powershell：异步 FileSystemWatcher 触发时更改 GUI 元素

Question

我喜欢在创建新文件时更改 GUI 元素（powershell ISE 中的 windows-form）。因此我设置了一个表单并在另一个运行空间（MWE）中启动了一个文件系统观察器：

# this function should be called when a new file is created
function foobar(){
    $form.BackColor = "black"
}

# set up runspace for async FileSystemWatcher
$Runspace = [runspacefactory]::CreateRunspace()
$PowerShell = [System.Management.Automation.PowerShell]::Create()
$PowerShell.runspace = $Runspace
$Runspace.Open()

[void]$PowerShell.AddScript({
    $logFile = 'C:\powershell\test.log'  
    $dirName = 'C:\powershell\'

    $hotFolder = New-Object IO.FileSystemWatcher $dirName -Property @{IncludeSubdirectories = $false;NotifyFilter = [IO.NotifyFilters]'FileName, LastWrite'}
    Register-ObjectEvent $hotFolder Created -SourceIdentifier FileCreated -Action {
          $name = $Event.SourceEventArgs.Name
          $path = $Event.SourceEventArgs.FullPath 
          $changeType = $Event.SourceEventArgs.ChangeType
          $timeStamp = $Event.TimeGenerated

          Out-File -FilePath $logFile -Append -InputObject "The file '$name' was $changeType at $timeStamp"

      # this call does not work
      foobar
      }  
})

$AsyncObject = $PowerShell.BeginInvoke()

# set up form
$form = New-Object System.Windows.Forms.Form
$form.ShowDialog()

FileSystemWatcher 工作（写入日志文件），但“foobar”的调用被忽略/不起作用。

我的第一次尝试是在表单中注册 FileSystemWatcher，但它不起作用（类似于：FileSystemWatcher and GUI）。我找到了这个线程FileSystemWatcher kommt nicht mit Form zurecht (german only)，它建议使用运行空间。

运行空间解决了卡住的 GUI 问题，但是当 fileSystemWatcher 注册一个新文件时，我需要一种方法来触发表单中的事件。我怎样才能做到这一点？

简而言之：

1) FileSystemWatcher 如何触发 GUI 元素的更改

2) 在这种情况下，运行空间是正确的方法

我不是 powershell 方面的专家（仍在学习）。感谢您提供任何帮助和建议。

提前致谢。

Answer 1

我做了一些研究并找到了解决方案：

• 添加了一个同步哈希表以在运行空间之间共享变量
• 在哈希表中添加了表单的按钮（该按钮将隐藏在最终版本的绘图中。Size(0,0)）
• fileSystemWatcher 使用 performclick() 点击按钮
• 按钮在点击时调用所需的功能

还有一点觉得别扭：

• 要取消注册 fileSystemWatcher，我将共享变量设置为 1 并通过生成文件来触发 fileSystemWatcher

有没有更优雅的方法来做到这一点？

我是否遗漏了一些代码过于复杂的地方？

感谢任何cmets。

这是一个 MWE。要使用它，请将 $dir 变量设置为您的需要。 （MWE 在 Win7 附带的未更新的 powershell 中不起作用）

# set working dir
$dir = 'C:\Downloads'
Write-Host 'working dir' $dir


# create function which is called when new file is created
function showPath($path){
  $label.Text = $path
}

# set up runspace for async FileSystemWatcher
$Runspace = [runspacefactory]::CreateRunspace()
$Runspace.Open()

# synchronized hashtable and hashtable elements
$sync = [Hashtable]::Synchronized(@{})
  $sync.path = 1  # random start value
  $sync.exit = 0  # switch: if set to 1 fileSystemWatcher will be unregistert when next event occurs
  $sync.dir = $dir

  $btnNewFile= New-Object System.Windows.Forms.Button
  $btnNewFile.Location = New-Object System.Drawing.Size(220,10)
  $btnNewFile.Size = New-Object System.Drawing.Size(150,23)
  $btnNewFile.Text = "do not click - fake button"
  $btnNewFile.Add_Click({
    $newPath = $sync.path
    $form.text = $newPath
    showPath($newPath)
  })

  $sync.btnNewFile = $btnNewFile

$Runspace.SessionStateProxy.SetVariable("sync", $sync)

$PowerShell = [System.Management.Automation.PowerShell]::Create()
$PowerShell.runspace = $Runspace

[void]$PowerShell.AddScript({
    $logFile = Join-Path $sync.dir test.log  
    $dirName = $sync.dir

    $hotFolder = New-Object IO.FileSystemWatcher $dirName -Property @{IncludeSubdirectories = $false;NotifyFilter = [IO.NotifyFilters]'FileName, LastWrite'}
    Register-ObjectEvent $hotFolder Created -SourceIdentifier FileCreated -Action {
          $path = $Event.SourceEventArgs.FullPath 
          $name = $Event.SourceEventArgs.Name
          $changeType = $Event.SourceEventArgs.ChangeType
          $timeStamp = $Event.TimeGenerated

          # check if exit condition is met
          if($sync.exit -eq 1){
            Out-File -FilePath $logFile -Append -InputObject "Exit file: '$name'"
            Unregister-Event FileCreated
          }
          else{
          Out-File -FilePath $logFile -Append -InputObject "The file '$name' was $changeType at $timeStamp"

          # set path to synchroniszed variable
          $sync.path = $path

          # click Button to trigger function call
          $sync.btnNewFile.PerformClick() 
          }

      }
})

$AsyncObject = $PowerShell.BeginInvoke()

# GUI setup
$labelHeader = New-Object System.Windows.Forms.Label
$labelHeader.Location = New-Object System.Drawing.Size(10,50)
$labelHeader.Size = New-Object System.Drawing.Size(100,23)
$labelHeader.Text = 'path to new file:'

$label = New-Object System.Windows.Forms.Label
$label.Location = New-Object System.Drawing.Size(110,50)
$label.Size = New-Object System.Drawing.Size(200,23)
$label.Text = 'no file created'


$global:fileCounter = 0
$btnCreateFile = New-Object System.Windows.Forms.Button
$btnCreateFile.Location = New-Object System.Drawing.Size(10,10)
$btnCreateFile.Size = New-Object System.Drawing.Size(100,23)
$btnCreateFile.Text = "New File"
$btnCreateFile.Add_Click({
  $global:fileCounter+=1
  $fileName = "$global:fileCounter.txt"
  $newFile = Join-Path $dir $fileName
  New-Item $newFile -ItemType file
})

$btnExit = New-Object System.Windows.Forms.Button
$btnExit.Location = New-Object System.Drawing.Size(110,10)
$btnExit.Size = New-Object System.Drawing.Size(100,23)
$btnExit.Text = "&Exit"
$btnExit.Add_Click({
  $sync.Exit = 1
  $btnCreateFile.PerformClick() 
  $Powershell.Dispose()
  $form.Close()
})

# set up form
$form = New-Object System.Windows.Forms.Form
$form.Width = 400
$form.Height = 120
$form.Controls.Add($btnCreateFile)
$form.Controls.Add($btnExit)
$form.Controls.Add($labelHeader)
$form.Controls.Add($label)
$form.Controls.Add($sync.btnNewFile)

$form.ShowDialog()

Answer 2

我真的很喜欢你的解决方案，但正如你所说，这个问题不适用于 PS2.0，包括我需要的 Win7 服务包 1。

我的 GUI 更新解决方案适用于 PS2(win7) 和 PS3(win10)，它基于 Windows Presentation Framework(WPF) 而不是 Windows 窗体，因为有了 WPF，我们可以使用 Data Binding 和 @987654322 @ 界面。我的工作基于 Trevor Jones 网络 How-To，并提供了一些工作技巧。

关于取消注册系统的问题，我已从 VB 翻译为 PS，Mike Ober 在SpiceWorks 的帖子中，他基于全局变量和可能的错误注册和取消注册系统的概念启发了我。

这是我的代码：

Add-Type -AssemblyName PresentationFramework,PresentationCore,WindowsBase

Function Create-WPFWindow {
    Param($Hash)
    # Create a window object
    $Window = New-Object System.Windows.Window
    $Window.Width = '600'
    $Window.Height = '300'
    $Window.Title = 'WPF-CONTROL'
    $window.WindowStartupLocation = [System.Windows.WindowStartupLocation]::CenterScreen
    $Window.ResizeMode = [System.Windows.ResizeMode]::NoResize

    # Create a Label object
    $Label = New-Object System.Windows.Controls.Label
    $Label.Height = 40
    $Label.HorizontalContentAlignment = 'Left'
    $Label.VerticalContentAlignment = 'Center'
    $Label.FontSize = 15
    $Label.Content = 'Actividad:'
    $Hash.Label = $Label

    # Create a TextBlock object
    $TextBlock = New-Object System.Windows.Controls.TextBlock
    $TextBlock.Height = 150
    $TextBlock.FontSize = 20
    $TextBlock.TextWrapping = 'Wrap'
    $Hash.TextBlock = $TextBlock

    # Create a Button1 object
    $Button1 = New-Object System.Windows.Controls.Button
    $Button1.Width = 300
    $Button1.Height = 35
    $Button1.HorizontalContentAlignment = 'Center'
    $Button1.VerticalContentAlignment = 'Center'
    $Button1.FontSize = 20
    $Button1.Content = 'Iniciar'
    $Hash.Button1 = $Button1

    # Assemble the window
    $StackPanel1 = New-Object System.Windows.Controls.StackPanel
    $StackPanel1.Margin = '150,20,5,5'
    $StackPanel1.Orientation = 'Horizontal'
    $StackPanel1.Children.Add($Button1)
    $StackPanel2 = New-Object System.Windows.Controls.StackPanel
    $StackPanel2.Margin = '5,5,5,5'
    $StackPanel2.Orientation = 'Vertical'
    $StackPanel2.Children.Add($Label)
    $StackPanel2.Children.Add($TextBlock)
    $StackPanel = New-Object System.Windows.Controls.StackPanel
    $StackPanel.Margin = '5,5,5,5'
    $StackPanel.Children.Add($StackPanel1)
    $StackPanel.Children.Add($StackPanel2)
    $Window.Content =  $StackPanel

    # Stop the service and release the resources
    $Window.Add_Closing({
        $Hash.On = $false
        $global:p.BeginInvoke()
        $global:p.Dispose()})
    $Hash.Window = $Window
}

$Hash = [hashtable]::Synchronized(@{})
# Create a WPF window and add it to a Hash table
Create-WPFWindow $Hash | Out-Null

# Create a datacontext for the TextBlock, we add it to the synchronized $Hash to update the GUI from the FileSystemWatcher Event.
$DataContext = New-Object System.Collections.ObjectModel.ObservableCollection[Object]
$Text = [string]'Pulse el botón para iniciar el sistema.'
$DataContext.Add($Text)
$Hash.TextBlock.DataContext = $DataContext
$Hash.DataContext = $DataContext
$Hash.path='C:\POWERSHELL_PROJECT\Result'
# These two vars are for my needs, you can obviate them or delete
$Hash.urlLOGIN=''
$Hash.urlLOTE=''
$Hash.fileWatcher = $null
$Hash.LOG='C:\POWERSHELL_PROJECT\Result\LOG.log'
$Hash.firstEvent = $false
$Hash.On=$false
$Hash.msg=''

# Create and set a binding on the TextBlock object
$Binding = New-Object System.Windows.Data.Binding -ArgumentList '[0]'
$Binding.Mode = [System.Windows.Data.BindingMode]::OneWay
[void][System.Windows.Data.BindingOperations]::SetBinding($Hash.TextBlock,[System.Windows.Controls.TextBlock]::TextProperty, $Binding)
# Add an event for the Button1 click to Register FileSystemWatcher and Unregister it
$Hash.Button1.Add_Click({
    if ($Hash.On -eq $true){ 
        $Hash.On = $false
        $Hash.Button1.Background = 'Green'
        $Hash.Button1.Content = 'Iniciar'
    }else{ 
        $Hash.On = $true
        $Hash.Button1.Background = 'Red'
        $Hash.Button1.Content = 'Detener'
    }
    $p.BeginInvoke() | Out-Null
})

# Multithreading runspaces for FileSystemWatcher
$rs_dForm = [Management.Automation.Runspaces.RunspaceFactory]::CreateRunspace()
$rs_dForm.ApartmentState = 'STA'
$rs_dForm.ThreadOptions = 'ReuseThread'
$rs_dForm.Open()
$rs_dForm.SessionStateProxy.SetVariable('Hash', $Hash)

$p = [PowerShell]::Create().AddScript({
        Function global:OnFileSystemWatcherError {
            FileEventListener -Path $Hash.path
        }
        # With simple function we can refresh the Textbox and Log
        Function global:Refresh-WPF-and-LOG {
            $Hash.DataContext[0] = $Hash.msg
            echo $Hash.msg >> $Hash.LOG
        }
        Function global:FileEventListener ($Path){
            if ($Hash.On){
                $Hash.fileWatcher = New-Object System.IO.FileSystemWatcher
                $Hash.fileWatcher.Path = $Path
                $Hash.fileWatcher.Filter = '*.xml'
                $Hash.fileWatcher.IncludeSubdirectories = $false
                $Hash.fileWatcher.InternalBufferSize = 32768
                $Hash.fileWatcher.EnableRaisingEvents=$true
                Register-ObjectEvent -InputObject $Hash.fileWatcher -EventName Changed -SourceIdentifier File.Changed -Action {
                    $Global:t = $event
                    if (!$Hash.firstEvent){
                        try{
                            # For example you can:
                            $Hash.msg = '[' + $(Get-Date -Format u | foreach {$_ -replace ' ','-'}).ToString() + ']--' + $event.SourceEventArgs.Name
                        }catch{
                            $Hash.msg = '[' + $(Get-Date -Format u | foreach {$_ -replace ' ','-'}).ToString() + ']--' + $_.Exception.Message + ' ' + $_.Exception.ItemName
                        }finally{
                            Refresh-WPF-and-LOG
                        }
                        $Hash.firstEvent=$true
                    }else{
                        $Hash.firstEvent=$false
                    }
                }
                # With this Register we control the errors from the FileSystemWatcher system, and reinit it this case
                Register-ObjectEvent -InputObject $Hash.fileWatcher -EventName Error -SourceIdentifier File.Error -Action {
                    $Global:t = $event
                    $Hash.On = $false
                    OnFileSystemWatcherError
                }
                $Hash.msg = '[' + $(Get-Date -Format u | foreach {$_ -replace ' ','-'}).ToString() + ']--' + 'Servicio INICIADO.'
            }else{
                if ( $Hash.fileWatcher -ne $null ){
                    $Hash.fileWatcher.EnableRaisingEvents=$false
                    Unregister-Event File.Changed
                    Unregister-Event File.Error
                    $Hash.fileWatcher.Dispose()
                    $Hash.fileWatcher=$null
                    $Hash.msg='[' + $(Get-Date -Format u | foreach {$_ -replace ' ','-'}).ToString() + ']--' + 'Sistema DETENIDO.'
                }
            }
            Refresh-WPF-and-LOG
        }
        FileEventListener -Path $Hash.path
})

$p.Runspace = $rs_dForm
# Show the window
$Hash.Window.ShowDialog() | Out-Null

希望能帮到你。