正确清除打印机队列

Question

场景 - 创建一个能够在用户机器上添加和删除打印机的应用程序后，我遇到了一个关键错误：

1) 如果打印队列（System32\spool\PRINTERS）中存在打印作业，则不会删除打印机，这些是 SPL 和 SHD 文件

2) 如果有一个大小为 23,000kb 的文件，我需要一种方法来停止进程，直到命令完成

我当前的方法流程

                    Dim p As Process = New Process()
                    p.StartInfo.WindowStyle = ProcessWindowStyle.Hidden
                    p.StartInfo.FileName = "cmd.exe"

                    For i = 0 To 2
                        Select Case i
                            Case 0
                                'Stop spooler and dependencies
                                p.StartInfo.Arguments = "/c net stop spooler /yes"
                                p.Start()

                            Case 1
                                'Delete all queues within folder
                                p.StartInfo.Arguments = "/c del C:\Windows\System32\spool\PRINTERS\*.* /F /Q"
                                p.Start()

                                'Delete printer
                                printer.Delete()

                            Case 2
                                'Restart the spooler service
                                p.StartInfo.Arguments = "/c net start spooler"
                                p.Start()

                        End Select
                    Next                 

带线程：

    Dim p As Process = New Process()
                    p.StartInfo.WindowStyle = ProcessWindowStyle.Hidden
                    p.StartInfo.FileName = "cmd.exe"

                    For i = 0 To 2
                        Select Case i
                            Case 0
                                'Stop spooler and dependencies
                                p.StartInfo.Arguments = "/c net stop spooler /yes"
                                p.Start()
                                'Allow time for the application to purge larger file sizes
                                Threading.Thread.Sleep(2500)
                            Case 1
                                'Delete all queues within folder
                                p.StartInfo.Arguments = "/c del C:\Windows\System32\spool\PRINTERS\*.* /F /Q"
                                p.Start()

                                'Delete printer
                                printer.Delete()

                            Case 2
                                'Restart the spooler service
                                p.StartInfo.Arguments = "/c net start spooler"
                                p.Start()

                                Threading.Thread.Sleep(2500)
                        End Select
                    Next

这两种方法都不能正常工作，应用程序没有足够的时间让后台处理程序服务停止。这意味着文件不会被删除，导致删除打印机时出错。

我希望从这个帖子中获得什么：

我需要一些有关如何有效操作此程序的指导。非常感谢

Answer 1

您可以在您的代码中停止该服务：

Option Infer On
Option Strict On

Imports System.ServiceProcess
'........

Sub StopService(ByVal serviceName As String)

    Using sc = New ServiceController(serviceName)
        Dim ts = TimeSpan.FromSeconds(30)
        Try
            sc.Stop()
            sc.WaitForStatus(ServiceControllerStatus.Stopped, ts)
            log.AppendFormatLine("Stopped {0} service.", serviceName)
        Catch ex As InvalidOperationException
            log.AppendFormatLine("** Could not stop {0} service because {1}.", serviceName, ex.Message)
        Catch ex As TimeoutException
            log.AppendFormatLine("** Timeout after waiting {0} seconds for {1} service to stop.", ts.Seconds.ToString)
        End Try
    End Using

End Sub