go通过http发送form-data

首先是获取form-data内容

func ResendFormFile(r *http.Request, URL string) {
	data := r.FormValue("data")
	formFile, fileHeader, err := r.FormFile("pic")
	if err != nil {
		return
	}
	_, status := RequestPost(formFile, fileHeader.Filename, []byte(data), URL)
	if (status / 100) != 2 {
		fmt.Println("转发图片失败")
	}
	return
}

然后是发送

func RequestPost(formFile multipart.File, filename string, data []byte, postURL string) (resp interface{}, status int) {
	buf := new(bytes.Buffer)
	w := multipart.NewWriter(buf)
	if fw, err := w.CreateFormField("data"); err == nil {
		fw.Write(data)
	}
	if createFormFile, err := w.CreateFormFile("pic", filename); err == nil {
		readAll, _ := ioutil.ReadAll(formFile)
		createFormFile.Write(readAll)
	}
	w.Close()
	req, err := http.NewRequest(http.MethodPost, postURL, buf)
	if err != nil {
		return
	}
	// Don't forget to set the content type, this will contain the boundary.
	req.Header.Set("Content-Type", w.FormDataContentType())
	client := &http.Client{}
	res, err := client.Do(req)
	if err != nil {
		return
	}
	return res.Body, res.StatusCode
}

这样返回的body是不可以直接json序列化的
可以先使用ioutil读出来或者byte.Buffer进行中转都是比较简单的选择

func UnmarshalWriter(body io.ReadCloser, w http.ResponseWriter) {
	all, _ := ioutil.ReadAll(body)
	buffer := bytes.NewBuffer(all)
	buffer.WriteTo(w)
}

基本操作就这么多，欢迎提问！