C# Amazon S3 上传带有进度条的文件

Question

I have one class function for upload a file to S3:

    public void UploadFile(string filePath, UploadProgress uploadProgress)
    {
        TransferUtilityUploadRequest uploadRequest;
        TransferUtility fileTransferUtility;

        try
        {
            mClient = new AmazonS3Client(Amazon.RegionEndpoint.EUWest1);

            uploadRequest =
                new TransferUtilityUploadRequest
                {
                    BucketName = BUCKETNAME,
                    FilePath = filePath
                };

            uploadRequest.UploadProgressEvent += new EventHandler<UploadProgressArgs>(uploadProgress);

            fileTransferUtility = new TransferUtility(mClient);
            fileTransferUtility.Upload(uploadRequest);
        }
        catch (AmazonS3Exception s3Exception)
        {
            throw s3Exception;
        }
    }

From the form class, I have a function for update the progressbar:

    private void UploadFile_ProgressBar(object sender, UploadProgressArgs e)
    {
        int pctProgress = (int)(e.TransferredBytes * 100 / e.TotalBytes);
        progressBarUpload.Value = pctProgress;
        progressBarUpload.Invalidate();

        Console.WriteLine(e.TransferredBytes + " / " + e.TotalBytes + Environment.NewLine);            
    }

And the call to upload file is:

    mS3.UploadFile(fileToUpload, UploadFile_ProgressBar);

The console show the progress but the progressbar no works. What am I doing wrong?

Thanks in advance!

Answer 1

I believe you are creating a Windows Form application with your progressbar. So, check this out: http://www.dotnetperls.com/progressbar

Also, I saw you are using the .Invalidate Method of Progressbar. As documentation says, this method does force a synchronous paint, without the Update method. Try it out.

Calling the Invalidate method does not force a synchronous paint; to force a synchronous paint, call the Update method after calling the Invalidate method. When this method is called with no parameters, the entire client area is added to the update region.

https://msdn.microsoft.com/en-us/library/598t492a(v=vs.100).aspx

Cheers!

Answer 2

The Problem is That You Can not access member of System.Windows.Forms.Control from different thread than UI thread will cause cross-thread exception. There is only one thread (UI thread), that is allowed to access System.Windows.Forms.Control and its subclasses members.

To Solve This You have to use the Invoke Method like this:

this.BeginInvoke(new Action(() =>
{
    this.progressBarUpload.Value = pctProgress;
}));