/// <summary>
    ///
    /// </summary>
    /// <param name="args"></param>
    /// <returns></returns>
    protected override async Task OnFileChange(InputFileChangeEventArgs args)
    {
        CurrentFile = new UploadFile()
        {
            OriginFileName = args.File.Name,
            Size           = args.File.Size,
            File           = args.File,
            Uploaded       = false
        };
        CurrentFile.ValidateId = $"{Id}_{CurrentFile.GetHashCode()}";

        if (IsSingle)
        {
            // 单图片模式
            DefaultFileList?.Clear();
            UploadFiles.Clear();
        }

        UploadFiles.Add(CurrentFile);

        await base.OnFileChange(args);

        // ValidateFile 后 IsValid 才有值
        CurrentFile.IsValid = IsValid;

        if (OnChange != null)
        {
            await OnChange(CurrentFile);
        }
        else
        {
            await CurrentFile.RequestBase64ImageFileAsync(CurrentFile.File.ContentType, 320, 240);
        }
    }