要识别用户在Visual Basic中更改Windows默认打印机的时间,您可以使用Windows API(应用程序编程接口)来监视注册表更改。以下是一个简单的示例,说明如何在Visual Basic中实现这一功能:
Microsoft Win32 API
中的RegNotifyChangeKeyValue
函数,该函数允许您监视注册表更改。Private Declare Function RegNotifyChangeKeyValue Lib "advapi32.dll" (ByVal hKey As Long, ByVal bWatchSubtree As Boolean, ByVal dwNotifyFilter As Long, ByVal hEvent As Long, ByVal fAsynchronous As Boolean) As Long
Function GetDefaultPrinter() As String
Dim objWMIService, objPrinter
Dim strPrinterName As String
Set objWMIService = GetObject("winmgmts:\\.\root\cimv2")
Set objPrinter = objWMIService.ExecQuery("Select * From Win32_Printer Where Default = True")
For Each printer In objPrinter
strPrinterName = printer.Name
Next
GetDefaultPrinter = strPrinterName
End Function
Sub MonitorRegistryChanges()
Dim hKey As Long
Dim strPrinterName As String
Dim strPreviousPrinterName As String
' 打开注册表键
hKey = OpenKey("HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows")
' 获取当前默认打印机名称
strPreviousPrinterName = GetDefaultPrinter()
' 循环监视注册表更改
Do
' 等待注册表更改事件
RegNotifyChangeKeyValue(hKey, True, &H1 Or &H2 Or &H4, 0, False)
' 获取新的默认打印机名称
strPrinterName = GetDefaultPrinter()
' 检查默认打印机是否已更改
If strPrinterName <> strPreviousPrinterName Then
MsgBox "默认打印机已更改:" & vbCrLf & _
"旧打印机:" & strPreviousPrinterName & vbCrLf & _
"新打印机:" & strPrinterName
strPreviousPrinterName = strPrinterName
End If
Loop
' 关闭注册表键
CloseKey(hKey)
End Sub
MonitorRegistryChanges
函数来监视默认打印机更改。Sub Main()
MonitorRegistryChanges
End Sub
这个示例将弹出一个消息框,显示默认打印机更改的时间和新旧打印机名称。请注意,这个示例仅适用于当前用户的注册表更改。如果您需要监视所有用户的更改,您需要以管理员身份运行程序并监视不同的注册表键。
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