreateFormFile(fieldName, file.Name()); err != nil {
t.Errorf("Error creating writer: %v", err)
}
if _, err = io.Copy(fw, file); err != nil {
t.Errorf("Error with io.Copy: %v", err)
}
w.Close()
return b, w
}
func mustOpen(f string) *os.File {
r, err := os.Open(f)
if err != nil {
pwd, _ := os.Getwd()
fmt.Println("PWD: ", pwd)
panic(err)
}
return r
}
现在它应该很容易使用:
b, w := createMultipartFormData(t, "image","../luke.png")
req, err := http.NewRequest("POST", url, &b)
if err != nil {
return
}
// Don't forget to set the content type, this will contain the boundary.
req.Header.Set("Content-Type", w.FormDataContentType())
答案 7 :(得分:0)
要扩展@ attila-o答案,这是我在Go with中执行POST HTTP请求所用的代码:
卷毛表示:
curl -X POST \
http://localhost:9091/storage/add \
-H 'content-type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW' \
-F owner=0xc916Cfe5c83dD4FC3c3B0Bf2ec2d4e401782875e \
-F password=$PWD \
-F file=@./internal/file_example_JPG_500kB.jpg
前进:
client := &http.Client{
Timeout: time.Second * 10,
}
req, err := createStoragePostReq(cfg)
res, err := executeStoragePostReq(client, req)
func createStoragePostReq(cfg Config) (*http.Request, error) {
extraFields := map[string]string{
"owner": "0xc916cfe5c83dd4fc3c3b0bf2ec2d4e401782875e",
"password": "pwd",
}
url := fmt.Sprintf("http://localhost:%d%s", cfg.HttpServerConfig().Port(), lethstorage.AddRoute)
b, w, err := createMultipartFormData("file","./internal/file_example_JPG_500kB.jpg", "file_example_JPG_500kB.jpg", extraFields)
if err != nil {
return nil, err
}
req, err := http.NewRequest("POST", url, &b)
if err != nil {
return nil, err
}
req.Header.Set("Content-Type", w.FormDataContentType())
return req, nil
}
func executeStoragePostReq(client *http.Client, req *http.Request) (lethstorage.AddRes, error) {
var addRes lethstorage.AddRes
res, err := client.Do(req)
if err != nil {
return addRes, err
}
defer res.Body.Close()
data, err := ioutil.ReadAll(res.Body)
if err != nil {
return addRes, err
}
err = json.Unmarshal(data, &addRes)
if err != nil {
return addRes, err
}
return addRes, nil
}
func createMultipartFormData(fileFieldName, filePath string, fileName string, extraFormFields map[string]string) (b bytes.Buffer, w *multipart.Writer, err error) {
w = multipart.NewWriter(&b)
var fw io.Writer
file, err := os.Open(filePath)
if fw, err = w.CreateFormFile(fileFieldName, fileName); err != nil {
return
}
if _, err = io.Copy(fw, file); err != nil {
return
}
for k, v := range extraFormFields {
w.WriteField(k, v)
}
w.Close()
return
}
答案 8 :(得分:0)
在单元测试中也有同样的问题,如果您只需要发送数据以验证该帖子(以下)对我来说简单一点。希望它可以帮助节省一些时间。
fileReader := strings.NewReader("log file contents go here")
b := bytes.Buffer{} // buffer to write the request payload into
fw := multipart.NewWriter(&b)
fFile, _ := fw.CreateFormFile("file", "./logfile.log")
io.Copy(fFile, fileReader)
fw.Close()
req, _ := http.NewRequest(http.MethodPost, url, &b)
req.Header.Set("Content-Type", fw.FormDataContentType())
resp, err := http.DefaultClient.Do(req)
assert.NoError(t, err)
assert.Equal(t, http.StatusOK, resp.StatusCode)
对我来说,fileReader只是一个字符串读取器,因为我正在发布一个日志文件。如果是图片,则应发送适当的阅读器。
答案 9 :(得分:0)
这是一个适用于文件或字符串的选项:
package main
import (
"bytes"
"io"
"mime/multipart"
"os"
"strings"
)
func createForm(form map[string]string) (string, io.Reader, error) {
body := new(bytes.Buffer)
mp := multipart.NewWriter(body)
defer mp.Close()
for key, val := range form {
if strings.HasPrefix(val, "@") {
val = val[1:]
file, err := os.Open(val)
if err != nil { return "", nil, err }
defer file.Close()
part, err := mp.CreateFormFile(key, val)
if err != nil { return "", nil, err }
io.Copy(part, file)
} else {
mp.WriteField(key, val)
}
}
return mp.FormDataContentType(), body, nil
}
示例:
package main
import "net/http"
func main() {
form := map[string]string{"image": "@IMAGEFILE", "key": "KEY"}
ct, body, err := createForm(form)
if err != nil {
panic(err)
}
http.Post("https://stackoverflow.com", ct, body)
}