c# - 上传图片时 PC 卡住一秒

Question

我正在制作截取屏幕截图并通过 FTP 将该图像上传到 Web 主机的程序。我有问题，当程序上传图片时，PC 会卡住一秒，我想那一秒是图片上传的时间。用户一定不会觉得有什么东西在减慢他的 PC。

如何消除那一秒钟的卡住？

注意:这不是某种类型的病毒

/* Upload File */
public void upload(string remoteFile, string localFile)
{
    try
    {
        /* Create an FTP Request */
        ftpRequest = (FtpWebRequest)FtpWebRequest.Create(host + "/" + remoteFile);
        /* Log in to the FTP Server with the User Name and Password Provided */
        ftpRequest.Credentials = new NetworkCredential(user, pass);
        /* When in doubt, use these options */
        ftpRequest.UseBinary = true;
        ftpRequest.UsePassive = true;
        ftpRequest.KeepAlive = true;
        /* Specify the Type of FTP Request */
        ftpRequest.Method = WebRequestMethods.Ftp.UploadFile;
        /* Establish Return Communication with the FTP Server */
        ftpStream = ftpRequest.GetRequestStream();
        /* Open a File Stream to Read the File for Upload */
        FileStream localFileStream = new FileStream(localFile, FileMode.Open);
        /* Buffer for the Downloaded Data */
        byte[] byteBuffer = new byte[bufferSize];
        int bytesSent = localFileStream.Read(byteBuffer, 0, bufferSize);
        /* Upload the File by Sending the Buffered Data Until the Transfer is Complete */
        try
        {
            while (bytesSent != 0)
            {
                ftpStream.Write(byteBuffer, 0, bytesSent);
                bytesSent = localFileStream.Read(byteBuffer, 0, bufferSize);
            }
        }
        catch (Exception ex) { MessageBox.Show(ex.ToString()); }
        /* Resource Cleanup */
        localFileStream.Close();
        ftpStream.Close();
        ftpRequest = null;  
    }
    catch (Exception ex) { MessageBox.Show(ex.ToString()); }
    return;
}

这是我的上传功能

Answer 1

更改方法声明:

public async Task upload(string remoteFile, string localFile)

然后将调用更改为 Write:

await ftpStream.WriteAsync(byteBuffer, 0, bytesSent);

该方法中的其余 I/O 可能足够快，不需要切换到异步/等待方法。但您也可以考虑将它们切换过来。

请注意，您还必须更改 upload() 的调用站点。您需要将异步/等待模式“冒泡”到初始 UI 事件处理程序，它可以是 async void 而不是 async Task(所以您可以匹配所需的事件处理程序方法签名)。