请教一下golang通过http.Get怎么获得文件大小？

	resp, err := http.Get(url)
	if err != nil {
		log.Fatalf("HEAD failed: %v", err)
	}
	fmt.Printf("resp: %s\n", resp.Status)
	fmt.Printf("size: %d\n", resp.ContentLength)

Works if web server sends back a Content-Length response header; not if the response is chunked instead.