使用 System.IO.FileSystemWatcher 后使用 Powershell 循环文件

Question

在监视文件夹以创建扩展名为 .csv 的新文件的 PowerShell 脚本方面需要一些帮助。
当检测到新文件的创建时，会发生以下操作……

1. 文件的详细信息发送到日志文件
2. 文件的副本被发送到另一个名为“1_ToBeProcessed\MyImport.csv”的文件夹（注意文件已重命名为 MyImport.csv）
3. 文件已移至目录“\MYSERVER\MYCOMPANY\MYFOLDER\MyHistory”（使用其原始文件名）
4. 调用一个表达式来运行一个 .bat 文件，该文件将获取位于“\MYSERVER\MYCOMPANY\MYFOLDER\1_ToBeProcessed”中的文件并将该文件导入应用程序。
5. 然后该脚本会休眠 60 秒以允许导入完成，然后再处理下一个文件。 除非在脚本运行时创建另一个文件，否则此脚本一切正常。
   同一类型的多个文件可能会同时命中监视文件夹。因此，脚本可能会遍历五个文件，然后另一个文件可能会进入目录。发生这种情况时，脚本似乎会重新开始并开始循环遍历文件……但它会一遍又一遍地循环相同的文件。 我希望有人能指出我在这个脚本中做错了什么。由于添加了新文件，我如何让它在重新开始之前完成当前循环中正在处理的文件？ 我们将不胜感激任何可以提供的帮助！

这是我目前拥有的......

#Define watcher; Set path to watch; Set filter on file type
$filewatcher = New-Object System.IO.FileSystemWatcher
$filewatcher.Path = "\\MYSERVER\MYCOMPANY\MYFOLDER"
$filewatcher.Filter = "*.csv"                     

#Define "move to" and "copy to" paths
$moveTo = "\\MYSERVER\MYCOMPANY\MYFOLDER\MyHistory"
$copyTo = "\\MYSERVER\MYCOMPANY\MYFOLDER\1_ToBeProcessed\MyImport.csv"


#Define actions after an Event is Detected
$action = {$files = Get-ChildItem -Path $filewatcher.Path -Filter filewatcher.Filter 
        foreach ($file in $files)
        {
        #Define variables for log file
        $changeType = $Event.SourceEventArgs.ChangeType
        $logline = "$(Get-Date), $changeType, $file"
        #Actions to take
        Add-Content "\\MYSERVER\MYCOMPANY\MYFOLDER\3_Log\MyImportLog.txt" -value $logline
        Copy-Item $file.FullName -Destination $copyTo
        Move-Item $file.FullName -Destination $moveTo -Force
        Invoke-Expression "& '\\MYSERVER\MYCOMPANY\MYFOLDER\4_Scripts\PSscriptToRunBATfile.ps1'"
        #Pause the script for 60 seconds to allow it to finish posting the import before going to the next record
        Start-Sleep -Seconds 60
        }
        }

#Decide which events should be watched and set check frequency 
$onCreated = Register-ObjectEvent -InputObject $filewatcher -EventName "Created" -SourceIdentifier FileCreated -Action $action

Answer 1

我建议不要循环，而是在创建/更改文件时对其进行处理。也许如果你有很多文件要开始，你要么：

(a) 首先循环（并且只循环一次）。然后启用文件观察器来处理之后哪些文件发生了变化。

(b) 使用 FileChanged 和 FileCreated 启用文件观察器，然后“触摸”所有文件以触发您的代码。

# based on the script by By BigTeddy 05 September 2011
# simplified by Andy Myatt, to use one script block
# https://gallery.technet.microsoft.com/scriptcenter/Powershell-FileSystemWatche-dfd7084b

param(
    [string]$folderToWatch = "D:\Temp"
  , [string]$filter        = "*.*"
  , [string]$logFile       = "D:\Temp\Temp2\filewatcher.log"
)

# In the following line, you can change 'IncludeSubdirectories to $true if required.
$fsw = New-Object IO.FileSystemWatcher $folderToWatch, $filter -Property @{IncludeSubdirectories = $false;NotifyFilter = [IO.NotifyFilters]'FileName, LastWrite'}

# This script block is used/called by all 3 events and:
# appends the event to a log file, as well as reporting the event back to the console
$scriptBlock = {

  # REPLACE THIS SECTION WITH YOUR PROCESSING CODE
  $logFile = $event.MessageData # message data is how we pass in an argument to the event script block
  $name = $Event.SourceEventArgs.Name
  $changeType = $Event.SourceEventArgs.ChangeType
  $timeStamp = $Event.TimeGenerated
  Write-Host "$timeStamp|$changeType|'$name'" -fore green
  Out-File -FilePath $logFile -Append -InputObject "$timeStamp|$changeType|'$name'"
  # REPLACE THIS SECTION WITH YOUR PROCESSING CODE

}

# Here, all three events are registered.  You need only subscribe to events that you need:
Register-ObjectEvent $fsw Created -SourceIdentifier FileCreated -MessageData $logFile -Action $scriptBlock
Register-ObjectEvent $fsw Deleted -SourceIdentifier FileDeleted -MessageData $logFile -Action $scriptBlock
Register-ObjectEvent $fsw Changed -SourceIdentifier FileChanged -MessageData $logFile -Action $scriptBlock

# To stop the monitoring, run the following commands:
#  Unregister-Event FileDeleted  ;  Unregister-Event FileCreated  ;  Unregister-Event FileChanged


#This script uses the .NET FileSystemWatcher class to monitor file events in folder(s).
#The advantage of this method over using WMI eventing is that this can monitor sub-folders.
#The -Action parameter can contain any valid Powershell commands.
#The script can be set to a wildcard filter, and IncludeSubdirectories can be changed to $true.
#You need not subscribe to all three types of event.  All three are shown for example.

Answer 2

我认为您可能遇到了某种文件锁定问题，但如果不知道您的 PSscriptToRunBATfile.ps1 文件中的内容，就很难判断。

您的 filewatcher 在默认的 NotifyEvents 或 LastWrite | FileName | DirectoryName 上触发，然后您循环该目录。但是，您的 get-childitem 命令不一定会按照它们被复制的顺序返回文件。

更好的解决方案是让您根据您的 $Event 对象执行工作并更改您的 PS1 文件，将导致事件的文件作为输入参数：

$action = {$file = $Event.SourceEventArgs.FullPath
  #Define variables for log file
  $changeType = $Event.SourceEventArgs.ChangeType
  $logline = "$(Get-Date), $changeType, $file"
  #Actions to take
  Add-Content "\\MYSERVER\MYCOMPANY\MYFOLDER\3_Log\MyImportLog.txt" -value $logline
  Copy-Item $file -Destination $copyTo
  Move-Item $file -Destination $moveTo -Force
  Invoke-Expression "& '\\MYSERVER\MYCOMPANY\MYFOLDER\4_Scripts\PSscriptToRunBATfile.ps1' -InputFile $file"
}

注意：您可能希望将InternalBufferSize 增加到默认的 8k 以上，以免错过任何更改：

    $filewatcher.InternalBufferSize = 32kb