如何传输文件流给前端

通过链接下载图片，直接http请求然后将文件流返回
注：music.ly是一个下载tiktok视频的免费接口 https://api19-core-c-useast1a.musical.ly/aweme/v1/feed/?aweme_id=xxx

func (m *FileBiz) DownloadFileV2(ctx *ctrl.Context, fileLink, fileName string) (err error) {

	// 记录下载日志
	record.BusinessLog(record.Debug, "RecordDownloadFileV2", fmt.Sprintf("filePath:%s,wsId:%s,email:%s", fileLink, ctx.GetString("ws_id"), ctx.GetString("email")), "")

	// 获取地址异常
	if fileLink == "" {
		err = errInfo.ErrFilesNull
		return
	}

	// 初始化
	request, err := http.NewRequest("GET", fileLink, nil)
	if err != nil {
		record.BusinessLog(record.Error, "NewRequest", fmt.Sprintf("filePath:%s", fileLink), err.Error())
		err = errInfo.ErrHttpInit
		return
	}

	// 执行请求
	clt := http.Client{}
	resp, err := clt.Do(request)
	if err != nil {
		record.BusinessLog(record.Error, "HttpDp", fmt.Sprintf("filePath:%s", fileLink), err.Error())
		err = errInfo.ErrHttpDo
		return
	}

	defer func(Body io.ReadCloser) {
		errClose := Body.Close()
		if errClose != nil {
			record.BusinessLog(record.Error, "FileClose", fmt.Sprintf("filePath:%s", fileLink), errClose.Error())
		}
	}(resp.Body)

	// 响应头
	ctx.Header("Content-Length", resp.Header.Get("Content-Length"))
	ctx.Header("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", fileName))
	ctx.Header("Content-Type", "application/octet-stream;charset=UTF-8")
	ctx.Header("Set-Cookie", "download=success; Domain=.media.io; Path=/;")

	// 响应流
	written, err := io.Copy(ctx.ResponseWriter(), resp.Body)
	if err != nil {
		record.BusinessLog(record.Error, "IoCopy", fmt.Sprintf("filePath:%s, written:%d", fileLink, written), err.Error())
		err = errInfo.ErrResponseWritten
	}

	return
}