将内容 URI 转换为 FileUpload

如何解决将内容 URI 转换为 FileUpload

我从 getContent 获取内容 URI，我想将其转换为 FileUpload

  object upload : FileUpload(mimetype) {
    override fun contentLength(): Long {
      Todo("return contentLength here")
    }
    override fun fileName(): String? {
      Todo("return fileName to use in the multipart request here")
    }
    override fun writeto(sink: BufferedSink) {
      Todo("write the data here")
    }
  }