golang 转换相对URL到绝对URL

func fixUrl(href, base string) (string) {
  uri, err := url.Parse(href)
  if err != nil {
    return ""
  }
  baseUrl, err := url.Parse(base)
  if err != nil {
    return ""
  }
  uri = baseUrl.ResolveReference(uri)
  return uri.String()
}