使用进度条时，event.TotalBytes 总是为 0

[feiquan666]

使用进度条时，event.TotalBytes 总是为 0
源代码如下

func SaveFiles(folderId uint, files []*multipart.FileHeader) (bool, *global.MyError) {
	key := "***************************"
	secret := "****************************"
	bucketName := "*********************"
	endpoint := "************"
	client, err := oss.New(endpoint, key, secret)
	if err != nil {
		log.Printf("建立连接失败：%v", err)
	}
	bucket, err := client.Bucket(bucketName)
	if err != nil {
		log.Printf("获取 Bucket 失败：%v", err)
	}
	f, err := files[0].Open()
	if err != nil {
		log.Printf("files[0].Open() 失败：%v", err)
	}
	reader := bufio.NewReader(f)
	fmt.Println(reader.Size())
	err = bucket.PutObject("Test/"+files[0].Filename, reader, oss.Progress(&OssProgressListener{}))
	if err != nil {
		log.Printf("PutObject 失败：%v", err)
	}
	return false, nil
}

type OssProgressListener struct {
}

// 定义进度变更事件处理函数。
func (listener *OssProgressListener) ProgressChanged(event *oss.ProgressEvent) {
	totalBytes := event.TotalBytes
	switch event.EventType {
	case oss.TransferStartedEvent:
		fmt.Printf("Transfer Started, ConsumedBytes: %d, TotalBytes %d.\n",
			event.ConsumedBytes, totalBytes)
	case oss.TransferDataEvent:
		rate := 0
		if totalBytes != 0 {
			rate = int(event.ConsumedBytes * 100 / totalBytes)
		}
		fmt.Printf("\rTransfer Data, ConsumedBytes: %d, TotalBytes %d, %d%%.",
			event.ConsumedBytes, totalBytes, rate)
	case oss.TransferCompletedEvent:
		fmt.Printf("\nTransfer Completed, ConsumedBytes: %d, TotalBytes %d.\n",
			event.ConsumedBytes, totalBytes)
	case oss.TransferFailedEvent:
		fmt.Printf("\nTransfer Failed, ConsumedBytes: %d, TotalBytes %d.\n",
			event.ConsumedBytes, totalBytes)
	default:
	}
}