Powershell FileSystemWatcher 脚本在一些新文件上触发两次

Question

我正在使用 FileSystemWatcher 来监控文档扫描到的文件夹。当检测到新文件时，它会发送电子邮件通知某人。它按原样工作，但有时(不是每个文件)它会在新文件上触发 2 或 3 次，并为同一文件发送电子邮件 2-3 次。我猜这与扫描仪或类似工具创建文件的方式有关。

我正在尝试找出一种方法来防止这种情况发生，以确保它只为每个文件发送一封电子邮件。任何建议将不胜感激。

$PathToMonitor = "\\path\to\folder"

$FileSystemWatcher = New-Object System.IO.FileSystemWatcher
$FileSystemWatcher.Path  = $PathToMonitor
$FileSystemWatcher.Filter  = "*.*"
$FileSystemWatcher.IncludeSubdirectories = $false

$FileSystemWatcher.EnableRaisingEvents = $true

$Action = {
    if ($EventArgs.Name -notlike "*.pdf" -and $EventArgs.Name -notlike "*.tif") {
        return
    }
        $details = $event.SourceEventArgs
        $Name = $details.Name
        $Timestamp = $event.TimeGenerated
        $text = "{0} was submitted on {1}." -f $Name, $Timestamp
        
        $FromAddress = "Email1 <email1@email.com>"
        $ToAddress = "Email2 <Email2@email.com>"
        $Subject = "New File"
        $SMTPserver = "123.4.5.678"
    
        Send-MailMessage -From $FromAddress -To $ToAddress -Subject $Subject -Body $text -SmtpServer $SMTPserver
    
}

$handlers = . {
    Register-ObjectEvent -InputObject $FileSystemWatcher -EventName Created -Action $Action -SourceIdentifier FSCreateConsumer
}

try {
    do {
        Wait-Event -Timeout 5
    } while ($true)
}
finally {
    Unregister-Event -SourceIdentifier FSCreateConsumer
    
    $handlers | Remove-Job
    
    $FileSystemWatcher.EnableRaisingEvents = $false
    $FileSystemWatcher.Dispose()
}

Answer 1

这可能是你听多了notifications .默认为 LastWrite、FileName 和 DirectoryNameFileName 足以满足您的需要，可能会阻止您的问题。

$FileSystemWatcher.NotifyFilter = [System.IO.NotifyFilters]::FileName

顺便说一下，我不知道你为什么要使用 Wait-Event -Timeout 5。脚本在没有 try{} block 的情况下工作正常。

编辑:添加一个 ConcurrentDictionary 以避免重复事件

试试这个示例代码。我只包含了您脚本的开头部分。结束未被触及。

$PathToMonitor = "\\path\to\folder"
$KeepFiles = 5  #minutes

$MonitoredFiles = New-Object -TypeName 'System.Collections.Concurrent.ConcurrentDictionary[[System.String],[System.DateTime]]'

$FileSystemWatcher = New-Object System.IO.FileSystemWatcher
$FileSystemWatcher.Path  = $PathToMonitor
$FileSystemWatcher.Filter  = "*.*"
$FileSystemWatcher.IncludeSubdirectories = $false
$FileSystemWatcher.NotifyFilter = [System.IO.NotifyFilters]::FileName

$FileSystemWatcher.EnableRaisingEvents = $true


$Action = {
    if ($EventArgs.Name -notlike "*.pdf" -and $EventArgs.Name -notlike "*.tif") {
        return
    }

    #Cleaning events -gt 5mn
    $Now = [System.DateTime]::Now
    $OriginEventDate = [System.DateTime]::MinValue
    foreach($MonitoredFile in [System.Linq.Enumerable]::ToList(($MonitoredFiles.Keys))) {
        if ($MonitoredFiles.TryGetValue($MonitoredFile, [ref]$OriginEventDate)) {
            if ($OriginEventDate.AddMinutes($KeepFiles) -gt $Now) {
                try {
                    [void]$MonitoredFiles.Remove($MonitoredFile)
                } 
                catch {}
            }
        }
    }

    $ProcessEvent = $false
    # any same file creation event within 5mn are discarded
    $OriginEventDate = [System.DateTime]::MinValue
    if ($MonitoredFiles.TryGetValue($event.SourceEventArgs.Name, [ref]$OriginEventDate)) {
        if ($OriginEventDate -ne [System.DateTime]::MinValue -and $OriginEventDate.AddMinutes($KeepFiles) -le $Now) {
            return
        }
        else {
            $ProcessEvent = $true
        }
    }
    else {
        #not successful means a concurrent event was successful, so discard this one.
        if ($MonitoredFiles.TryAdd($event.SourceEventArgs.Name, $event.SourceEventArgs.TimeGenerated)) {
            $ProcessEvent = $true
        }
        else {
            return
        }
    }

    
    if ($ProcessEvent) {
            
        $details = $event.SourceEventArgs
        $Name = $details.Name
        $Timestamp = $event.TimeGenerated
        $text = "{0} was submitted on {1}." -f $Name, $Timestamp
        
        $FromAddress = "Email1 <email1@email.com>"
        $ToAddress = "Email2 <Email2@email.com>"
        $Subject = "New File"
        $SMTPserver = "123.4.5.678"
    
        Send-MailMessage -From $FromAddress -To $ToAddress -Subject $Subject -Body $text -SmtpServer $SMTPserver
    }
}