有没有办法在PowerShell中使用WebClient对象监视下载的进度？

Question

我正在使用如下简单的行下载文件:

$webclient = New-Object -TypeName System.Net.WebClient
$webclient.DownloadFile("https://www.example.com/file", "C:/Local/Path/file")

问题是我想在下载时使用弹出窗口或使用shell中的进度条向用户显示消息.下载完成时是否可以使弹出框消失,或者监视下载进度的进度条是否可以？

Answer 1

要显示下载文件的进度条,请查看Jason Niver的博客文章:

在Power Shell中从Internet下载文件(带进度)

基本上,您可以创建一个仍然使用Web客户端功能的功能,但包括捕获状态的方法.然后,您可以使用Write-Progress Power shell功能向用户显示状态.

function DownloadFile($url, $targetFile)

{

   $uri = New-Object "System.Uri" "$url"

   $request = [System.Net.HttpWebRequest]::Create($uri)

   $request.set_Timeout(15000) #15 second timeout

   $response = $request.GetResponse()

   $totalLength = [System.Math]::Floor($response.get_ContentLength()/1024)

   $responseStream = $response.GetResponseStream()

   $targetStream = New-Object -TypeName System.IO.FileStream -ArgumentList $targetFile, Create

   $buffer = new-object byte[] 10KB

   $count = $responseStream.Read($buffer,0,$buffer.length)

   $downloadedBytes = $count

   while ($count -gt 0)

   {

       $targetStream.Write($buffer, 0, $count)

       $count = $responseStream.Read($buffer,0,$buffer.length)

       $downloadedBytes = $downloadedBytes + $count

       Write-Progress -activity "Downloading file '$($url.split('/') | Select -Last 1)'" -status "Downloaded ($([System.Math]::Floor($downloadedBytes/1024))K of $($totalLength)K): " -PercentComplete ((([System.Math]::Floor($downloadedBytes/1024)) / $totalLength)  * 100)

   }

   Write-Progress -activity "Finished downloading file '$($url.split('/') | Select -Last 1)'"

   $targetStream.Flush()

   $targetStream.Close()

   $targetStream.Dispose()

   $responseStream.Dispose()

}

然后你只需要调用该函数:

downloadFile "http://example.com/largefile.zip" "c:\temp\largefile.zip"

此外,还有一些其他Write-Progress示例.

写进展

Answer 2

在V2中你可以使用BitsTransfer模块,例如:

Import-Module BitsTransfer
Start-BitsTransfer https://www.example.com/file C:/Local/Path/file