异步FTP上传

Question

异步FTP上传

3

我该如何使下面的代码异步化，我不知道异步与FTP上传是如何工作的。我尝试了很多方式，但我不知道在上传文件时应将'await'放在哪里。

public static async void SelectRectangle(Point SourcePoint, Point DestinationPoint, Rectangle SelectionRectangle, string FilePath)
{
    using (Bitmap bitmap = new Bitmap(SelectionRectangle.Width, SelectionRectangle.Height))
    {
        using (Graphics g = Graphics.FromImage(bitmap))
        {

            g.CopyFromScreen(SourcePoint, DestinationPoint, SelectionRectangle.Size);

            FtpWebRequest request = (FtpWebRequest)FtpWebRequest.Create(Properties.Settings.Default.ftphost + Properties.Settings.Default.ftppath + FilePath + "." + Properties.Settings.Default.extension_plain);
            request.Method = WebRequestMethods.Ftp.UploadFile;
            request.Credentials = new NetworkCredential(Properties.Settings.Default.ftpuser, Properties.Settings.Default.ftppassword);
            request.UseBinary = true;

            bitmap.Save(request.GetRequestStream(), ImageFormat.Png);
        }
    }
}

Joery.

- Joery

2

除非调用方法被标记为async（并且因此，（async）调用堆栈一直是异步的），否则您不能使用async/await。 - spender

1个回答

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- Lee · Accepted Answer

你需要将这个方法变成 async，然后对于任何异步操作使用 await。目前只有一个异步操作，所以以下代码应该可以工作：

public static async Task SelectRectangle(Point SourcePoint, Point DestinationPoint, Rectangle SelectionRectangle, string FilePath)
{
    using (Bitmap bitmap = new Bitmap(SelectionRectangle.Width, SelectionRectangle.Height))
    {
        using (Graphics g = Graphics.FromImage(bitmap))
        {

            g.CopyFromScreen(SourcePoint, DestinationPoint, SelectionRectangle.Size);

            FtpWebRequest request = (FtpWebRequest)FtpWebRequest.Create(Properties.Settings.Default.ftphost + Properties.Settings.Default.ftppath + FilePath + "." + Properties.Settings.Default.extension_plain);
            request.Method = WebRequestMethods.Ftp.UploadFile;
            request.Credentials = new NetworkCredential(Properties.Settings.Default.ftpuser, Properties.Settings.Default.ftppassword);
            request.UseBinary = true;

            Stream rs = await request.GetRequestStreamAsync();
            bitmap.Save(rs, ImageFormat.Png);
        }
    }
}